Over pressurized gas tank

[keepitrunning]

I have a 1983 fj60 and I had a rusted out gas tank so I used the por 15 to stop the rusting. After that, the gas tank would leak out of the filler cap and only when extremely hot. It got worse and worse and it would do it just when warm out and so I replaced the charcoal canister. That did not fix the problem. Does anyone know if there is a valve or anything that can be replaced to fix this or am I just missing something with it. Any help would be appreciated.

 

[Randy88FJ62]

Did you buy a used or new charcoal canister? If everything is routed correctly you should not be having an issue.

If the canister is not new then my guess is it is also bad. A Simple test is to swap the two hoses on the top of the canister and see if that gets rid of the over pressurization.

Some here buy vented caps to avoid fixing their gas system.

 

[BlackCat]

There is a one way valve in the charcoal canister which gets frozen/seized, allowing pressure to build. Swapping the two lines that go into the top of it is a common remedy.

 

[Randy88FJ62]

See post #10 for a view of the check valve. I rebuilt mine in about 2 hrs.

Charcoal Canister Rebuild - going for it

 

[John Staton]

I have an 83 and had the tank replaced via the recall. I had also had the truck desmogged so dont have a charcoal canister. I was getting a lot of pressure build up in the tank that was very noticeable when I would remove the cap to fill up. I got some recommendations in the thread below and the easiest solution for me was to just drill a very small hole in the gas cap.

Pressure build up in gas tank

So when I go to refill my tank there is a lot of pressure that is released when I loosen the cap. I guess I had gotten kind of used to it, but it really worried my son the other day at the gas station. I have read a few threads on this and I see the charcoal canister being referred to, but mine...

forum.ih8mud.com

 

[Randy88FJ62]

what happens when you roll it on it's side? Not the best solution in the world.

 

[OSS]

If a small hole is drilled in the cap (not recommended- I tried it) the tank can siphon liquid gasoline through the vapor lines if the tank is filled to the top. Gasoline can then flood the charcoal canister and literally come gushing out of the bottom of it at an alarming rate. Once the charcoal canister gets fully saturated with liquid gasoline, the EVAP system will suck it in and the engine will choke on it when the gas pedal is pressed down. You won't be able to drive the car.

 

[mattressking]

Perform the test below on one or both of your charcoal canisters. If this does NOT work (usually doesn't at this point) I successfully dribbled carb cleaner into the Tank Pipe and cycled with a mixture of compressed air and vacuum pump. After a few attempts, the check valve freed and I had a functioning charcoal canister that would pass smog and no gas smell.

 

[Ian Crawford]

If a small hole is drilled in the cap (not recommended- I tried it) the tank can siphon liquid gasoline through the vapor lines if the tank is filled to the top. Gasoline can then flood the charcoal canister and literally come gushing out of the bottom of it at an alarming rate. Once the charcoal canister gets fully saturated with liquid gasoline, the EVAP system will suck it in and the engine will choke on it when the gas pedal is pressed down. You won't be able to drive the car.

Interesting! I have a vented gas cap, same concept as a small hole and have never had an issue! Definitely one to keep an eye on, worth buying a non-vented cap?

 

[Spike Strip]

Did you by chance plug the Vapor Vent Holes when you sloshed POR15 around in the tank ?

 

[tmxmotorsports]

Did you by chance plug the Vapor Vent Holes when you sloshed POR15 around in the tank ?

Exactly what i was going to say i have por15 the fuel tank in the 84fj60 that i am working on this could be your problem.