Excessive pressure in gas tank? - Toyota Nation Forum : Toyota Car and Truck Forums

speedyts49 · 08-26-2005, 09:55 PM

Excessive pressure in gas tank?
I released the gas cap on the Celica at the station the other day and it let off a whoosh like I have never seen in all my years. I was not doing any altitude change driving , just city stuff.
I am wondering if something is clogged that would cause this. Is there a vent that could be clogged.

The car runs ok other than hard starting when warm, an occasional EL code 71 coming on, a bit of a jerk when decelerating, and not the best gas mileage in the world(20 city).

I have changed so many egr related parts on this car, cleaned the injectors(witchhunter.com) changed fluids, filters, and just about everything else I could get to.

I guess I want this older car with 150k on it to run perfect.

So could it be clogged and where?

Rick89GTS · 08-27-2005, 02:55 AM

Doesn't a vented gas cap release that pressure?

***RningOnFumes*** · 08-27-2005, 02:59 AM

ya know we've been getting higher temps lately....wouldn't that cause more pressure to build?

flex-appeal · 08-27-2005, 08:10 AM

i thought the tank cap was sealed and pressure was vented under the charcoal canister. but im not really sure either

ST185 · 08-27-2005, 09:21 AM

The check valve in the cap allow fresh air in, to prevent vacuum in the tank. The valve on the charcoal canister and TVV (thermal vacuum valve) or BVSV (bimetal vacuum switching valve) on later model release positive pressure from the tank. Check that if it is clogged. The TVV (and BVSV) is on water neck.
Also, under the charcoal canister, there is another check valve that release air from the canister. Check that too.

Rick89GTS · 08-27-2005, 10:25 AM

^Ahhh, thanks for clearing that up Gary, I wasn't quite sure.

speedyts49 · 08-28-2005, 08:45 PM

Quote:

Originally Posted by ST185

The check valve in the cap allow fresh air in, to prevent vacuum in the tank. The valve on the charcoal canister and TVV (thermal vacuum valve) or BVSV (bimetal vacuum switching valve) on later model release positive pressure from the tank. Check that if it is clogged. The TVV (and BVSV) is on water neck.
Also, under the charcoal canister, there is another check valve that release air from the canister. Check that too.

The BVSV is new and is probably ok so that leaves the check valve. The check valve is not on the 91 though. There is a jet(m/t only which I have) so I suppose that could be looked into.
I can't find anything called a thermo vacuum valve but I take it that I either have that or a BSVS which I do have.
Then again it could be the heat.