Nomad final assembly

[chevynut]

I was looking at the changes I have to make and was surprised the HP EFI and the Terminator X both have 40A fuses and 10 gauge wires for the main power leads. WTH? I've been running my C950 with a 10A fuse. Both drive the injectors and fuel pump externally and the ignition coil is powered separately. Both run the WBO2. Why so much current draw?

[WagonCrazy]

looks like lots of room in there. if the standard harness isn't long enough, then buy the 15 foot one and do the terminations yourself. That will make the installation more clean. What you have done to date is VERY CLEAN looking. Stay with it Laszlo. You actually have the benefit of time here, since its 2024 in a few weeks and it's not done yet. Might as well get it set up with the most modern ECU you can get right now.

[chevynut]

Today I removed the upper intake manifold and injector retainers. There's one fuel rail for all 8 injectors. I also installed a new oil filter and cleaned and gapped the spark plugs. I will need new gaskets for the manifold.

I've been looking at the injector harness connections. I have my 502 injector harness wired for the C950 that came with a 5-pin Weather-Pack. There's one wire for power and four to fire injectors. I have injectors wired together in pairs in the harness, 5-7, 2-6, 8-4, 1-3. I was told pairing didn't matter, so I wired adjacent ones together. I noticed the new ECUs have 8 injector wires and a 10-pin connector to the injector harness. Two connections are for power, and eight to fire the injectors individually for sequential injection. However, I have no cam sensor so I don't see why it matters whether I fire one at a time or two at a time.

I'd rather not buy or make a new injector harness. They don't make one for the RJ502 anyhow. I think I have two options....one is to just replace the injector connector on the new main harness with the 5-pin Weather-Pack and wire every other cylinder output. The other is to split my injector harness and use the 10-pin connector to match the main harness. But here's the weird thing.....

https://www.holley.com/products/fuel.../parts/570-202

The above is the Holley Injector Sub Harness Connector they sell. Notice there's only five contacts.

I'll probably do the second option anyhow once I figure this out. Since I can fire one injector at a time it makes sense to do so. The rest seems pretty straightforward so far. The new and old systems are fairly similar.

[Tabasco]

When my wife and I did the 7 year restoration on her 56 convertible, the new engine was installed 3 years before we tried to start it. I went to Dollar Tree and bought a squeeze bottle. I put gas in the bottle, squeezed gas in the carburetor vents to fill the bowls. I stepped on the gas pedal once to send a squirt of gas to the carb and set the electric choke. I turned the key and it fired right up. I am glad we used old technology on our build.

[chevynut]

When my wife and I did the 7 year restoration on her 56 convertible, the new engine was installed 3 years before we tried to start it. I went to Dollar Tree and bought a squeeze bottle. I put gas in the bottle, squeezed gas in the carburetor vents to fill the bowls. I stepped on the gas pedal once to send a squirt of gas to the carb and set the electric choke. I turned the key and it fired right up. I am glad we used old technology on our build.

When i first fired my 502 in the chassis, I didn't even have to touch the non-existent gas pedal. I turned the key and it fired right up.

When I start my snowmobiles, the two with antiquated carburetors take forever to fire up after sitting all summer. The two with EFI crank a couple of times and fire.

My two ATVs with carbs take constant work to keep them running right. The ones with EFI fire every time and run and idle perfectly.

Sure wish I could get rid of all those carbs.

[WagonCrazy]

Sure wish I could get rid of all those carbs.

Amen to that, brutha! Carburetors are a PITA, now that we have modern FI systems. So many advantages with Fuel Injection. You just got to be willing to learn and adapt.

[chevynut]

I've been doing a bunch of research on Holley's EFI and I made a decision to go with the TeminatorX ECU and a custom harness. Their standard harnesses are only 88" long from the TPS to the ECU connector for a GM TPI harness. The ECU won't fit where the C950 is, so I'd have to cut out the bottom of my console box to put it there. That's what made me decide to go with their un-terminated 15 foot harness and add my own connectors. I can also locate the ECU wherever I want it, so it's going under the rear seat. The TerminatorX has an integrated spark control and integrated WBO2 controller, so I can get rid of my stand-alone modules.

The TerminatorX ECU is only $654 while the HP EFI ECU is $1483. I can't see paying $800 more for the few additional features of the HP EFI. Both are programmable via laptop. Both are self-learning. The TerminatorX requires a new Bosch 4.9 O2 sensor.

One thing I found out is the ECU fires sequentially, so I will have to re-do my injector harness to split the paired injectors. It should be easy to do and I won't have to completely build a new harness from scratch.

