Fuel Charging and Controls

The fuel system used on the 6.0L direct injection (DI) turbo diesel engine is controlled by the powertrain control module (PCM).

The fuel system components consist of:
^ electric fuel pump.
^ high-pressure oil pump.
^ fuel filters.
^ oil pressure regulator.
^ oil pressure sensor.
^ fuel pressure regulator.
^ water in fuel switch/fuel heater thermostat.

Fuel to be supplied to the combustion chambers passes through the fuel conditioning module into the secondary fuel filter then to the cylinder head galleries, then through the electrohydraulic injectors.

Excess fuel not used by the engine bypasses the secondary fuel filter, flows through the fuel pressure regulator assembly, and returns to the fuel conditioning module.

Fuel Pump
The fuel pump is mounted in the fuel conditioning module mounted on the left hand frame rail.

Fuel Injectors:

Fuel Injectors

CAUTION:
^ Do not attempt to put battery voltage to the fuel injector or damage to the fuel injector will occur.
^ To prevent engine damage, do not use air tools to remove the fuel injectors. The clip that extracts the injector can dislodge and fall into the drain hole.

The engine uses an electrohydraulic injector as part of its fuel system. This PCM-controlled injector uses high-pressure lube oil to provide the necessary force to inject fuel into the combustion chamber at pressures up to 144 mPa (21,000 psi) at rated horsepower.

The injectors fits into a sleeved bore machined into the cylinder head. The injector bore intersects with a machined fuel passage that runs the length of the head. Each injector has two O-rings around the outer body, one above the fuel passage, and one below. A fuel inlet port between the O-rings allows fuel under pressure to enter the pressure amplification area of the injector. High-pressure engine oil enters the injector through the top. The high-pressure oil rail assembly is mounted on top of the fuel injector.

Fuel Pressure Regulator:

Fuel Pressure Regulator
Fuel pressure in the cylinder head fuel galleries is maintained by a fuel pressure regulator. The fixed orifice is an air bleed. It is the highest point in the fuel system. It allows the air behind the fuel pressure regulator to be vented to the fuel tank rather than be ingested in the fuel galleries. The fuel pressure regulator contains a spring-loaded poppet valve, which opens to allow excess fuel to return to the fuel conditioning module. Once back to the fuel conditioning module, the fuel is sent back to the fuel tank or to the engine, if the fuel conditioning module is in recirculation mode.







Oil Pressure Regulator
Fuel injection pressure is controlled by the Injection Control Pressure (ICP) system. The ICP system consists of the following:
^ injection control pressure (ICP) sensor located in the high pressure pump cover.
^ Injection Pressure Regulator (IPR) located in the high pressure pump cover.
^ powertrain control module

NOTE: The oil pressure regulator and oil pressure sensor are located under the turbocharger up pipe.