Back to my fuel vapor in the lines.

[55 Tony]

OK, I don't know who wrote it but it finally sunk into my big fat head about using the mechanical pump is creating a low pressure in the fuel line, so it will boil easier. So I'm ready to go electric back as close the the tank as possible. Is a pump like this OK? https://www.summitracing.com/parts/crt-p4594
Will a pump like that run constantly? At one time many years back I had an electric pump but it sounded like a little jack hammer, and it only hammered when the pressure went down. I sure don't want one like that because I could hear it with open headers!!! The one thing that bothers me is the 1/4"NTP fitting that goes to a 3/8" hose. Why a 1/4"? I just had the 55 out today and it's warm for winter but was under 60° and my fuel pressure dropped before I hit 3rd, but it wasn't bad enough to make it stumble, well also because I left off the throttle. I'm sure a new tank with an in tank pump would be the best, but I'm sure hoping I don't have to go that far.

I also have heard more than 1 person say they ran an electric through the mechanical just in case the electric failed. I suppose because mechanical pumps tend to give a warning and die more slowly than an electric. Anyone running there's like that? As much as I'd like that kind of backup, I also would be concerned about it helping to raise the fuel temperature. It does have a 1/8" spacer for heat insulation from the block, but with the hot air from the radiator the mechanical pump gets pretty hot.

So to sum up, I was w, wr, wrrr, wrrroo, wwwwrrrooo, ah, not correct.

[55 Rescue Dog]

There must be something else going on not caused by using mechanical fuel pump, which work great. Some pictures of your setup would be a great help to diagnose your fuel pressure issue.

[Rick_L]

A 50 gph electric pump won't support much power.

An electric pump needs a proper installation, most importantly gravity feed or in-tank installation.

A good mechanical pump with a proper installation will support 550 rwhp, or about 650 hp at the flywheel. Are you there?

If you're having problems, look for an air leak, a pickup problem, or a bad regulator. You should have a 3/8" line from the pickup to the pump.

[55 Tony]

Pictures, yes I keep forgetting about pictures. I'll work on that.

Electric pump, gravity feed ... my tank has a drain plug! Actually I thought of that last week but I forgot it again until now. At least if I had a leak I could see it!

650 at the flywheel? I highly doubt that. The person who held my hand when I was buying parts guesstimated at either 450 or 475HP, I forget which. Since that time for various reasons I've doubted the original calculated 10:1 static compression, I believe it's higher. Cranking compression averages 210psi. The big unknown factor is because I didn't CC the heads. Still ... 650HP? I don't think so. Any idea what it takes for a 12.5 second 1/4 mile with poor traction street tires on a poor traction street. Oh and with 3.42 gears?

Also, this "running out of fuel" problem has been with me before the motor was redone, when it for sure had a lot less HP, a LOT. At first I was running the original line, then replaced it and the pickup with 3/8". It's been through two fuel pumps and two regulators.

The one common denominator throughout years of this has been HEAT. A warm day with winter gas, or a hot day with summer gas. Get up to 75° on winter gas and forget it. Right now I have a fuel pressure gauge taped on the outside of the windshield. I had never known till recently just how often the pressure goes down but is still enough to keep it running.

Recently I learned about 99% of gasoline in CA, and some in a few major cities with smog problems, they have laws that really increase the boiling point (REID vapor pressure) of gasoline. That's one good thing about their rules concerning pollution, good gas!

I'm really thinking going from the drain hole to an electric pump. Just need to be sure to get a pump that is up to the task.

[chevynut]

GO back and read your prior thread on this. ;)

[55 Tony]

GO back and read your prior thread on this. ;)

I did but I didn't find any pertinent info except I did put the fuel gauge on the windshield and it's fed from a point close to the carb.
Although I could have missed something.

[markm]

eBay item number:

282735511172

Like I said last time one of these plumbed with 1/2 line, with a HP mech pump feeds two Holleys. .Probably overkill but it works and looks cool.

[55 Tony]

I have problems with a full tank, so a sump isn't going to help. If I was getting serious about racing yes maybe. But yes, it does look cool!

[markm]

The idea of rear sump is on hard acceleration when fuel is sloshed back in tank it is forced forward. I will let the Jegs book explain.















Universal Style Fuel Sump Tanks

The issue with many factory fuel tanks is they weren't designed to supply the fuel required by high-horsepower motors under hard acceleration. Most factory gas tank pickups are located in the front of the tank, which allows the fuel pump to ingest air during acceleration and thus briefly lose fuel pressure. Eliminate the problem by installing a Competition Engineering Fuel Tank Sump in the lowest portion of the rear of the fuel tank. This guarantees your engine will receive consistent fuel pressure under even the hardest acceleration

[55 Rescue Dog]

There are countless oval track race cars out there running 600+HP, 7500+RPM engines, running a mandatory mechanical fuel pump in 90+ degree weather.

[55 Tony]

There are countless oval track race cars out there running 600+HP, 7500+RPM engines, running a mandatory mechanical fuel pump in 90+ degree weather.
Are they running the same pump gas with the same Reid vapor pressure as I get here?
http://www.jmcampbell.com/tip-of-the-month/2016/02/correlations-for-conversion-between-true-and-reid-vapor-pressures-tvp-and-rvp/

[55 Rescue Dog]

Are they running the same pump gas with the same Reid vapor pressure as I get here?
http://www.jmcampbell.com/tip-of-the-month/2016/02/correlations-for-conversion-between-true-and-reid-vapor-pressures-tvp-and-rvp/
I have no idea, but maybe get some good race gas and see if that makes a difference, or set it up for E85 and make even more power. I'm running 50% 110 octane gas with 87 unleaded and it works great. What do the race cars in your area run for fuel?

[markm]

Even my SBC powered drag Camaro uses a mech pump, However I do run a 400 gph electric on my BBC drag Camaro. It has a fuel cell in trunk and the pump is mounted below it with #10 an hose going forward. Not a very street friendly setup Electric pumps are pushers not pullers. This is why late model FI cars have pump in tank. .

[55 Tony]

RescueD, I don't know where to find racing gas around here or anywhere. I guess I'd have to find a race track.
Just so you got it straight, octane has nothing at all to do with the boiling point or reid vapor pressure of gasoline.
Reid vapor pressure and fuel temperature (and the pressure or slight vacuum in fuel lines (before and after the pump)) have everything to do with the vapor point of gasoline and vapor lock. If I'm running pump gas and the pump is sucking hard enough to create a 1psi vacuum, that is a huge difference in the vapor pressure from the same fuel at 0 psi. It will vaporize at a lower temperature. You know how a sealed container of gas left to sit a while when opened will release fumes under pressure. The same thing happens in fuel lines. The most volatile ingredient in gas is usually butane and that will boil at a much lower temperature then most of the other ingredients. Just try to use a butane lighter below 32F. That is below its boiling point so it has no pressure to push vapor out to burn. Warm it in your hands or pocket and it literally boils inside the lighter and then vapor under pressure comes out to be ignited with a spark. Unfortunately an engine will not run on vapor. It needs atomized liquid. But they put butane in our gasoline. I hope that makes sense and is more or less correct.

