My tank is sumped, and apparently when everything was closed off of the stock sender, a valve was closed up or something because my tank becomes very pressurized and actually makes the tank cave in a little. When I take the gas cap off you can hear it snap back into place. Does anyone know whare I can get a vented gascap?

 

mine does the same thing....More then likely it was designed to do this. You may have problems if you change it....I'm not sure though.

 

i cant really here mine pop out.....but i have a out of tank trex fuel pump and i do not know how it was sealed up, but mine has extreme pressure as well, like huge gust for about 30 sec after i loosen cap...weird