How is the rubber hose from the line to the sending unit? Hoses breakdown from the inside over time and will block flow. Are you sure the pump is good? I would remove the line from the outlet side of the pump and spin the engine. If you get no fuel there, remove the line from the inlet side and see if any fuel comes out. If fuel comes out the inlet side and not the outlet side when the engine spins, the pump is bad.
