After driving around for a while and parking the car i went back in the garage and heard a very faint high frequency sound thats not very loud. Any higher and I wouldn't be able to hear it. Its comeing from around the gas tank area. If I take off the gas cap, the sound will go away. It doesn't do this on my other firebird but my cars are quite different compared to each other. This is on my 86.

 

Maybe you are getting excessive pressure in the gas tank, and the noise that you hear is the pressure escaping. When you remove the gas cap, you are letting the pressure fully release. Try swapping your gas caps from the other car and see what it does.

 

I'll try that. On either car I hear a whoosh of air when I take off the gas cap. They are both fuel injected.

 

The gas tank is supposed to be pressurized. That's its job.

Sounds to me like the little relief valve thing (plastic piece on the end of a fuel line just inboard and in front of the left rear tire) is broken.

 

I thought that it depended on what year the car was. I could have sworn that some cars came with vented gas caps to keep pressure out of the tank altogether. But I could be wrong, and if I am then you'll just have to

 

It probably is. What happens if the part is bad? Will the car run any differently?

 

Yes in fact that IS wrong. None of these cars had vented gas caps.

US cars anyway, have all had pressurized systems for many years now. Since the late 70s sometime.

In fact, where I live, the gas cap is THE ONLY actual "emissions" device they physically inspect to see if it works; they put it on a tester to see if it holds pressure.

No the valve being broken won't really affect how the car "runs".

 

The good ol' flatulation valve...

 

Ok, looks like I was wrong then. But you didn't even me, what gives!

 

Well, OK then....



I guess I'm getting soft or something, missing an opportunity to virtually smack somebody!!

 

actually, it's called an e-smack!