parked car, again it wouldn't start

I fitted the new fuel pump and my car started again but after driving a few kilometers I parked my car when I wanted to drive again it wouldn't start. I jump start my car but reverse the cables so when I try to start the car it wouldn't cause I didn't get fuel at my injectors I check my fuses plug out the wires of the fuel pump to check if there is power on the cables and there was so I fitted a new fuel pump and then the car started again but after a few kilometers I parked the car but when I try to start, it did but just died again so when I checked I couldn't here my fuel pump comes on but there is power on the switch of the pump. When I put the pump direct on the battery it pumps perfectly even if its taken out of the tank still connected to its original wires.