Fuel Pump: Description and Operation

Escort, Lynx, EXP, Tempo, Topaz, Sable & Taurus

The fuel tank on these models has an internal pump cavity in which the fuel pump and sender assembly rest. This design provides satisfactory operation during extreme vehicle operation.
The fuel pump is mounted on the fuel sender assembly within the fuel tank. This assembly includes a check valve which is located between the fuel pump and the outlet tube of the assembly. The function of this valve is to maintain pressure in the system after the vehicle is shut down. The fuel pump is protected at its inlet by a nylon pickup element. This nylon element filters dirt and contaminants which could plug or damage the internal pump components while at the same time, allowing passage of small quantities of water which may accumulate within the fuel tank sump. The electrical system has a fuel pump control relay which is controlled by the EEC-IV module, which provides power to the fuel pump under various engine operating conditions. When the ignition switch is in the OFF position, the contacts of the EEC-IV power and fuel pump relays are open. When the ignition switch is first turned to the ON position, the EEC-IV power relay is energized, closing its contacts. Power is provided to both the fuel pump relay and a timing device within the EEC-IV module assembly. When the ignition switch is turned to the START position, the EEC-IV module operates the fuel pump relay to provide fuel for starting the engine. After the engine starts, the ignition switch is returned to the ON position, power to the fuel pump is again supplied through the fuel pump relay. The EEC-IV module senses engine speed and shuts off the fuel pump by opening the ground circuit to the fuel pump relay when the engine stops, or when engine speed is below 120 RPM.