iirc, gas caps are supposed to allow air into the gas tank, but not out of the gas tank.

i dont think that air is getting into my gas tank when the cap is on... when i remove my gas cap, there is a sudden surge of air going into the tank. it sounds like opening a soda bottle that was just shaken up.

do you guys think i should get my gas cap replaced? would this low pressure in the gas tank affect my fuel system at all?