Then the "might as well" got me. While the new ECU fires injectors sequentially, it's not timed to the cylinders. I thought I'd need to add a crank and cam sensor to enable that, but Holley/MSD makes a "dual sync" distributor with cam and crank sensors in it that sends the signals to the ECU. This way you get timed, sequential injection. I'm using a cheap GM computer-controlled distributor so this will be an upgrade too.

My injectors should be here Monday, and I plan to order the rest of the parts this week. I'm heading to Montana for 2 weeks over Christmas so I will have to wait til I return to start working on the wiring.

[chevynut]

Well you're not going to believe this .

With the upper intake off I can see each of the injector ports in the lower manifold. So I decided to run the fuel pump to see if my #7 injector would spray fuel into the port, to verify a suspected bad injector. I turned the key on, and nothing came out of the injector. But fuel came pouring out of the pressure regulator vacuum hose that goes to the upper intake manifold. So I've had a cracked diaphragm in the fuel pressure regulator all along causing this problem, pumping fuel into the intake manifold. Since #7 cylinder is at the rear of the engine, that's where it went. The Ramjet manifold has a raised area in the floor that separates the #7 from the #8 port, that's why it didn't go to #8. It also explains how I got ~4 quarts of fuel in the oilpan which didn't seem possible with just a leaky injector.

I also found small bits of rubber in the regulator screen, probably from when the front fuel line blew out. I have a fuel filter in the rear that should have prevented anything getting past it.

So my injectors are probably fine . I checked them with an ohmmeter and they all measure the same. I also checked for shorts in the harness and found nothing. Also, if the problem was electrical I would have had the same issue in #5 cylinder.

I bought new Holley injectors so I guess I'll use them anyhow. Now I have to get a new regulator.

[WagonCrazy]

so it's back to the fuel desolving the rubber parts in your fuel system? Begs the question: What other rubber parts are in your fuel system that aren't up to snuff with todays fuel? I'm sure this is not a surprise to you, given the earlier issues with the rubber hoses back by your fuel tank.

[chevynut]

so it's back to the fuel desolving the rubber parts in your fuel system? Begs the question: What other rubber parts are in your fuel system that aren't up to snuff with todays fuel? I'm sure this is not a surprise to you, given the earlier issues with the rubber hoses back by your fuel tank.

I don't think that had anything to do with the fuel pressure regulator going out.

The rubber that disintegrated in the tank was a couple years ago and I drained all the fuel out. Anything left should have gotten filtered out by the filter at the rear of the car. The rubber hose that ruptured outside the tank is the same situation. Everything should have gotten trapped by the filter. I now have submersible hose on the pump, and the external hoses are now PTFE which I should have done from the start.

The only way rubber could have gotten to the pressure regulator screen was from the front fuel hoses deteriorating. Now those are also PTFE. So there should be no rubber in the fuel system now except the 0-rings on the injectors, fuel pressure regulator o-rings, and AN adapter o-rings for the fuel lines. I was surprised at how big the pieces were in the pressure regulator screen. I plan to flush the lines again before putting the new regulator in.

Getting the correct regulator is a mess. GM lists two regulators for the Ramjet 502. Early ones used a 43PSI regulator, and later ones used a 60PSI regulator and the parts lists for the Ramjet 502 list different parts. The part I had was for the newer Ramjet 502 and is the same regulator and fuel rail used on 1996-2003 Vortec 454 and 496 engines. However, most sites claim the later injector is only 36 PSI which can't be right. You can't even get corect info from AC Delco or Delphi on the pressure rating for different part numbers. Some guys on the truck forums used the 217-3073 regulator specified for their 454/496 trucks and said it outputs 58 PSI. Delco even says it's 36 PSI. If it's wrong it's going back.

Since the new ECU fires all the fuel at one time for each cylinder, I want to use the higher pressure regulator since more fuel is required per pulse. When batch-fired in pairs, each injector fires twice per two revolutions instead of once.

This is really blowing up on me. If I would have checked that vacuum line all I would have done is replaced the pressure regulator and been done with it. Since I thought the problem had to be the injectors, I bought the new Holley injector set. $485 list price. Then I had to take the intake off, $30 gaskets. Then I decided to upgrade the ECU...$654 plus $333 for the harness, plus ~$100 for connectors. Then I decided to go with the dual sync distributor to get timed sequential injection....$414. I just found out that the ECU doesn't have a coil driver for a single coil in it, and the distributor doesn't have a coil driver. So there's another $306 for an MSD CDI box. Then $65 for a new fuel pressure regulator which was the original problem. Now I'm hoping I don't have to change my coil or something else.

It's strange....the ECU can drive 8 individual coils without an ignition box. But to drive a single coil for 8 cylinders they require a CDI box. Why would they design an ECU like that?

So $2387 and several days of work later I am back to where I was, although with a better ECU.