big clunk noise after turn off.

Just a quick question. About 15 minutes after i shut off the engine and leave the truck, there is a large clunk sound that has enough force to shake the car slightly and set off the aftermarket alarm system. I sat in the car and waited and when it hit it was clearly noticeable. Im not sure what this is, but it definately doesnt sound good and im sick of my alarm goin off. Any help would be great. thanks :icon16:

Just a quick question. About 15 minutes after i shut off the engine and leave the truck, there is a large clunk sound that has enough force to shake the car slightly and set off the aftermarket alarm system. I sat in the car and waited and when it hit it was clearly noticeable. Im not sure what this is, but it definately doesnt sound good and im sick of my alarm goin off. Any help would be great. thanks :icon16:

Yep, it's your plastic gas tank. Watch it next time. I can't remember what to do about it though other than asking the dealer??? I think it has something to do with the fuel return line.

Ooooh, so that's what they mean when they say "you've got a clunker"...just kidding :). You may want to open your gas cap after shutting your engine off, to see if it sucks or blows air. Open the cap slowly though, because if it blows gas, you'll get a face full of it. I'm not sure if these trucks have vented caps or not. If it does, maybe yours isn't working correctly. Good Luck :).

Ooooh, so that's what they mean when they say "you've got a clunker"...just kidding :). You may want to open your gas cap after shutting your engine off, to see if it sucks or blows air. Open the cap slowly though, because if it blows gas, you'll get a face full of it. I'm not sure if these trucks have vented caps or not. If it does, maybe yours isn't working correctly. Good Luck :).
As far as I know, there are no vented caps made anymore. The tanks themselves are pressurized and then measured for leaks. If it detects a vapor leak, it will throw a code. That's why you can not fill the tank with the vehicle running anymore.

Well thanks for the replies but i am still oblivious about what that annoying clunk is. Please help.