Fuel Supply
Fuel is supplied by chassis mounted or in-tank electric fuel pump. Some models use both in-tank low pressure pump and externally mounted high pressure pump. Pump delivers fuel from fuel tank through 20-micron fuel filter to fuel charging manifold assembly.
Fuel charging manifold assembly incorporates electrically actuated fuel injectors directly above each intake port. Injectors spray metered quantity of fuel into intake air. Constant fuel pressure is maintained to injector nozzles by pressure regulator.
Fuel pressure regulator is connected in series with fuel injectors and is positioned downstream from them. Excess fuel supplied by pump, but not consumed by engine, passes through regulator and returns to fuel tank through fuel return line.
On 1.9L, 2.3L, and 2.3L Turbo engines, all injectors are energized simultaneously, once every crankshaft revolution. On 3.0L and 3.8L engine, injectors are energized in 2 groups of 3, with each group being energized every other crankshaft revolution. On 5.0L engine with Sequential Fuel Injection (SEFI), all injectors are energized once every crankshaft revolution. Each injector is energized in sequence with ignition firing order.
ECA determines required fuel flow rate necessary to maintain prescribed air/fuel ratio for given engine operation by measuring quantity of air entering engine. Computer determines needed injector pulse width (period of time that injectors are energized) and energizes injector to meter quantity of fuel.
VAF system measures intake air quantity with vane airflow meter and integral air charge temperature sensor. Speed/density control system uses Throttle Position Sensor (TPS), Manifold Absolute Pressure (MAP) sensor and Air Charge Temperature (ACT) sensor to determine intake air quantity.