Gas Tank Pressure
 

Hey Guys..,
When I take cap off of my gas tank it always has pressure built up in tank..
Is that normal ?? When I try to blow air from canister back to tank it won't go...Is there a check valve in that line or is it plugged?? The PO said he put a new fuel pump in it and had the bed off to do that...Could the line be pinched??
It runs and starts great but the tank pressure doesn't seem right to me...
Thanks for the help,,,Dave