Fuel Pump: Description and Operation

Fig. 1 Electric fuel pump assembly. Front wheel drive models w/single point & multi-point fuel injection. Exc. Shelby w/turbocharged engine:

Fig. 2 Electric fuel pump assembly. 1987-88 front wheel drive models w/single point & multi-point fuel injection. Exc. 1987-88 Shelby w/turbocharged engine:

Fig. 3 External mount electric fuel pump assembly. 1985-88 Shelby w/multi-point fuel injection:

Fig. 4 Internal mount electric fuel pump assembly. 1985-88 Shelby w/multi-point fuel injection:

The fuel pump used in the EFI system, Figs. 1 and 2, is a positive displacement, roller vane, immersible pump with a permanent type magnet electric motor. The fuel is drawn in through the filter sock and pushed through the electric motor to the outlet. The pump contains two check valves. One valve is used to relieve internal fuel pump pressure and regulate maximum pump output. The other check valve located near the pump outlet, restricts fuel movement in either direction when the pump is not operational. Operating voltage is supplied to the pump through the Auto Shutdown (ASD) relay.
On Shelby turbocharged models are equipped with two electric fuel pumps. One pump is mounted in the fuel tank and the other is mounted outside the fuel tank, Figs. 3 and 4.