Thread: Gas Tank Overpressurized, Fuel coming out of Filler Cap

Jen, Interesting problem. If you added a vent then I don't see how the pressure can build up. The Swift and the Legacy release a fair bit of pressure when removing the filler cap. Does this happen with a full tank? is it better with half a tank? I see in the for sale a tank with some sort of breather valve ....did you change this? I don't have any issues with the gas tank pressure.

on this related note, I must have blown the seal holding the pump upper piece to the body of the gas tank because when I filled it the other day it was pouring out the top. and there was zero woosh when I opened the cap... damn these cars sometimes

No.. I just ran the car up the freeway during the heat of the day with less than 1/4 tank in it and gas still seeped out of the filler cap. The exhaust is also non-stock.. Larger diameter. possibly it is heating up the gas tank?

I don't think the check valve is facing the right way. Really make sure it's facing the right direction. If the charcoal caninster were full of gas, somehow....

Thank you for your input. The check valve is facing the correct way and all fuel lines and vacuum lines are routed correctly. I wish I could say it was something simple. Please keep the suggestions coming. Maybe there is something I have forgotten!!

Jen, So where is the fuel coming out of? the cap itself or that area? Having 1/4 of a tank is not enough to shoot the fuel out the filler cap unless you are pulling 10 g's around a corner...hahaha. On the top of the tank is the pump/sender plate which has in the middle has an breather pipe that goes to the filler cap area. Is it possible the fuel is going up this pipe? Me being a lazy bugger I ...

Is there an exhaust leak close to the fuel tank? I had same problem with a bobcat the muffler was missing an most of the heat stated in eng. compartment and gas tank was right above it and gas sounded like it was boiling. To me that sounds like your problem. I would drive it you figure it out.

SORRY. I mean i would not drive it til i figured out problem.

Jen, For sure your problem is heat related. I had the exact same problem due the exhaust getting hot. The fuel was getting hot and shot out the filler when I opened it. I'm thinking of going to a fuel cell.

lol, the terrible Toad metro did that the first week I was driving it after engine rebuild- It barfed a 6 foot geyser of gas on some wetback.... I never did figure out why it dad that, nor has it repeated though. It had about 1/3 tank....