Gas cap

[ABDULLAH D AFGHAN]

real easy one here guys. Whenever I open my gas cap the pressure buildup is huge, so I assumed that my gas cap was bad so I got a STANT gas cap for my car from Oreilly's and i smelled gasoline so I put the original old cap back on and I dont smell gasoline but just alot of pressure when i open the cap. Is that pressure bad or good? Is it normal for it to have so much pressure inside when you open the gas cap?

 

[a.Lpha]

this is an old thread, but now that i read it, i hope it's normal because mine does the same thing.

 

[a.Lpha]

this is an old thread, but now that i read it, i hope it's normal because mine does the same thing.

 

[ABDULLAH D AFGHAN]

Mine is a 93 LS. what do you have?

 

[ABDULLAH D AFGHAN]

Mine is a 93 LS. what do you have?

 

[a.Lpha]

94, I do think it's normal, but would like to be sure

 

[a.Lpha]

94, I do think it's normal, but would like to be sure

 

[Peewee]

All cars will do it when the tank is low.
The lower the tank, the louder/longer it will do it.

I'm sure the weather(temp) plays a big part too.

 

[a.Lpha]

Do you know why it does it? I've never seen this on any car or boat i've driven before.

 

[ABDULLAH D AFGHAN]

My beat up honda with over 200k miles doesnt do it. I m wondering if that seal around the cap has gotten old and needs to be replaced. A.lpha have you replaced ur cap?

 

[a.Lpha]

nope never been changed, everything on the car is what came with it, say for now the alternator (and tires et al. but that is a given)

 

[Peewee]

I *think* its due to the way the charcoal canister works.
It may only work when the pressure in the tank is above atmospheric pressure and not below.