I posted a response to another thread but I never got an answer......when my car is off and there is NO key in the ignition my car will "moo" as my friends call it.......every 20 minutes or so.....i've isolated it to the rear of the car which leads me to the fuel pump......it doesn't sound bad or anything while the car is running.......to me it just seems like it keeps priming itself to keep fuel pressure like when you first turn the car on.......

 

The fuel pump doesn't "prime" unless the ignition is on.

More likely it's the pressure relief valve.

 

well like I said it does this every 20 minutes or so.....I've never timed how long it does it but I've heard it go off at least 3 times........

 

Yup; pressure relief valve.

Sounds kind of like something blowing its nose. It'll do it for a second or 2 every few minutes after parking the car on a hot day after getting it good and hot, for maybe a half hour or more. Right?

The valve looks like a UFO, is on the end of a steel line hanging down just inboard of the left rear wheel in front of the rear end. AFAIK they are only available from GM. Seems like last time I bought one it was like $25.

 

yeh sofa king your exactly right.......I usually drive my car alot during the day....

THANKS!