GAS TANK FILLER NECK, BACK-FLOW

[Dave the Wave]

put a so-called "back flo preventer" in my `57 filler neck,does not work, period.

[WagonCrazy]

yeah, I'm having the same issue with my setup too. Hard left handers seem to leave the residual smell of fuel. I'm sure it's getting past that preventer, and ejecting out the filler neck. :(

[Dave the Wave]

i mean i can not fill the tank, anyway, anyhow, without it splashing out. ordering a new "o" ring and yanking it out. ordering an "o" ring, just to be sure.

[Belair-o]

Hi Dave,
When you say it doesn't work, you mean fuel still sloshes out of the fuel tank filler neck under acceleration?
Regards, Doug

[WagonCrazy]

When you say it doesn't work, you mean fuel still sloshes out of the fuel tank filler neck under acceleration?

Doug's asking a legit question here.

In my Nomad, I have no problem filling the tank without it splashing back. But when driving it, and cornering hard left with anything more than a half tank of fuel...it comes out past that backflow flap setup and leaks out the filler neck by the cap.

Its not quarts of fuel leaking. Just enough getting by to smell when it comes all the way out.

I suspect the design of this filler backflow preventer could use some improvement. Meaning, it's not "fuel tight" in its design. Its just a gravity balanced, oval shaped flap of steel inside. It's definately not resting against any kind of seal in the closed position.

[Dave the Wave]

i have no idea about acceleration, i`m not behind the vehicle, nyuk,nyuk, nyuk! but when filling it,,,,,,, all over the place. and i know it`s a legit question. and i tried different ways of filling it, for example, the noxell is`nt in to far, to hold it open. thanx.

[Belair-o]

Doug's asking a legit question here.

In my Nomad, I have no problem filling the tank without it splashing back. But when driving it, and cornering hard left with anything more than a half tank of fuel...it comes out past that backflow flap setup and leaks out the filler neck by the cap.

Its not quarts of fuel leaking. Just enough getting by to smell when it comes all the way out.

I suspect the design of this filler backflow preventer could use some improvement. Meaning, it's not "fuel tight" in its design. Its just a gravity balanced, oval shaped flap of steel inside. It's definately not resting against any kind of seal in the closed position.


Hey WagonCrazy,
Well that is a bummer, since that is exactly what the backflow flap is supposed to cure. Drat.
Thanks, Doug

[BamaNomad]

Even if there was an 'absolute' stop valve in the filler neck, when the tanks are FILLED, there would likely be fumes and a little gasoline coming thru the vent hose...

[Dave the Wave]

even when filling the tank, slow, it splashes out.

[WagonCrazy]

Dave, are you 100% sure you have that installed that in the correct orientation? (and not backwards?). I have no issue filling my tank at the pump with mine.

[WagonCrazy]

there would likely be fumes and a little gasoline coming thru the vent hose...

That situation can exist for sure. There's no backflow valve in my vent tubing... and it does connect at the "top" near the filler tube connection point.

[BamaNomad]

The filler tube on a stock tank (sedan or wagon) is not IN the top of the tank, but instead comes into the tank at the top of the SIDE of the tank, so if you fill your tank absolutely FULL, the filler tube will have several inches of fuel in it as well, and of course the filler tube is not exactly vertical either...

[Dave the Wave]

the new O ring is in thev mail, just ordered it in case i moved it around, so, anyway, we`ll see, but i doubt it. let ya know. thanx

[Dave the Wave]

well, i finally took this apart. "wagon crazy, it wasn`t in backwards. IT WAS IN "UPSIDE DOWN"! ok, the flap itself, one side of the flap has a washer tacked to it, to keep it closed, acting as a "weight". having it in "upside down, it was staying open. [ass that i am] so we`ll see next time i fill it. ,,,,, ta-dah!

[WagonCrazy]

good news Dave. Now...the vent tubing may still be a culprit when running close to a full tank and cornering hard. I need to figure that one out on mine...

[Dave the Wave]

we`ll see when i fill it this week.

[Dave the Wave]

cant wait to fill it up.

[Dave the Wave]

tryed to fill it today. could`nt even get a quart in, splashes back.mi don`t get it.

[Dave the Wave]

ok, flipped it again. ok, now this thing can only go in, fit in, 4 different ways, period. tried all 4, out it came, period. f___ it!

[WagonCrazy]

Hmmm...something doesn't seem right here. Mine is installed at the base of the filler tube (and before it meets the tank tube). Its inside that short 4 inch piece of hose you see in the pic below. There are 3 clamps...one on each end connecting the hose to each filler pipe and the center clamp holds the flap assembly in position "inside" the hose.
I haven't had any issues with fuel coming back out during fill ups. It should work by gravity...the flap should stay in the shut position (tip of the flap that is nearest the tank facing "down") This would prevent fuel from "exiting backwards" out of the tank.
Hope this helps.

Here's a pic looking straight up from under the rear wheel well opening:

12009

[Dave the Wave]

yes, you are exactly right! i don`t get it! and, my lower tube goes directly into the tank, no other hose connection like yours. your car a wagon? thanx for the pic/response.

[Dave the Wave]

NOW HOLD IT!!! hold on right here! your hose with the "2" clamps, that is at the "cap" end? looking closer at your pic!

[Dave the Wave]

i gotta crawl under this thing again! i`ll be back shortly!,,,,,,,,,,,,,,,THANX AGAIN

[Dave the Wave]

ok, mine is not like your picture. my sedan only has the "hosE" piece in the downward tube, none in the veritcal section.

[WagonCrazy]

Mine is a nomad wagon, and the filler tube(s) are not stock. There's an extra sweep-90 in there coming off the upper tube. That way I could use a sedan tank, which has the tube exiting out the side of it.
And the short piece of rubber you see with all the hose clamps has the flapper valve slid down inside of it.

[WagonCrazy]

So I will mention here that I have no issue filling it up, but when the tank is completely full, the fuel level is up in the filler tube. And even though I have that flapper valve in there, there is still a seperate vent pipe that doesn't have any type of valve in it, and hard right hand turns mean I smell fuel shortly afterwards. So I'm suspecting it's coming thru the vent hose and still spilling out at the filler cap. Need to plug up the vent tube temporarily and then take it for a drive and see if that smell continues.

[Belair-o]

FWIW, here is a shot of the stock component fuel filler setup on my 57 HT, with the Ecklers back-flow prevention flapper installed in the rubber portion:
12027
Regards, Doug

[WagonCrazy]

You flapper valve is actually "higher" that the way mine is installed. and it appears to be in a more "vertical" orientation. So I'm not sure if it would close by gravity or not. Mine is in a more horizontal position (lower-closer to the tank), so it wants to stay closed when fuel sloshes "outward", but opens right up when fuel comes "in" (from a fillup).

But I also suspect the vent hose is not preventing fuel from sloshing back on hard cornering. That's a problem I still need to solve on my nomad. Because I smell fuel after a hard right hand corner, and see fuel drying on the chrome stoplight/blinker assembly.

[Dave the Wave]

belair-o, exactly, i don`t get it. i tried it actualy 4 times now. thanx though.