Fuel Delivery
Fuel is drawn through a filter sock on one end of the fuel pump and is forced out the opposite end. Two check valves are used. One of the valves relieves internal fuel pump pressure and regulates maximum fuel pressure output.
The other check valve is located near pump outlet. It restricts fuel flow in either direction when pump is not running. Fuel not used by the engine is returned to the tank by a fuel return line.
Power to the fuel pump is supplied through the ASD relay of the power module. When the power module receives a signal from the distributor during engine cranking, the module grounds the ASD motor, closing the contacts of the ASD. When the contacts are closed, power is applied to the fuel pump.
Whenever the distributor signal is lost, the module opens the ASD motor, which cuts power supply to fuel pump. This is a safety feature designed to prevent fuel flow should the vehicle be involved in an accident or if the engine stalls.