Fuel Delivery
The fuel delivery sub-system uses a high pressure electric fuel pump mounted on the chassis. Pump delivers fuel from the fuel tank through a 2 micron fuel filter to a fuel charging manifold assembly. The fuel charging manifold assembly incorporates electrically actuated fuel injectors directly above each of the engine's intake ports. The injectors spray a metered quantity of fuel into the intake air stream.
A constant fuel pressure drop is maintained across the injector nozzles by a pressure regulator. The regulator is connected in series with the fuel injectors and is positioned downstream from them. Excess fuel supplied by the pump, but not required by the engine, passes through the regulator and returns to the fuel tank through a fuel return line.
All 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 vehicles' ECA. Air entering the engine is measured by a vane air flow meter located between the air cleaner and the turbocharger or fuel charging manifold assembly.
This air flow information and input from various other engine sensors is used to compute the required fuel flow rate necessary to maintain a prescribed air/fuel ratio for the given engine operation. The computer determines the needed injector pulse width and outputs a command to the injector to meter the exact quantity of fuel.