[55 Tony]

Even my SBC powered drag Camaro uses a mech pump, However I do run a 400 gph electric on my BBC drag Camaro. It has a fuel cell in trunk and the pump is mounted below it with #10 an hose going forward. Not a very street friendly setup Electric pumps are pushers not pullers. This is why late model FI cars have pump in tank. .

And what is the Reid vapor pressure of the gasoline you run? Are you running pump gas?

[markm]

I recently attended a Renegade race fuel seminar, they have a new Hotrod 93 fuel with zero alcohol I can buy it for 4.95 a gallon at the pump locally. My race cars live on their 110. if they ever have a program in your area I would encourage anyone to attend.
https://www.renegaderacefuel.com/

[55 Tony]

I recently attended a Renegade race fuel seminar, they have a new Hotrod 93 fuel with zero alcohol I can buy it for 4.95 a gallon at the pump locally. My race cars live on their 110. if they ever have a program in your area I would encourage anyone to attend.
https://www.renegaderacefuel.com/

That seminar sound interesting. Maybe I can call them and ask what their Reid vapor pressure value is. Do you know what it is for their 110?

Edit: I just emailed them asking about the vapor pressure.

[chasracer]

I am stepping in here and not fully aware of your parts and combo - so bear with me please.

I think the perfect combination for a slightly warmed up street combination is a stock type fuel pump that is of hi-performance nature - I have used the Holley brand in the past but I have no idea of whether those are good now or not - things change. I am sure there are others out there that provide plenty of pressure and volume. To lessen the demands on the pulling side of the pump, I have used the small 12v electric pumps that you can find at almost any automotive parts shop or online. These only provide about 4-4.5 pounds of pressure but they are quiet and are very good at keeping fuel at the stock type pump. If pump noise is an issue, consider mounting the pump to the frame with a thick piece of rubber as an insulator. The sidewall of an old tire is a good source for the rubber piece. (BTW - this rubber also works nicely for a stock body mount isolator) Another issue that I see on a LOT of cars intended for mostly street use is the killer fuel line size. I understand that there are plenty of people running 1/2" or larger fuel lines without any problems but the original Hemi powered Chrysler cars with dual 4 barrel carbs only had a 3/8" feed line and that was considered "big" back then. The larger that line gets, the harder it is to push fuel through it and unless you are supporting 600+ horsepower that needs that kind of fuel volume it can be another item that is causing issues. The type of fuel that we can purchase at the pumps today is completely different from what we purchased in the mid-70's. To make up for the lack of lead in the fuel as it relates to octane, fuels today are what you call aromatic. These chemicals increase the octane levels but they evaporate quickly and are very susceptible to vapor lock problems in older vehicles. A number of people with stock '55-'57 Chevys have a hard time with starting after letting the car sit for a few days. The fuel has evaporated via the vent tube(s) on the carburetor and the accelerator pump fuel level will normally be low too. A bit of cranking refills the carb and they start. Old lead based fuel did not do this and while you could encounter vapor lock, it was usually question of the fuel line being too close to a heat source. Also, these new fuels are part of the reason that we now have sealed gas tank caps and fuel injectors instead of carburetors. One last item to mention is the fuel tank cap - I honestly do not remember the changeover year, but at least prior to the mid-70's, fuel tank caps were of a vented type. Putting a non-vented cap on these tanks will cause fuel delivery issues too.

[chevynut]

Like I said in the prior thread (don't know why you didn't just keep that one ;)) IF YOUR PUMP IS WORKING CORRECTLY, I believe you have a restriction in your fuel line between the mechanical pump and the tank. Also, your fuel bypass in the filter isn't helping the situation because if I understand it correctly, it causes the pump to have to pull more fuel from the tank than the engine needs and returns the excess to the tank. As it pulls more fuel, the pressure in the line drops.

The pump you're using should provide more than enough fuel for your engine at full-throttle, if it's working as it's supposed to.

To prove this, you could put a small gasoline container in your engine compartment temporarily and feed the pump from that. Then try a full-throttle pass to see if the problem goes away.

[55 Tony]

There is no restriction in the fuel line. When I was messing with the pump the last time and took the tank line off the pump, the fuel ran out since the tank was almost full. I put a container under it and verified that it kept running and wasn't just what was in the hose. I had to lift it higher than the tank to stop it.

I did remove the bypass filter and replaced it with a plastic one so I could see if vapor was coming into the filter. Although I had the same problem before the bypass was installed and the problem actually lessened with the bypass filter. I have not had a chance to test it due to rain.

I am pretty certain the pump works fine. It had the problem from the time I got it on the road and since then the pump and regulator has been changed. I can't put the old pump back on because I cracked the housing from turning the fitting too tight.

[55 Tony]

I forgot to add one thing, I think I should make it my signature file:
HEAT is ALWAYS the common denominator, that would be referring to air temp, not engine temperature. Either unseasonably warm with winter gas, or very hot with summer gas.

[55 Tony]

Like I had said, I got rid of the bypass filter and installed a clear one to show what is happening. The sun came out and it got warm, about 60F, took it out and it acted up much worse than with the vapor bypass filter. Then I came home and with the parking brake on left it idle in drive so under the hood temps would rise. It surprised me how much the gasoline boiled as in the first video. The second one shows how after revving it to cool down, then turning the engine off, again it boiled but it's difficult to see. I thought I had a good video with the engine off but I guess I hit the wrong button. Anyway you can see a few bubbles but there was a lot more than on that clip. It showed me that there was definitely boiling going on, the engine was off so it wasn't sucking air in anywhere. (I don't know what the heck was on the radio!?)lol The first video starts getting good about half way through.

https://youtu.be/RfGK1s_Ohhg
(https://youtu.be/RfGK1s_Ohhg)https://youtu.be/4eVyLw57IKU
(https://youtu.be/RfGK1s_Ohhg)

[55 Tony]

Next time it's warm enough to do this I will try ice or the garden hose on the fuel pump to see if that is where it's getting hot enough to boil.

https://youtu.be/RfGK1s_Ohhg
(https://youtu.be/RfGK1s_Ohhg)https://youtu.be/4eVyLw57IKU
(https://youtu.be/RfGK1s_Ohhg)

[bigblock]

Tony I noticed that you have the filter sitting on the alt. and the fuel line to the carb close to the alt. also. That is not good the alt. generates a lot of heat, try to change that problem first.

[chevynut]

It looks to me like the air/vapor is coming INTO the fuel filter from the fuel line. Look right at the filter inlet and you can see it. So if it's boiling or sucking air, it has to be before the filter. Personally I'm not convinced it's boiling especially since it's supposed to be under pressure in the filter. If it was me I'd eliminate any issues with the fuel line/tank/pickup and everything before the pump by plumbing in a gas container directly to the pump inlet and see if it keeps doing it. Should be an easy and quick check to do. If it goes away, you know where the problem is.

[chevynut]

The larger that line gets, the harder it is to push fuel through it

That is simply not true ;). A larger line has less resistance to flow.


