See Figures 1, 2, 3, 4, 5, 6 and 7
The electronic fuel injection system consists of 2 subsystems, the fuel delivery system supplies fuel to the fuel injectors at a specified pressure. The electronic control system regulates the flow of fuel from the injectors into the engine.
The fuel delivery system consists of an electric fuel pump, fuel filters, fuel pressure regulator an fuel injectors. The electric fuel pump, mounted in the fuel tank, draws fuel through a filter screen attached to the fuel pump/sending unit assembly. The fuel is then pumped to the engine compartment, through another filter and into the fuel injection rail. The fuel injection rail supplies fuel directly to the injectors. Constant fuel pressure is maintained by the fuel pressure regulator. The pressure regulator is mounted at the end of the fuel injection rail, downstream from the fuel injectors. Excess fuel supplied by the fuel pump is relieved by the regulator and returned to the fuel tank through the fuel return line. The fuel injectors spray a metered quantity of fuel into the intake air stream when they are energized. The quantity of fuel is determined by the electronic control system.
The electronic control system consists of the Engine Control Module (ECM) and the engine sensors and switches that provide input to the ECM. The Mass Air Flow (MAF) sensor monitors the amount of air flow into the engine, measures air temperature, controls the electric fuel pump and supplies this information to the ECM. Information is also supplied to the ECM regarding engine coolant temperature, engine speed and exhaust gas oxygen content. Based on the input information, the ECM computes the required fuel flow rate and determines the needed injector pulse width, then outputs an command to the fuel injector to meter the exact quantity of fuel.