Fuel Charging and Controls
FUEL CHARGING AND CONTROLSFuel System
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.
- injection pressure regulator valve.
- injection control pressure (ICP) sensor.
- fuel pressure regulator.
- water in fuel switch/fuel heater thermostat.
- fuel injection control module (FICM).
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 and 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 LH frame rail.
Fuel Injectors
CAUTION:
- Do not attempt to apply 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/FICM-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.
Fuel Injectors:
The injector 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-ring seals around the outer body, one above the fuel passage and one below. A fuel inlet port between the O-ring seals 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 in the cylinder head fuel galleries is controlled 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 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.
Injection Control Pressure System
Fuel injection pressure is controlled by the injection control pressure (ICP) system. The ICP system consists of the following:
- ICP sensor mounted in the right valve cover
- Injection pressure regulator (IPR) valve located in the high-pressure pump cover
- Powertrain control module (PCM)
- High-pressure oil pump