General System Description

Fig. 10 Electronic fuel pump & sender assembly. 1986 - 87 V6-183 & Late 1986 & 1987 Aerostar 4-140 EFI:

Fig. 11 Fuel pump wiring diagram. 1986 - 87 V6-183 & Late 1986 & 1987 Aerostar 4-140 EFI:

1986 - 87 V6-183 & LATE 1986 & 1987 AEROSTAR 4-140 EFI

The fuel pump is mounted on the fuel sender assembly inside the fuel tank, Fig. 10. Power to electric fuel pump is supplied by a fuel pump control relay, Fig. 11, which is controlled by the Electronic Engine Control (EEC) module. When the ignition switch is in the Off position, no power is supplied to the fuel pump system. Placing the ignition switch in the On position with engine not operating, will energize the EEC power relay, which in turn energizes the fuel pump control relay and the timing device located in the EEC module. The timing device in the EEC module will open the fuel pump ground circuit after approximately 1 second of operation, de-energizing the pump. This 1 second operation of the fuel pump is to pre-pressurize the fuel system. When the ignition switch is placed in the Start position, the EEC module will energize the fuel pump control relay to provide fuel for starting the engine. After the engine has started and the ignition switch is returned to the On position, the EEC module will supply power to the fuel pump control relay as long as engine speed remains above 120 RPM. When engine speed drops below 120 RPM or when the engine is stopped, the EEC module will open the ground circuit to the fuel pump control relay.
An inertia switch is also used with this fuel pump system. In the event of a collision, the inertia switch will open the fuel pump power circuit, which in turn will stop engine operation. Before the engine can be restarted, the inertia switch must be reset. On 4-140 engines, the inertia switch is located on the toe board to the right of the transmission tunnel. On V6-183 engines, the inertia switch is located in the engine compartment.
The fuel pump has the capability of of supplying 16.9 gallons of fuel per hour at 45 psi. System pressure is controlled by a pressure regulator located on the engine. If fuel system blockage is encountered, an internal fuel pump pressure relief valve will limit maximum pump pressure to 125 psi. The fuel pump also incorporates a check valve in the pump outlet to retain system pressure after engine shut down. This retained system pressure aids in preventing hot starting problems. The fuel pump internal components are protected by a nylon pickup element. This element will filter out contaminants which could damage the pump. The element will allow passage of a small quantity of water which may accumulate in the sump.
A special design fuel tank, with an internal pump cavity, is used with this fuel pump system. This design will provide sufficient fuel supply for proper engine operation during extreme vehicle maneuvers with low fuel tank fill levels.