Gas tank pops



I have a 2000 GMC Denali. The gas tank pops almost every time I turn it off. It takes just a couple seconds before it pops. It seems to pop louder in cold weather than in warm. Is this dangerous? What can happen if it isn’t fixed? I can’t tell which way the pressure is going. Appreciate any help!


Before you turn off the engine, remove the gas cap and see which way the air moves- in or out of the tank.


I have the same problem with my 2000 Blazer. It would make the popping noise 30 to 60 seconds after the motor was shut off. I replaced the gas cap, it made no difference. My mechanic checked it out and seemed to think it was coming from the exhaust system (heat shield?) and not to worry about it. The truck has been quiet since the spring, I guess it’s a cold weather thing. Anyway, the popping has been going on for over a year with no ill effects. If you take your gas cap off with the engine running, make sure to put it back on or you will get a Check Engine Light (CEL).

Ed B.