One last item to mention is the fuel tank cap - I honestly do not remember the changeover year, but at least prior to the mid-70's, fuel tank caps were of a vented type. Putting a non-vented cap on these tanks will cause fuel delivery issues too.

Very good point. Pulling a vacuum on the tank will lower the pressure in the entire system.

[55 Tony]

Tony I noticed that you have the filter sitting on the alt. and the fuel line to the carb close to the alt. also. That is not good the alt. generates a lot of heat, try to change that problem first.

It looks it at that angle but the end of the hose at the filter is about 1.25" from the alternator. The lower fitting on the regulator is close, about .25", but with the air from the fan I don't think it makes a significant difference. Anyway it's just a temporary setup so I could see the problem. So far I know it's before the filter.

[55 Tony]

CN, yes the boiling is without a doubt before the filter! That's why I said next time it's warm enough I'm going to try ice or garden hose on the fuel pump and see if it stops boiling.

[55 Tony]

Yes the gas cap is vented and it's not plugged up either. That was verified years ago and checked quite a few more times since. Trust me, if you were here and saw how every time it acts up is heat related, you changed the pickup in the new tank to 3/8 and ran 3/8 line, and a boat load of other things, you would believe it's boiling. It snowed this morning, I don't think it's going to get warm enough today to test it but I'm dying to see what cooling down the fuel pump does.

[chevynut]

I dunno about you but my strategy for troubleshooting a problem is a process of elimination ;). You have a visual indication of the problem that's apparently occurring somewhere between the filter and the tank so it shouldn't be hard to find what's causing it. You can eliminate everything before the pump by plumbing in another temporary container directly into the pump. Just a fuel hose stuck into a gasoline container will work. If that doesn't solve the problem, then you know it's something to do with the pump. If it does, you know the problem is between the pump and the tank. Once you know WHERE the problem is occurring, you can go after that. IMO at this time you don't know where it's occurring, except that it's before the filter.

[55 Tony]

Correct, I know it's before the filter AND always has to do with HEAT. Anyway, it's a lot easier to go for a cruise on the highway and get it good and hot then come home and hit the fuel pump with a garden hose than it is to change the fuel pickup to a gas can. So if the garden hose doesn't stop it, THEN I'll do the hose in a gas can. When going by the process of elimination, one can also logically do the easiest test first.

[chasracer]

That is simply not true ;). A larger line has less resistance to flow.




Yes it does. I meant to say that as a line gets larger the harder it is for a pump to PULL fuel through not push. Thanks for catching that one. >>>

[chasracer]

I am not too sure that the fuel is boiling myself either, it looks more like the normal fuel bubbling we see in carb bowls. Whatever it is, there is a lot of air coming in with the fuel. And just curious but was the filter really hot, gasoline has a starting point of boiling at 90 degrees and should be at full boil somewhere around 200 I think.

[chevynut]

I meant to say that as a line gets larger the harder it is for a pump to PULL fuel through not push. Thanks for catching that one. >>>

Sorry but that's not true either. :) Resistance to flow is the same pulling or pushing.

[chevynut]

gasoline has a starting point of boiling at 90 degrees and should be at full boil somewhere around 200 I think.

100-400F per this site. Not sure why there's such a wide range but it's probably due to so many different compounds in it. I didn't realize it was that low.

https://www.engineeringtoolbox.com/fuels-boiling-point-d_936.html

[chasracer]

Sorry but on that one I know your wrong. The internal size of the line is directly related to the amount of vacuum that has to be placed on the line to get fuel to enter the line.

[55 Tony]

Sorry but that's not true either. :) Resistance to flow is the same pulling or pushing.

No it isn't the same when pulling the liquid uphill. The larger the pipe, pickup, whatever, the more volume. That means it's pulling more weight. Now once the liquid, say gas in a car, once it's sucked up then down again you have a siphoning action and it can level off. In the end after it's primed, it's determined by the height of the fuel in the tank compared to the height of the pump, or to it's final destination. As long as it's going uphill, the larger the line, the harder it is to pull.

[55 Tony]

100-400F per this site. Not sure why there's such a wide range but it's probably due to so many different compounds in it. I didn't realize it was that low.

https://www.engineeringtoolbox.com/fuels-boiling-point-d_936.html

Sort of makes the idea of my fuel boiling a bit more of a possibility doesn't it?

[Rick_L]

You're right about the weight of fuel, but the flow resistance in the line is more important - that's why the higher hp options on a 57 used a 3/8" line instead of 5/16" - or why you'd do that on any high performance situation.

Gasoline fuel is a mixture of hydrocarbons. It's not one hydrocarbon compound which would have more specific and narrower characteristics. For many, many years there's been "winter gasoline" and "summer gasoline". Compounds with higher vapor pressure and low boiling points are used in "winter gasoline". One of the more notable ones is butane, which is the same fuel used in a Bic lighter. It vaporizes at a rather low pressure.

Also, the mixture will vary with elevation. Because of the lower atmospheric pressure, fuel will vaporize more easily at elevation than at sea level. That's also seen in aviation fuel, as the situation is exaggerated.

But think about something Tony - if it's your fuel why isn't everyone in your location having this same problem? They don't, and that indicates something is wrong with your fuel system. It's leaking air into the system, but not leaking liquid out. You aren't the first one that's had the problem. Your challenge is to find and fix it, others have.

[55 Tony]

Rick, do you really think that my system leaks air in, in temperatures as low as 60F with winter gas. Then magically when they switch to summer gas (with a higher boiling point), the air leak goes away until the temps approach 85F? That sure sounds like a boiling problem to me. Unless you know something special about summer gas that doesn't allow my fuel lines to suck air in until it gets much hotter? And in the winter if the temps are below 50F, no air leaks in. And in the summer with temps below about 85F, no air leaks in? Can you explain how that happens? I'd love to know.

[WagonCrazy]

What is the heat source that's causing the boiling? Do you have a fuel line up against an exhaust component?

[Rick_L]

Tony there's no magic. Something is wrong. You could try some race gas or av gas, but that's not what you want to run, so why even do it?

[55 Tony]

What is the heat source that's causing the boiling? Do you have a fuel line up against an exhaust component?

Right now I'm guessing the fuel pump is getting hot from both the heat from the radiator and the heat from the block, although I do already use a 1/8" insulating spacer between the pump and the block. And yes I didn't think of it recently but evidently I'm not the only one with that problem or they wouldn't even make the insulating spacers for it. https://www.cantonracingproducts.com/cgi-bin/commerce.cgi?search=action&category=8510

[55 Tony]

Tony there's no magic. Something is wrong. You could try some race gas or av gas, but that's not what you want to run, so why even do it?

Rick, please excuse my sarcastic outburst, but I've been dealing with this problem for about 5 years now and I keep telling people that it is heat related and they keep ignoring that fact.
I'm thinking of an electric fuel pump near the tank. I have run various kinds of insulation on the fuel line in the engine bay and they didn't help.

[WagonCrazy]

Tony,
Don't mean to be belittling or beligerant here. Just helping you sleuth this problem with some objective thinking...

