Can a pressurized tank lead to a fuel delivery issue?

[RUSH55]

Hey @RUSH55 so went for a drive last night, still seems to have had some pressure and gurgling when i opened the fuel cap.

Albeit I don’t know if I was smelling the toxic fumes as much and it ran with no hiccups (still not sure if the pressure in the tank and misfires are related).

Either way im going to blow some low pressure into the 4 vent ports i see. Adding some more pics of the actual vent hoses from vapor separator to the tank itself.

Okay, that is interesting. There should be zero pressure in the tank, and there is still pressure in the tank. Haven’t yet heard of tank internal vent lines being plugged, but anything could happen. All the hoses appear to be in good shape.
Yeah, I’d blow air through each of those vent hoses (with the gas cap OFF) and be sure they are clear. Check that vapor separator can to be certain it’s clear (I’ve always thought they were empty, but don’t know for sure).
We’re trying to isolate a cause of obstruction, and then move forward from there.

 

[Ol Yeller]

Check that vapor separator can to be certain it’s clear (I’ve always thought they were empty, but don’t know for sure).

Yeah, earlier post said had been overfilled so possibly fluid in there preventing the vent

Not sure why but the venting on older vehicles van sure cause headaches, my old 510 wagon had lots of issues too.

 

[Pighead]

Yeah, I’d blow air through each of those vent hoses (with the gas cap OFF) and be sure they are clear.

Do that with as little gas in the tank as you can manage, expect a spew anyway

 

[effjay55]

So I just blew into all 4 gas vent hoses and felt air coming out of the inlet. So I’m guessing theres no clogs, the fuel vapor separator also doesn't seem to have any obstruction , blew into all ports and felt air coming out, no fuel was in it.



(Now i get why this emoji exists)

Edit:

Also adding video that shows all clear from back fuel vapor separator to the charcoal canister

 

[55guy]

We have the same problem , Keep us updated ,Thanks

 

[RUSH55]

So I just blew into all 4 gas vent hoses and felt air coming out of the inlet. So I’m guessing theres no clogs, the fuel vapor separator also doesn't seem to have any obstruction , blew into all ports and felt air coming out, no fuel was in it.



(Now i get why this emoji exists)

Edit:

Also adding video that shows all clear from back fuel vapor separator to the charcoal canister

Yeah, kind of at a loss as to how there could be either pressure or vacuum in the tank when the vents are wide open.

From the video it almost sounds like the vents you’re blowing into are submerged. There shouldn’t be any gurgling when blowing air into the tank from a vent line.

 

[bobm]

1 word ETHANOL ****s everthing up. is for eating not for ****ing fuel.

 

[bobm]

Check ya Hole

 

[RUSH55]

The air is going through the lines and coming out on the ceiling of the tank, which should be an airspace, unless for some reason they’ve all broke loose and are hanging in the fuel!

 

[effjay55]

The air is going through the lines and coming out on the ceiling of the tank, which should be an airspace, unless for some reason they’ve all broke loose and are hanging in the fuel!

View attachment 3824634

Well just took it for another test drive and guess what??!? No pressure or wooshing.

Maybe blowing into the lines with the compressor pushed out some fuel that was stuck in there after it was overfilled? The overfill happened awhile ago though…Idk just a theory.
Interesting what you said about the gurgling @RUSH55 … Im going to try to blow more air in it to see if it continues to make that sound. The tank is now sitting at half according to the fuel gauge.

Going to plug in the check valve line again and see if all is nominal.

Ill let yall know if the tank builds up pressure again

@bobm I know ethanol f***s everything up, I use an ethanol treatment to try and help mitigate that, and run 91 octane since its supposed to have less ethanol.

Now i gotta figure out why the engine misfired during the test drive. After I remade the fuel lines I thought I had fixed the issue, Im thinking maybe I should run one of those clear universal fuel filters in a few spots to see if its just debris or something. Might need to rebuild the hard fuel lines that run along the undercarriage too now that I think about it.

 

[RUSH55]

You’re going to need to change the fuel filter pretty frequently for the foreseeable future.

 

[PabloCruise]

Well just took it for another test drive and guess what??!? No pressure or wooshing.

Maybe blowing into the lines with the compressor pushed out some fuel that was stuck in there after it was overfilled? The overfill happened awhile ago though…Idk just a theory.
Interesting what you said about the gurgling @RUSH55 … Im going to try to blow more air in it to see if it continues to make that sound. The tank is now sitting at half according to the fuel gauge.

Going to plug in the check valve line again and see if all is nominal.

Ill let yall know if the tank builds up pressure again

@bobm I know ethanol f***s everything up, I use an ethanol treatment to try and help mitigate that, and run 91 octane since its supposed to have less ethanol.

Now i gotta figure out why the engine misfired during the test drive. After I remade the fuel lines I thought I had fixed the issue, Im thinking maybe I should run one of those clear universal fuel filters in a few spots to see if its just debris or something. Might need to rebuild the hard fuel lines that run along the undercarriage too now that I think about it.

Good stuff in here!
Nice work @RUSH55 posting the picture showing where the vent lines live.
With the tank half full now those vent lines should not be gurgling at all.
To remove any doubt - You have run air back through the lines into the tank, and up to the charcoal can, yes?
Have you also run air through the vapor separator itself? Through the check valve?
Good luck!

 

[effjay55]

Good stuff in here!
Nice work @RUSH55 posting the picture showing where the vent lines live.
With the tank half full now those vent lines should not be gurgling at all.
To remove any doubt - You have run air back through the lines into the tank, and up to the charcoal can, yes?
Have you also run air through the vapor separator itself? Through the check valve?
Good luck!

Thank you @PabloCruise

No matter how many times I blew into the vent lines I could hear gurgling, I could also see fuel coming up the filler line too (not overflowing but slowly rising the more air I pushed in). I was blowing air at about 10-15 psi and would hear gurgling, but when blew with my mouth it wouldn’t really gurgle and there didnt seem to be any back pressure.

I did in fact blow air towards charcoal canister and it was all clear (posted a short video clip of it). I also blew air into all inlets of the separator and the outlet, all seemed clear and free flowing.

I am almost thinking that maybe I am blowing air at too high a pressure and its causing just enough pressure inside the tank that it displaces the fuel a little bit and causes it to rise + gurgle? I am not too sure… I had to leave again for the weekend but Ill be doing more testing this coming weekend.

I put in a new clear universal fuel filter on both in and out gas lines to see if there are any other variables, like debris, causing the misfires but I am guessing its this weird pressure thats causing them.

I will be taking it for a test drive this weekend to see and will report back.

 

[RUSH55]

You might try putting the cap on, and putting a small amount of air through one of the vent lines and see if you can feel air coming back out the other vent lines. Regulate it to only 2 - 3 psi if you can. 10 - 15 psi is too much IMO. No telling what’s going on in there with that much pressure.

 

[bobm]

Someone in thar

 

[effjay55]

Someone in thar

you have a valid point Bob ... I didn't think of the ol' poop in the tank , this is L.A. after all...

 

[effjay55]

You might try putting the cap on, and putting a small amount of air through one of the vent lines and see if you can feel air coming back out the other vent lines. Regulate it to only 2 - 3 psi if you can. 10 - 15 psi is too much IMO. No telling what’s going on in there with that much pressure.

That's a good idea I'll try that this weekend. Thanks

 

[PabloCruise]

Someone in thar

The old "Upper Decker"?

 

[bobm]

Me going through same it driving me ****ing Crazy

 

[RUSH55]

What’s been determined here?