Fuel Charging and Controls

Fuel Charging and Controls


Sequential Multi-Port Fuel Injection (SFI)

WARNING: Do not smoke, carry lighted tobacco or have an open flame of any type when working on or near any fuel-related component. Highly flammable mixtures are always present and may be ignited. Failure to follow these instructions may result in serious personal injury.

The fuel charging and controls system contains:

- a Throttle Body (TB).
- fuel injectors.
- a fuel rail.
- a fuel pressure relief valve.
- a fuel pump control module (located on the LH side of the crossmember above and forward of the spare tire).

The fuel charging and controls system is:

- a Sequential Multi-Port Fuel Injection (SFI) system.
- Pulse-Width Modulation (PWM).
- Mass Air Flow (MAF).

Fuel is metered into each intake port in a sequential firing order. Fuel injectors pulse to follow engine firing order, in accordance with engine demand on a tuned intake manifold.

The PCM controls the fuel injection system. Injector pulse width is varied to control the amount of fuel flow. Varying fuel pump output controls fuel pressure. The PCM commands the fuel pump control module, which directly controls the fuel pump. The TB is electronically controlled by the engine management system. Throttle plate angle is changed electronically in response to throttle pedal movements initiated by the driver.


Throttle Body (TB)

NOTICE: Do not hold the throttle plate open with any object that could scratch the bore or plate while servicing or cleaning the Throttle Body (TB), or the TB may be damaged. Refer to Throttle Body Service and Repair.

The TB:

- controls air supply to the intake manifold by electronically positioning the throttle plate.
- is not adjustable.
- must be removed from the vehicle to be cleaned.

Refer to Throttle Body Service and Repair.


Fuel Injectors

The fuel injectors:

- are electronically operated by the PCM.
- atomize the fuel as the fuel is delivered.
- each have an internal solenoid that opens a needle valve, which injects fuel into the intake port in the cylinder head.
- are deposit resistant.

For removal and installation, refer to Fuel Rail and Fuel Injector - Exploded View Fuel Rail and Fuel Injector - Exploded View and Fuel Rail Fuel Rail.


Fuel Rail

NOTICE: The fuel injectors and the fuel rail must be handled with extreme care to prevent damage to sealing areas and sensitive fuel-metering orifices.

The fuel rail:

- receives fuel from the fuel supply tube.
- delivers fuel to the fuel injectors.

For removal and installation, refer to Fuel Rail and Fuel Injector - Exploded View Fuel Rail and Fuel Injector - Exploded View and Fuel Rail Fuel Rail.


Fuel Pressure Relief Valve

The fuel pressure relief valve is used to relieve fuel pressure from the fuel system and for diagnostic testing.


Fuel Pump Control Module

The fuel pump control module:

- receives signals from the PCM.
- controls the duty cycle of the fuel pump.