neurocity

iTrader: (17)

So I left my SC outside last night. This morning weatherman's calling for rain. And not wanting to re-wax for the 400th time this year, I pull it into the garage. About an hour later, I go out to the garage and hear this air leaking sound. Thinking I now have a nail in my tire I run around the car checking the tires. Then I hear the sound coming from the gas-flap. Open it up and its coming for the cap. So I undo the cap. A rush of gas smelling air flies out, Kinda like when you let your gas tank run low and open it for a fill up.
But I have 3/4 of a tank?

Is my gas cap bad? Is this normal? Is it because the car was started and run for a whole 3min this morning?

Never had it happen, or noticed it before.
Anyway any ideas or direction would be great?

Matthew...patron saint of sarcasm

stokdd

Don't know the answer to your question, but I do have a similar 'issue'.

Every single time I fill my SC400 with gasoline there's mad vacuum (or pressure?) in the tank - mucho air rushing when I undo the gas cap. I know it's normal when the tank is near empty, but this happens even if I have half a tank or more! I've never nad a car develop so much vacuum...is this normal?

poser714

my car does it all the time. i think its normal..

jgdynamics

iTrader: (16)

umm, i got that on my mr2, then i connected my charcoal canister back on... and the pressure stopped building up... not sure how this works on an sc though

hope that helps... its parts of the emmisions stuff... evap i think

0l33l

iTrader: (3)

Check if the gas cap is ok. I bought my car with a bad gas cap and it wouldn't release the pressure to the outside. Bad seal I guess.

cloudnine

My SC400 which is completely stock and my SC300 with twin Walbros, and no EGR, PCV, or charcoal can, both hiss when the gas filler cap is loosened. I think it's completely normal.

BiZ

They all hiss when you loosen them. But hissing after you pulled it in the garage without loosening the cap is not normal. I would think the car seal is bad.

neurocity

iTrader: (17)

after looking at the gas cap it says "turn till you hear clicks" I never turn it that tight.

np20412

Haha that may be your problem.

If you aren't tightening it enough, it will hiss as the vacuum is not sealed completely. I put the cap on and turn it hard. It doesn't matter how much it clicks, just that it DOES click.

I always just put the cap in and twist that sucker fast as i can until it starts clicking to like 4 or 5 clicks.

neurocity

iTrader: (17)

Yea....later I'm going to turn my head till it "clicks" 4-5 times.

Tammy

If the cap was not tight, the vacuum reservoir, that is used to suck the fumes into the charcoal canister, leaks to the atmosphere.
(OBD II vehicles would sense this and create a check engine error.)

The when the engine is running, the manifold vacuum pulls the fumes from the charcoal and is burned as normal combustion.

A snug fit should be all that is required to seal the O-ring on the fuel cap. I use a little Aerospace 303 on this seal for lubrication.

neurocity

iTrader: (17)

I'll just run on down to NAPA and get some of that.

Tammy

Ace hardware is a national supplier ...