This should be a simple fix however, I must be pretty simple because I can't seem to find the solution. This has happened several times now including once that blistered the paint where the gas ran out.I d
Underneath my '36 chevy sedan is a poly gas tank...I don't fill it up completely...it is vented with a hose and screened vent cap that is not plugged or at least I can blow air in and out of the hose easily. When I do that I'm blowing air into air at the top of the tank, not into gas. I've changed gas caps and put a new push button type to release and pressure before opening. Here's the problem: gas pressure builds in the tank and spews out the vent as well as the gas cap even after the car has been parked in the garage for several days garage door closed or open, it doesn't seem to matter about the air temp or sunlight that actually never gets near the tank. Do the poly tanks expand and contract that much? I installed a drain tube where the push button on the gas cap used to be hoping that will prevent gas from dribbling down the side to the car....Any thoughts or suggestions would be most appreciated.