I just bought a new tank with a competition engineering rear weld on sump with 1/2npt fittings that i had welded on. I have a BG220hr fuel pump system with a bg5000 fuel filter. The system is setup with a return also. When driving I constantly end up sucking air through the fuel pump and the only way to get it to suck gas again is to remove the fuel supply line at the carb, blow into it until I hear bubbles in the tank, turn the fuel pump on for a second with the line disconnected, then screw it back onto the rest of the fuel system. I have a return setup on the system that returns fuel right next the supply...could that have something to do with it? Its frustrating after i bought the new tank and sump as a way to solve all my fuel problems, but only to have more problems after I got it installed.