fuel pressure in my gas tank

[project92camry]

every time i open my gas tank theirs fuel vapor pressure in there. i kno theres sumthing wrong with my evap system but not sure where to start looking. what can cause pressure to build in my tank.
o and the gas cap is new.

[Hajoca]

Describe sound of pressure release, the hiss may be air sucked into tank.

[felpz123]

i thought it was supposed to do this?

[project92camry]

its just pressure build up in the tank. i can feel it when i take off the cap cause it feels like the pressure is pushing the cap off when i finish unscrewing the cap. ill see if i can video tape it this week

[ghettosled]

pressure builds in my tank as well. i always hear a suction noise when i start to unscrew the cap. its always done this, more so on hot days.

[CupCate18]

Seriously? Wow.....






This is normal.... If it is sucking air into your tank, that would be trouble. Air blowing out is perfectly normal.

[whip_cracker]

Mine does something... not sure if it's sucking in air or letting air out. I'd imagine it'd be sucking it in, coz the fuel will go lower, but there's no air to replace the fuel being used? Unless there's some system that allows the air out... or yeh, something like that.

[Hajoca]

Sucking air in, reduces the VOC (unburned fuel) emissions. the engine's vaccuum does this, and also draws the fuel vapour out of the Evap canister.

When it is warm out, the Fumes are absorbed into the charcoal canister.

[CupCate18]

If your tank is sucking air in, it would get air in your fuel system, resulting in not starting, or being extremely hard to start.