I just put a new head gasket in a friends U42t mini. It has the 3g83 engine. At this point it is a no start. I think the fuel pump is bad. It runs with distributor when cranking, but acts like it does not have enough power to suck the fuel out of the tank. Is there a check valve or anything that is supposed to stop fuel from back flowing into the tank? I then took the inlet line off the carb and ran a separate line from a funnel to it. I can pour fuel in it and crank engine but nothing happens. The fuel also will run out of the funnel after a few minutes through the return outlet on the carb. I’m assuming the pump keeps a constant flow normally. I’ve pulled plugs and I don’t think I’m getting fuel into the combustion chambers. Any ideas? Truck supposedly ran before head gasket went out. And I do have 150psi compression.