Heat is common with all engines. The original SBC and BBC never had a heat insulator necessary between the mechanical fuel pump and the block. So if your engine is creating that much heat, then you have to ask yourself why so much heat beyond a standard engine?. Run it and take a cheap Harbor freight laser thermometer and check the block temps around the top of the pistons, bottom of block, etc. Is it more than boiling point (say 250 degrees) near that fuel pump? Is the pump the same temp as the block (when running of course)? I like Laszlo's suggestion of starting simple and diagnosing each component from the carb back.

So, couple of thoughts:
Your video with the engine running and viewing the fuel filter (to me) seems to show not enough fuel flowing thru that filter. I suspect your pump. So pull the feed line to the pump, install a 2 foot length of rubber hose and feed the pump with a small tank of fuel with that line drawing from it. Then shoot a video of the fuel filter with the engine running and compare the flows. If it flows at a higher rate, then you know the fuel pump is being starved somewhere BEFORE the pump. (The lines themself or the tank pickup). If the flow rate is the same, then you know the pump is consistent, but maybe not putting out the 5 to 6 pounds of pressure as it should. Put a gauge on the backside of the pump and run it again and check the pump output pressure.

If your fuel system is not passing enough fuel during driving, then it will eventually starve the carburetor. The bowls will run dry and the engine will stall while driving. Can you confirm that it's running the carb dry during driving? Or is this a "no fuel at warmed up startup" problem?

[55 Tony]

I think I've checked the temp of the block but it's been a while. I know I've tried to check the temp of the fuel pump but those infrared thermometers don't work well on reflective surfaces and it's chrome. In that video there is a tiny bit where you can see my hand down near the pump. I thought the pump felt hotter when it was boiling than when it wasn't but that isn't a great test.

To shoot that video I first ran the car on the highway to get it hot, then let it sit in drive with the parking brake on and the hood closed for a while. I don't think it's that bad when driving, but yes it does run out of fuel going WOT from 1st and if it's hot it will die in 2nd. The accelerator pump in a Q-jet has it's own reservoir that doesn't go dry with the rest of the bowl, so pumping the pedal will give it short bursts of power. So yes I know the bowl is going dry.

Next time it's warm enough here to test it and it's bubbling in the filter, I plan on hitting the fuel pump with a garden hose to cool it down and see what happens. That is a lot easier than changing fuel lines on a "hot off the highway" engine, but I will do it if the cold water doesn't stop the bubbling.

Just to catch you up in case you missed it, I have changed pumps and ran an all new 3/8" line with no improvement. A while back, years ago, I cut the lower part of the baffle next to the radiator and made a half ass baffle to direct cool air to the pump, and that helped a lot, but only on the highway. That isn't in place now, I forget why/when I took that out. Thinking of that now I suppose I could install another tube similar to the cold air intake but one that blows directly on the pump. Yes it would only help while moving, but it would be much more efficient than the baffle I had in there before. I have some real ugly galvanized flexible tractor trailer exhaust pipe I could try it with and if it works get some shiny stuff like the air intake.

[BamaNomad]

Could this another case where the 'chrome' is a part of the problem??? :)

[markm]

Could this another case where the 'chrome' is a part of the problem??? :)

I was wondering the same. what kind of pump is it.

[Troy]

My dad always says...If it don't go chrome it!!! This seems to be if it's chrome it don't go!!! :D

[55 Tony]

What? What would the chrome do? Oh, maybe the seal would leak sucking in air? I have to run out for some things and I'm taking the 55. See how well it runs today that it's cold out.
It's a Holley pump, and the same one before it gave the same problem.

[bigblock]

Tony you said you been fighting this problem for 5yr's, is it with the same fuel pump? the way you say it acts up sounds like it runs out of gas because the pump isn't keeping up the gas volume you need. You said you changed the line from the tank to the pump was it with hose or tubing , if its hose are the clamps to tight? If I had this problem for 5yrs I would look at the pump because it looks like it is pumping air because of the bubbles. The check valve in the pump seems to misfunction after its running awhile.

[chevynut]

Sorry but on that one I know your wrong. The internal size of the line is directly related to the amount of vacuum that has to be placed on the line to get fuel to enter the line.

I'm not following you on that one. Resistance to flow is a function of cross-sectional area and surface condition of the inside of the line. The larger the line, the less pressure drop no matter if you're pushing or pulling the fluid. It's the same pressure drop either way and is dependent on flowrate.

What does vacuum have to do with it?

A column of a fluid in a 1/4" line has the same pressure as the same fluid in a 1" line, as long as the height of the line is the same. The vertical distance is all that matters, not the column size. A 1 acre lake with an outlet 100 feet below the surface exerts the same pressure as a 10,000 acre lake with the outlet 100 feet below the surface.

[chevynut]

No it isn't the same when pulling the liquid uphill. The larger the pipe, pickup, whatever, the more volume. That means it's pulling more weight. Now once the liquid, say gas in a car, once it's sucked up then down again you have a siphoning action and it can level off. In the end after it's primed, it's determined by the height of the fuel in the tank compared to the height of the pump, or to it's final destination. As long as it's going uphill, the larger the line, the harder it is to pull.

No that's is not true. Line size has nothing to do with pressure of a fluid. As I said above, the only thing that matters is the height difference between the inlet and outlet. That's precisely why a siphon works.

Notice in the formula on this page the width or diameter of the column is not included...it's because it's irrelevant.

https://www.engineeringtoolbox.com/hydrostatic-pressure-water-d_1632.html

[chevynut]

Sort of makes the idea of my fuel boiling a bit more of a possibility doesn't it?

Except after the pump the fuel is under pressure, so it's less likely to boil. And Rick's comment about why doesn't everyone (running a carburetor) in your area have the same problem? EFI systems don't have as much of a problem with vapor lock since the system is under much higher pressure.

[55 Tony]

No that's is not true. Line size has nothing to do with pressure of a fluid. As I said above, the only thing that matters is the height difference between the inlet and outlet. That's precisely why a siphon works.

Notice in the formula on this page the width or diameter of the column is not included...it's because it's irrelevant.

https://www.engineeringtoolbox.com/hydrostatic-pressure-water-d_1632.html

You know, I was going to ask you what is harder lifting an ounce of water or a gallon, but it hit me. Although the line is larger therefore there is more weight to pull up, the surface area is also greater. So if the pump is pulling on an empty line with the end in liquid, the larger line would have the same vacuum psi, but it would also have more surface area so the same vacuum will indeed lift the fluid the same whether it's a 1/4" line or a 1" line. You are right, (and I don't mind admitting it).

[55 Tony]

I went for a ride and since it was colder today, it didn't act up at all. Besides not running out of fuel and stalling, the fuel pressure didn't drop either. When I came home I looked under the hood and saw just a few bubbles then it stopped, so I closed the hood and left it idle in gear for about 1/2 hour and checked on it. Yes I know the water went all over the place, but the garden hoses are put away for the winter. I'm certain I'd have the same results with water only on the pump. And before someone says that "the water sealed the leak so the bubbles stopped", watch again and notice how long it takes for the bubbles to stop. That's because the fuel is on the bottom of the pump and it took a while for that to cool down.

I say it was BOILING!

