Fuel Injection System - Ford MPI: Operation: Notes

An on-board electronic engine control (EEC-IV) computer accepts inputs from various engine sensors. This information is required to maintain a prescribed air/fuel ratio throughout the entire engine RPM range. The EEC-IV system also compensates for changes in altitude.

The fuel delivery subsystem consists of an in-tank low-pressure pump, and a high pressure chassis-mounted electric fuel pump. Fuel passes through a filter before entering the low pressure pump. The fuel is filtered again after high pressure pump on its way to the pulse damper and fuel supply manifold. The pulse damper smooths the pressure variations in the fuel supply manifold.

The fuel injectors are mounted directly above each intake ports. When energized, the injectors spray a metered quantity of fuel into the intake air stream. pressure regulator maintains a constant fuel pressure. Excess fuel supplied by the pump, also passes through the regulator and returns to the fuel tank.

Two injectors are energized simultaneously, once every crankshaft revolution. The period of time that the injectors are energized (injector "on time" or pulse width) is controlled by the vehicle's Electronic Engine Control (EEC) computer. Air entering the engine is measured by a vane airflow meter located between the air cleaner and the turbocharger. This airflow information along with input from various other engine sensors is used to compute the required fuel flow rate.