when the pump is activated it pumps fuel through the line. When the car is shut off the fuel will return to the tank because the pressure is relieved. My pump was fine when I put it in. The problem might be in the wiring of the pump, fuel regulator, fuel filter, or mabey one of you lines in kinked. You can always test the leads in the rear of the trunk to see how many volts are going to the pump. Might want to do the 12V fuel pump mod and see if that helps any. Hope some of this helps.