open gas cap and a whooshing noise is heard

[tanman2003]

so im guessing that there is a vacumme or too much gas vapor pressure built up in there.

either way im thinking its the charcoal canister, or one of the lines to it, is clogged.

anyone know why it would be bad or what would happen if i diddnt fix the problem?

maybe i could just ignore it?

[BigMike]

This is perfectly normal. The fuel system is designed for the engine to suck vapors out of the tank so that when you open your gas cap there are none. On newer trucks there is a solenoid that will delay about 30mins before allowing fresh atmospheric pressure to vent back into the tank.

BigMike

[tanman2003]

sweet thanks

[Brandon]

how low was your gas?

[BLACKDOG]

mine always does that, and I usually fill up between a quarter full and E

[tanman2003]

usually empty, but i think it does it all the time no matter what the level.

[mudaddict]

mine does that usually on really low gas! i dont know the only times i fill up is 1/4 a tank or lower

[guywithuglyyota]

never had a car that didnt do it.

[Makohon]

same here... newer older... they have done the same with me.... volvo... wrx... newer yoda... same thing