303-04B Fuel Charging And Controls- 4.4: Description And Operation (page 2 of 4)

The major components of the fuel charging and control system comprise an intake manifold, a fuel pump, a fuel rail and 
eight injectors. The fuel pump supplies fuel from the tank at a constant pressure, via a pipe routed along the side of the 
transmission, to the fuel rail. The fuel rail distributes the fuel equally to each of the eight injectors. The fuel injectors, which 
are controlled by the Engine Control Module (ECM), are installed in the fuel rails on each side of the intake manifold. A 
cross over pipe connects the two fuel rails together at the front of the manifold. A Schraeder valve provides a pressure 
test connection for maintenance. 
 

INTAKE MANIFOLD 

The intake manifold is located on top of the engine between the two cylinder banks and is manufactured from a composite 
material. The manifold comprises a central chamber with eight tracts leading to the inlet ports on the engine. The air 
intake manifold is secured to the cylinder heads via 10 bolts. 
 
Rubber gaskets, located in channels in the intake manifold, seal the joints between the ducts and the cylinder heads. For 
additional information, refer to   

Intake Air Distribution and Filtering

 (303-12B Intake Air Distribution and Filtering - 4.4L) 

FUEL PUMP 

The submersible electric fuel pump is attached to a carrier and is located at the bottom of the swirl pot inside the fuel tank. 
The fuel pressure regulator, which controls the fuel pressure in the feed pipe to fuel rail, is located in the fuel manifold in 
the fuel tank. For additional information, refer to   

Fuel Tank and Lines

 (310-01B Fuel Tank and Lines - 4.4L) 

THROTTLE BODY 

The electronic throttle body controls the engine torque and is located on the air intake manifold. It's main components are, 
an electronic throttle control valve, Accelerator Pedal Position (APP) sensor and the ECM. 
 
The APP sensor determines the driver demand to control throttle opening. This value is received by the EMS and the 
throttle is then opened to the correct angle by means of an integral electric motor. Sensors in the throttle body are used to 
determine the position of the throttle plate and the rate of change in its angle. For additional information, refer to   

Electronic Engine Controls

 (303-14B Electronic Engine Controls - 4.4L) 

Induction Elbow 

The induction elbow provides the interface between the electronic throttle body and the intake manifold. Connections on 
the induction elbow provide vacuum take off's for various vehicle systems. A boss on the rear of the elbow accommodates 
the Exhaust Gas Recirculation (EGR) valve. 
 

FUEL RAIL