And I don't think anyone can convince me otherwise.

https://youtu.be/Jg8-z3nHjbE
https://youtu.be/ee-3spbjugY

[55 Tony]

Tony you said you been fighting this problem for 5yr's, is it with the same fuel pump? the way you say it acts up sounds like it runs out of gas because the pump isn't keeping up the gas volume you need. You said you changed the line from the tank to the pump was it with hose or tubing , if its hose are the clamps to tight? If I had this problem for 5yrs I would look at the pump because it looks like it is pumping air because of the bubbles. The check valve in the pump seems to misfunction after its running awhile.

BB, the pump was replaced and the problem stayed the same. And if the check valve was the problem, it just wouldn't pump well, it wouldn't allow air to enter, it would just let some fuel to go backwards.

And as far as this going on for 5 years, keep in mind that I had this problem ALMOST under control with a different fuel filter made to bypass vapor. It would only act up under extreme conditions. I changed filters to purposely make the problem worse, so I could track it down and hopefully eliminate the problem completely. I believe I found the problem.

[bigblock]

Good luck with your problem.

[BamaNomad]

What? What would the chrome do? Oh, maybe the seal would leak sucking in air? I have to run out for some things and I'm taking the 55. See how well it runs today that it's cold out.
It's a Holley pump, and the same one before it gave the same problem.

No, I was referring to the fact that chrome doesn't dissipate heat as well as a rough black surface... and you think the problem is heat related... normally a mechanical fuel pump would only heat from being in proximity to the block, not from it's own generated heat (which should be minimal).

[55 Tony]

My plan is back to an electric pump near the tank, and the fuel line in the engine compartment to be as short as possible. Maybe insulated.

[WagonCrazy]

I say it was BOILING!

And I don't think anyone can convince me otherwise.

Observations on the 2 latest videos (with the engine warmed, and idling):
Video 1- the fuel filter is only 1/3 full while running. Same as the first 2 videos you posted. As you pour water on it, it starts to gradually fill more.
Video 2- the fuel filter is nearly full to capacity as you are pouring water on it.

What changed between these 2 videos?

[WagonCrazy]

My plan is back to an electric pump near the tank, and the fuel line in the engine compartment to be as short as possible. Maybe insulated.

Found this guys answer in another forum (on the same subject of overheating fuel and stalling)...

I'm running a clear filter between the carb and the fuel pump and I would get a relatively constant stream of bubbles even before the engine got hot. It was also down on power. It was sucking air into the fuel line between the pump and the tank.

So If I were you, I would invest time under the car and check all your connections and replace any rubber hose over a few years old at this point. I think you are drawing air into the lines somewhere, and that is contributing to the bubble situation...
Just my 2 cents. Go for the most obvious things...as they are often the source of the issue.

[55 Tony]

What changed between these 2 videos?
Oh good gawd.
What happened was again my finger slipped off the camera button (it's an old Kodak camera with a movie mode (MOV. file) I just looked at the files and in the file info is a difference of 38 seconds. Subtract the length of the 2nd video, 35 seconds, and you have a gap of 3 seconds where I was fumbling with the camera and trying to re position the 1 gallon can. That is what happened.

[55 Tony]

Found this guys answer in another forum (on the same subject of overheating fuel and stalling)...

I'm running a clear filter between the carb and the fuel pump and I would get a relatively constant stream of bubbles even before the engine got hot. It was also down on power. It was sucking air into the fuel line between the pump and the tank.

So If I were you, I would invest time under the car and check all your connections and replace any rubber hose over a few years old at this point. I think you are drawing air into the lines somewhere, and that is contributing to the bubble situation...
Just my 2 cents. Go for the most obvious things...as they are often the source of the issue.

Did the video show you nothing? Or do you think I somehow cheated it? Gos for the most obvious thing? J.C., how many times must I say that I replaced the entire line from sump to pump and had the same exact problem. There is no fricken way that much air could leak in at idle without any fuel leaking out when not running.

[55 Tony]

I'll make a wager with anyone here, $1,000. cash. Come here, lay out your money and try to say the cold water isn't cooling the fuel pump and stopping the gas from boiling. Well get some kind of honest judge/s. That's $1000 cash to you if the cold water doesn't stop the gas from boiling when put on the fuel pump, not touching the filter, $1,000 to me when you see it does exactly as I've been saying.

[chevynut]

My plan is back to an electric pump near the tank, and the fuel line in the engine compartment to be as short as possible. Maybe insulated.

It'll be interesting to see if that works. Why? Because the mechanical pump will still put out the same pressure, and the same fuel flowrate. I understand those Holley pumps are internally regulated. So theoretically you'll still have the same problem because the fuel will get just as hot, right? That is UNLESS the problem is occurring before the pump. The electric pump will push fuel to the mechanical pump, instead of making the mechanical pump pull it. So if you're vaporizing the fuel in the line before the pump, or sucking air somewhere, the electric pump will cure it.

I'd really like to know what's going on here, so I'd ask that you just change one thing at a time so we can see how the problem is affected by that change. This has been interesting to me. ;)

[55 Tony]

CN, I'm not running it through the mechanical pump, that would make the fuel hot like it is now.

[markm]

I can run cut the timing and run 87 pump gas with fewer issues than Tony, but I won't. My overkill system was not hard or expensive. Truth be known the real reason for the sump was I cut the bottom out of the 60 year tank to clean it out inside.

[55 Tony]

I can run cut the timing and run 87 pump gas with fewer issues than Tony, but I won't. My overkill system was not hard or expensive. Truth be known the real reason for the sump was I cut the bottom out of the 60 year tank to clean it out inside.

I don't get it? Is there supposed to be some correlation between octane and boiling point? Even if I had the same sump my fuel would boil just the same.

[BamaNomad]

My money is on a pinhole in the fuel line near the tank... I had a similar problem keeping my '57 sedan running; First I changed the pump.. no change.. then I figured the gas tank had clogged up from sitting, so I decided to put a new tank/pickup in it.. While replacing the tank I found a pin hole in the hard line near to the tank where the line had 'almost crimped'... it never leaked when sitting (the pinhole was above the tank and may have been above the fuel pump as well... I cut the line where it was leaking and put in a neoprene rubber line stopgap (it's still that way and no more problem...)...

[55 Tony]

My money is on a pinhole in the fuel line near the tank... I had a similar problem keeping my '57 sedan running; First I changed the pump.. no change.. then I figured the gas tank had clogged up from sitting, so I decided to put a new tank/pickup in it.. While replacing the tank I found a pin hole in the hard line near to the tank where the line had 'almost crimped'... it never leaked when sitting (the pinhole was above the tank and may have been above the fuel pump as well... I cut the line where it was leaking and put in a neoprene rubber line stopgap (it's still that way and no more problem...)...

What I didn't say is that yesterday I tested it again and used a hose that only hit the pump. Again once the pump cooled down it stopped boiling. In this one it starts off where you can't really see any liquid fuel at the beginning. Can you make that a $1000 money order so I can get the cash at the PO? I may be depositing over $10,000. a day and the bank has to report that to the government. :p

https://youtu.be/DiORzKq0Kt8

[BamaNomad]

Maybe you have a 'devil' car and there's no solution? :)

[chevynut]

CN, I'm not running it through the mechanical pump, that would make the fuel hot like it is now.

