Section 03-04A: Fuel Charging and Controls, 4.9L Engine | 1996 Vehicles Equipped with 4.9L SFI Engines Workshop Manual |
An on-board powertrain control module (PCM) (12A650) accepts input from various engine sensors to compute the required fuel flow rate necessary to maintain a prescribed air/fuel ratio throughout the engine operational range. The powertrain control module then sends a command to the fuel injectors (9F593) to meter the appropriate quantity of fuel.
The system will automatically sense and compensate for changes in altitude (from sea level to mountainous regions).
The fuel delivery subsystem contains a high-pressure, in-tank fuel pump (9350). It delivers fuel from the fuel tank (9002) through a 20-micron fuel filter (9155) to a fuel injection supply manifold (9D280).
The fuel injection supply manifold incorporates electrically actuated fuel injectors directly above each of the engine's intake ports. The fuel injectors, when energized, spray a metered quantity of fuel into the intake air stream.
A constant fuel pressure drop is maintained across the fuel injectors by a fuel pressure regulator (9C968). The fuel pressure regulator is connected in series with the fuel injectors and is positioned downstream from them. Excess fuel supplied by the fuel pump, but not required by the engine (6007), passes through the fuel pressure regulator and returns to the fuel tank through a fuel and vapor return tube.