both of mine do it . i think its normal .

 

Mark,

Thanks for the response. I don't remember my old 1969 doing that at any point from 1989-1994 when I owned it. Of course I was a kid then. Who knows maybe I'm pickier now as I am much older. But I still don't remember that sound coming out of the tank. The fuel pressure when running seems normal on the fuel PSI gauge.

 

Sounds like the vent side of your cap is plugged. I would think that on a single line system, you have to have some type of vacumn/pressure vent. I say vacumn as fuel level lowers, it should be displaced with air. You also have the vapor expansion factor too.
When I added my electric pump, upon filling , I noticed a suction swhoosh,when removing cap, which told me my pump was pushing fuel down line and I had no pressure balance. I got the GM cap that was stamped, Antisurge/vented. No more issues.

 

I have always gotten the "whoosh" after my Camaro has been sitting for a while. During the winter I typically leave the tank mostly full with stabalizer. In the spring I'll open up the cap and hear the whoosh. There have been times when first running that if I don't open the cap to vent the engine will starve for fuel. Venting the cap has always fixed that problem. Again this only happens after the car has been sitting for quite a while (months).
ColoradoZ28

 

Both mine do it. Seems the hotter the day the more the woosh. I'm guessing the "venting" is constant but the pressure can still build up beyond the caps ability to vent it all out.

 

South Side Hitmen - I recall buying a dragrace video from Autozone about 7 years ago that had a group of people from Chicago called the Hitmen as one of the featured stories. Was that you? If so - very cool. Well I used to live out there and sure do miss the Pizza (but not the winters). Anyway - good job on da Bears making it to the Superbowl. Now if they could only get a QB - need to get rid of Rex Grossman ASAP.

p.s. my gas cap whooshes a little too - more so on a hot day.

 

I think the S.S. Hitzmen were 16' Softballers. Anyway,
Mine does it with a new stainless tank & new cap.
Mike