Sorry, I misunderstood. ;)

But it would be a good way to prove your theory. If you left everything as it is now but installed the electric pump and the problem still exists, it proves that the fuel is boiling in the fuel pump. If the problem goes away, it proves it's before the pump.

[chevynut]

Here's something interesting :)

https://www.youtube.com/watch?v=cadNfSNi_Oc

[55 Rescue Dog]

Good video.

[WagonCrazy]

According to this video, it looks like an in-tank electric pump (and removal of the "old boiler" mechanical pump) is the way to go here.

[55 Rescue Dog]

It's not going to be a cheap fix, especially if you do it right, but it would probably be worth it to make it run right. I'm glad I can still get good ole 110 octane leaded race gas here. Lots of dirt track racers around. My 11:1 engine loves it, although it is 8 bucks a gallon, but mixed 50% with ethanol free gas, and I'm lucky if I use 2 tanks in a summer.

[55 Tony]

Here's something interesting :)

https://www.youtube.com/watch?v=cadNfSNi_Oc

Damn, I wish I saw that years ago. Just saw it now. Today I installed an in line Holley pump and the only connections where it could have leaked air in are still there. I had the pump running with the engine off for about an hour with no bubbles, oh, and right now I have the clear filter first and the bypass filter in again before the carb because the pump being dead headed did slightly raise the temp of the fuel in the pump which was no problem now, but I figured when it's 90F outside it could be a problem. Left it running that way for another hour with the engine running for about 1/2 hour and got no bubbles in the filter. Not a single one. I didn't have a lot of time to spend on it so it's not wired properly yet, I just ran the hot wire to the battery. I have some small motor mounts that are a 1/4" stud on each end and about 3/4" of rubber in the middle, I'm going to try those to see if I can quiet the pump just a little more so I can't hear it with the engine running. I can hardly hear it now but it's still annoying. Without a regulator I'm getting 6 to 6.5 psi which if it was too much I think would have showed up while idling so I may be OK without a regulator.

CN, it's nice you believe me now, but after all those posts, the fact that it took that video for you (and others?) to believe me still makes it a big insult.

[chevynut]

CN, it's nice you believe me now, but after all those posts, the fact that it took that video for you (and others?) to believe me still makes it a big insult.

No insult, I had no idea gas would boil at such low temps. It was my lack of knowledge on the subject, and not being able to see exactly what was going on. I learned something here too. ;)

[56Mark]

A big insult? I have been following this thread with interest and went back re-read it all. I didn't see anything insulting. Yes, others were questioning you and did not think it was boiling, probably because they have not had that happen to them. I was betting on an air leak before the pump too. I learned a lot from this thread, like how low of a temperature gas will boil and how to fix the problem if I have it happen to me. Cnut pretty much confirmed what you were saying and you took it as an insult that we just didn't believe you. I think everyone was just offering input to help solve the problem. Anyway, glad you got it fixed and thanks for posting the problem, it was informative.

[55 Tony]

Well maybe I used the wrong or too strong a word. It isn't as if I'm going to go home and cry to my Mommy.

I do have the satisfaction of knowing I was right and not listening to everyone who kept suggesting other ideas or telling me I'm on the wrong track.

My biggest letdown is that no one took my bet!

[BamaNomad]

Well Tony, we all thought you were looking for 'solution possibilities', whereas you apparently believed you were conducting a 'boiling gas seminar' for all us ignorant folks... :)

[55 Tony]

Oh, so the guy in the video CN posted was conducting a "boiling gas seminar"? Thinking it over I guess he was, and I was also conducting a boiling gas seminar. But after repeated attempts, no one believed the teacher.

[55 Rescue Dog]

Oh, so the guy in the video CN posted was conducting a "boiling gas seminar"? Thinking it over I guess he was, and I was also conducting a boiling gas seminar. But after repeated attempts, no one believed the teacher.
Being a part time industrial electrical instructor at a local college, you might want to brush up on your teaching skills a bit. :)

[55 Tony]

Being a part time industrial electrical instructor at a local college, you might want to brush up on your teaching skills a bit. :)

Yes, I'll have to go new wave "old school". If they don't believe me and keep up with the wrong answers, get out the stun gun and zap some sense into them. And you do realize that I wasn't the first to call me a teacher, I was just listening to one of the smart alec brats in class. Truthfully, in the three jobs I had before being self employed, the bosses asked me to teach the other repair techs. I failed the first time and told the next two that I can't teach, I can only diagnose and repair.

Dictionary
smart al·eck
ˈsmärd ˌalək/
informal
noun
noun: smart alec
a person who is irritating because they behave as if they know everything.

[Florida 57]

Here's something interesting :)

https://www.youtube.com/watch?v=cadNfSNi_Oc

I am going to assume that do to time constraints placed on the video they did`nt show or mention cleaning the tank after the cut was made.They cut the hole from the bottom mentioning the shavings but then de-burr the hole right side up allowing the shaving to fall right in the tank.The pictured Aeromotive pump is not inexpensive either and is a nice setup.

[Rick_L]

Way better than modifying a crummy perhaps doubtful old tank (along with the safety hazards) is to just replace the tank with a Tanks Inc. tank and their in-tank pump. Tanks Inc. and Aeromotive sell the same tank, but I think it's cheaper at Tanks Inc. The tank is essentially the same as a stock tank except it's set up for the in-tank pump. The fuel pump setup certainly is far cheaper and very adequate from Tanks Inc. You will need a regulator and return line with this setup, with the pressure set for a carb. You could place it near the tank to avoid having to run a return line the length of the car.

[55 Tony]

Anyone have a simple guesstimate calculation for gph needed for a certain HP? Or damn, the internet has millions of online calculators but I can't find one for gph of fuel & HP. I bought the Holley Red pump and although it hasn't starved for gas yet, going WOT drops the pressure from 6.5psi to 3.5 psi. I haven't gone a 1/4 mile but I think it will make it. When I bought the Red pump I was looking at the free flow gph, not the 7psi flow rate. Funny thing is that even if I clamp off the return line it acts the same exact way.

[chevynut]

I think I posted this in your first thread.

http://www.onallcylinders.com/2013/05/16/what-size-fuel-pump-do-i-need-your-top-tech-questions-answered/

"There’s a simple formula to calculate GPH or LPH (liters per hour), but there are some variables to this formula, depending on your application. Norm Koval, a team leader in the Summit Racing technical department, typically follows this formula as laid out by the air/fuel experts at Holley:
Optimal GPH = (Max. HP x BSFC) / 6
Optimal LPH = (Max. HP x BSFC) / 1.585
In order to make the proper calculation, you need to determine your variables for this equation, starting with your vehicle’s maximum horsepower (Max. HP). You can determine this by having your vehicle dyno tested (http://www.onallcylinders.com/2012/05/11/dyno-duel-engine-vs-chassis-dynos-what-you-should-know/)or by making a reasonable horsepower estimate based on the manufacturer’s advertised horsepower plus a conservative estimate of power gains made by aftermarket modifications.
The second variable in the equation is BSFC, or brake-specific fuel consumption. BSFC is a measurement of the amount of fuel consumed per unit of power produced. According to Holley (http://www.summitracing.com/search/brand/holley), an engine typically requires .5 pounds of fuel per horsepower every hour at wide open throttle. However, this number generally applies to naturally aspirated engines."

