Gas Tank Pressure

[LA1]

Hello,

Sorry if this topic has been covered before but I've been searching for 45 minutes and haven't come up with anything.

Our 92 LS 400 has a lot of pressure (enough that it hisses for ~30+ seconds and would blow the cap off if I spun it all the way loose) behind the gas cap when I remove it to fill up. Is this normal?

I've just noticed it because I've been driving this car due to the high gas prices, but my wife says it has been doing it for a long time.

Thanks,

Levi

[ED.]

I am pretty sure my aunts 93 SC does the same thing when you open the cap. Kind of annoying and the only car I have ever seen do that before.

I am not sure what causes it but will do some research on it.

[LA1]

If you find out any info that would be great. I've searched on the internets as well with no luck.

I don't mind little quirks, as long as it is safe.

[vyhanh]

Someone in the past mentioned that the rubber O-ring inside the gas cap needs replaced.

[eatingupblacktop]

There's always going to be some pressure in the tank due to heat from the exhaust and outside temps. But if it's excessive try replacing the gasket in the gas cap or the gas cap itself. They're not expensive.

http://www.lexls.com/tutorials/maintenance...lcapgasket.html

[LA1]

Thank you, your help is appreciated.

Now I will have to run down to the Toyota dealer and see if they have one.

[chilkoot]

how does that work? if the o-ring in the gas cap fails and needs to be replaced how would there be increased pressure in the tank? logic would say that a bad gas cap seal would be indicated by a lack of pressure. Do they "fail" when they flatten out and begin to seal too well?

[ED.]

how does that work? if the o-ring in the gas cap fails and needs to be replaced how would there be increased pressure in the tank? logic would say that a bad gas cap seal would be indicated by a lack of pressure. Do they "fail" when they flatten out and begin to seal too well?

I think the same thing too. I would of figured it was the little door that goes into the tank and not the cap itsself since it is only covering the wee flap/door thing. I would love to get any more info on this?