[chevynut]

Here's the flow versus pressure graph from Holley:

https://images.holley.com/583x/12-801-1chart.jpg

https://www.holley.com/products/fuel_systems/fuel_pumps_regulators_and_filters/fuel_pumps/carbureted_fuel_pumps/carbureted_electric_fuel_pumps/parts/12-801-1

[55 Tony]

Hmm, if I did that correctly, guessing a little high at 500HP, I get 41 gph and the pump is supposed to be good for 67 gph at 7 psi.

[chevynut]

the pump is supposed to be good for 67 gph at 7 psi.

I don't see where you get that. The graph from Holley shows about 50 GPM at 5 PSI.

[chevynut]

Here's Holley's graph for their Blue pump:

https://images.holley.com/583x/12-802-1chart.jpg

[55 Tony]

So do you think the pump is faulty or rated wrong? Or have I screwed up the calculation?

[55 Tony]

I don't see where you get that. The graph from Holley shows about 50 GPM at 5 PSI.

https://www.summitracing.com/parts/hly-12-801-1

[chevynut]

Your calculations are correct (I get 41.67) and the pump should put out around 5PSI there according to the graph. It looks to me like you should have used the blue pump, if their graphs are correct and you want 7 PSI.

[55 Tony]

Oop's, summit says 67 at 5 psi, not 7 psi. Still I'm going down to about 3.5 psi.

[55 Tony]

Your calculations are correct (I get 41.67) and the pump should put out around 5PSI there according to the graph. It looks to me like you should have used the blue pump, if their graphs are correct and you want 7 PSI.

I think 5psi would be fine, but it's going down to 3.5psi

[chevynut]

I think 5psi would be fine, but it's going down to 3.5psi

If you're measuring that at the engine, you have pressure drop in the lines between the pump and the engine.

[55 Tony]

If you're measuring that at the engine, you have pressure drop in the lines between the pump and the engine.

I'm measuring it at the engine but before the two filters (one clear to see bubbles, and one with the bypass, just temporary). I don't want to get into a war again, but I really don't think it's loosing that much in the line, but anything is possible.

[chevynut]

http://fuelab.com/wp-content/uploads/2015/05/Graph-A-copy.jpg

http://fuelab.com/fuel-line-size-vs-pressure-drop/

[chevynut]

What do you have between the pump and the tank? What size fittings?

[55 Tony]

3/8" fittings, 8" 3/8 hose, 8' 3/8" steel line, and 8" 3/8 hose to a 3/8 T with the pressure gauge. Steel line has, I don't know if there is a name for it, but the ends like a bubble from starting to make a double flare so the hose is tight.

[chevynut]

Sounds like you have all the right fittings, if none of them have restrictions. If everything has at least 5/16" ID, which is about the ID of a 3/8" steel line, you should be good. How did you tap into the tank, out of curiosity? Notice that with a continuous smooth AN6 line the chart says you'll get around 1PSI drop in the length of the car at your max flowrate. I'm not sure that a drop in pressure really affects a carburetor that much.....all you have to do is keep the bowls full.

[55 Tony]

You got me on tapping the tank. I used the same standard pick up but 3/8. Once the line is primed I don't think it should make a difference due to the siphoning effect. I was surprised at how fast the pump primed itself. The fuel that was still in the front of the line going to the clear filter came in almost instantly, certainly less than 1 second anyway. If I would use the drain plug at the bottom of the tank, it's kind of small and I'm afraid all that will fit is a 1/4 inch fitting, and it looks like fine thread. Maybe the whole thing is not an issue. It's been fine so far, but I haven't gone a 1/4 mile.

[55 Tony]

I don't know what to think of this pump? I don't know if this is new or it did it before, but at maybe 1/4 throttle at most, the pressure goes down to 4psi. But I did a few 1/4 miles and it went down below 4, maybe 3, but the engine didn't skip a beat. I got home and put a jumper wire to leave it running to see if it lasts 3 or 4 hours. At idle with the bypass clamped off and sitting for a few minutes it started to loose pressure. It started to flutter a little, then a lot. Took the clamp off the bypass hose and it went up at least 1/2 psi and stayed a steady. Looks like it was starting to boil without the bypass. The next couple months will test it good since we don't get summer gas until June.

Doing a search in the EPA, I found that they raised the REID pressure in a lot of TN counties. A lot of people are going to be boiling, and it goes against the EPA's normal ways because gasoline vapors pollute much more than combusted gasoline. Maybe it's an attempt to rid the country of carbureted vehicles?

[55 Tony]

Since my last post on this, I sent the flaky Holley pump back. The pressure kept changing. I replaced it with a Carter. Nice unit and very nice sound isolation included. The whole thing hangs from 3 rubber mounts and there is no metal to metal contact, unless the rubber mounts wear out. It actually circulates the fuel through the motor to keep it cool, the holley didn't.

Now the bad. It only puts out 4.5psi. Even dead headed with a gauge in the line from the pump. Good part is that unlike the holley that dropped pressure when going WOT, this one stays at 4.5psi. The specs at Summit say 4.5 to 8psi and Carter is sticking to it. They say if it's deadheaded and putting out 4.5psi and still putting out 4.5psi at WOT, it's within specs.

But this doesn't seem to be a problem, it's running great at 4.5psi. Today it was about 75F and with winter gas I took it on the highway about ten miles at 80mph (street tires), stopped at an exit and in a hot parking lot left it idle in gear for ten minutes. Temp went up over 210F. Drove 100 feet to the on ramp and WOT, didn't skip a beat. That combination would have had it starving for fuel big time with the mechanical pump boiling the fuel.

I'm still in the "I told you so" stage but I doubt I'll get anyone to admit they were off base and I was right all along. :)

[Rick_L]

Glad it works for you.

You're right in a way, what you had wasn't working, and now what you have is working. But something was amiss with your mechanical pump setup, somewhere. They don't ALL boil the fuel!

[55 Tony]

Glad it works for you.

You're right in a way, what you had wasn't working, and now what you have is working. But something was amiss with your mechanical pump setup, somewhere. They don't ALL boil the fuel!

Oh my God Rick! You are one stubborn guy. Did you see the video of the cars coming in the speed shop with the same exact problem? No kidding they ALL don't boil the fuel! Do all cars with automatic transmissions have problems in the first 10,000 miles? No, but some do. Do all engines start burning oil for no apparent reason? No, but some do. Do all tires go flat due to a leak in the rim? No, but some do. With all the info I gave, especially when I said over and over and over that it has to do with heat, you just kept ignoring the symptoms and drawing your own conclusion, which was WRONG, in a very BIG way. Be a man and admit it.
I was "right in a way", what a joke. What I did was diagnose a very rare problem and found a way to fix it. Anyone can find the common problems that happen in all cars.
Uh oh, I may have gone too far, my head is having trouble fitting through doorways. LOL

[chevynut]

It's a lot easier to diagnose a problem with a car right in front of you than to have someone describe symptoms, change them, feed bits of information at a time, and ask someone to diagnose it over the internet. I agree with Rick that something wasn't right with your fuel system and you never really did figure out the true root cause. You changed too many things at one time to say precisely what was causing the problem. There's probably guys in your area with carbs and mechanical fuel pumps using the same exact gas that don't have the same problem....so why not?

Yes it looked like the fuel was "boiling" in your pump and/or fuel lines and you fixed it by changing to an electric pump. But can you say exactly WHY it was "boiling"? I personally don't know if you can based on all the things you changed. Was the pump too hot? Were you pulling a vacuum on the fuel line? Was your fuel bad? Why was the fuel still boiling on the pressure side of the pump? Or was the line to the pump hot enough to vaporize the fuel?

Anyhow, I'm glad you got it fixed too. ;)

[55 Tony]

It's a lot easier to diagnose a problem with a car right in front of you than to have someone describe symptoms, change them, feed bits of information at a time, and ask someone to diagnose it over the internet. I agree with Rick that something wasn't right with your fuel system and you never really did figure out the true root cause. You changed too many things at one time to say precisely what was causing the problem. There's probably guys in your area with carbs and mechanical fuel pumps using the same exact gas that don't have the same problem....so why not?

Yes it looked like the fuel was "boiling" in your pump and/or fuel lines and you fixed it by changing to an electric pump. But can you say exactly WHY it was "boiling"? I personally don't know if you can based on all the things you changed. Was the pump too hot? Were you pulling a vacuum on the fuel line? Was your fuel bad? Why was the fuel still boiling on the pressure side of the pump? Or was the line to the pump hot enough to vaporize the fuel?

Anyhow, I'm glad you got it fixed too. ;)

Yes I do know the problem. The fuel pump was heating the fuel to over it's boiling point. No "hot lines" boiling it. I don't know what you mean about changing too many things at once. I changed the fuel pump to an electric one mounted in a cooler area and the problem went away. Bad gas? Bad gas for years and years from 20 or more different gas stations? All the info is in the thread, but it was quite a long thread and I don't expect anyone to re-read it all.

[markm]

I have to agree with both Cnut and Rick, really don't believe a pump was heating fuel. Too many cars have driven million of miles without this issue.

[55 Tony]

I have to agree with both Cnut and Rick, really don't believe a pump was heating fuel. Too many cars have driven million of miles without this issue.

Have you watched this video? No it's not mine. Do you believe it or do you think they are wrong also?

https://www.youtube.com/watch?v=cadNfSNi_Oc

[55 Tony]

And by the way, cnut found that video and he believes it. Rick? Who knows if he saw the video or not, if he did he would probably deny it.

[Rick_L]

I saw the video, and I believe you can make gasoline boil if you try to. And maybe yours did too. But you didn't find out why did you? Again, they don't all do that, in fact very few. Yours.

[55 Tony]

I saw the video, and I believe you can make gasoline boil if you try to. And maybe yours did too. But you didn't find out why did you? Again, they don't all do that, in fact very few. Yours.
Mine, and the ones in the video, the ones in other videos if you do a search there are lots of them using just a bypass, the same thing I did a few years ago and it worked 95% of the time but I was going for 100%, and the other ones that are fixed the same way that we will never know about, and the thousands and thousands more that haven't figured it out yet. And how many thousands have bought these in an attempt to fix their boiling problem. https://www.summitracing.com/search/part-type/fuel-pump-insulators?SortBy=Default&SortOrder=Ascending&tw=fuel%20pump%20in&sw=Fuel%20Pump%20Insulators

Wow Rick! 17 different fuel pump insulators being sold at Summit. Sounds like they are in high demand! Sure, but you still think I'm the only one with fuel boiling issues. I looked at the first one and the first sentence in the review states "I purchased this product as one step in reducing my fuel boiling issue." Sure Rick, I'm the only one. And the first review of the second one states "This insulator is one of the things that helped stop my gasoline vapor lock problem. It really works 100 times better if you can divert hot radiator air from the pump and divert cool air to it." (diverting the air was another trick I did for a while, would you like to see where I cut off the bottom of the radiator baffle to allow cool air to the pump?) Sure Rick, I'm the only one. I'd go on but your ignorance about this simple problem isn't worth my time. Well maybe if you keep giving me excuses to show your ignorance on the subject, I may chime in again. Like I've posted more than a couple times, you are a seemingly intelligent person, but when you are dead wrong you simply don't have the gonads to admit it.

You are really sounding like an a$$hole. Yes Rick, once again I will tell you why since you keep forgetting. It boiled in the fuel pump because the temperature got above the boiling point of the gasoline. That is what caused the problem for me and many thousands, maybe 10's of thousands of other people with the same problem.

[Rick_L]

You're not the only one. But you're the only one on this forum that didn't find what the REAL problem is.

Those "insulators" don't do anything. Bypasses are not the answer either.

Thing is, you should be happy that your problem is "solved" instead of being bitter.

[55 Tony]

I have to agree with both Cnut and Rick, really don't believe a pump was heating fuel. Too many cars have driven million of miles without this issue.

Please refer to my latest reply to Rick and try thinking before you post.

[Rick_L]

Let's see. I'm an asshole because I disagree with you? You post a problem seeking solutions to your fuel problem. You then argue with those who reply. Who's the asshole here?

If you don't think I'm right, then just ignore what I said. Simple solution.

[chevynut]

I think I'd be more convinced if you would have installed the electric pump and run it through the existing fuel line to your existing mechanical pump without any other modifications, as I suggested. If the problem went away, it was NOT the mechanical pump getting too hot. If the problem remained, I would have agreed the pump was getting the gas too hot. You changed the fittings in the tank, the pickup location, the line between the pump and the tank, and re-routed the line to the carb. To prove root cause you change ONE thing at a time. To "shotgun" the problem and just fix it, you can change everything you want to.

The video showed a similar problem as yours. But again they changed a bunch of things to fix it.

[55 Tony]

It sure must be a coincidence that they sell thousands of fuel pump insulators for a problem that doesn't exist. Sorry I called you an asshole, you are correct Rick.

[55 Tony]

I think I'd be more convinced if you would have installed the electric pump and run it through the existing fuel line to your existing mechanical pump without any other modifications, as I suggested. If the problem went away, it was NOT the mechanical pump getting too hot. If the problem remained, I would have agreed the pump was getting the gas too hot. You changed the fittings in the tank, the pickup location, the line between the pump and the tank, and re-routed the line to the carb. To prove root cause you change ONE thing at a time. To "shotgun" the problem and just fix it, you can change everything you want to.

The video showed a similar problem as yours. But again they changed a bunch of things to fix it.

I don't know where you came up with that. I didn't change any fittings at the tank. I cut into the existing fuel line and installed the pump, then bypassed the mechanical pump. But like I told Rick, you are probably right, they sell thousands of fuel pump insulators because people think they look cool, not due to boiling fuel. You are correct.