6.7L Diesel

Fuel System - Diesel Engine

The diesel fuel system consists of the following:

- Fuel tubes

- Vapor tube (midship fuel tank)

- Fuel filters (located on the engine and in the fuel conditioning module)

- Fuel level sensor

- Fuel tank filler pipe assembly

- Fuel tank

- Fuel tank selector switch (if equipped)

- Fuel tank selector valve (if equipped)

- High-pressure fuel system (located on the engine)

- Diesel fuel conditioning module (located on the LH frame rail)

- Inertia Fuel Shutoff (IFS) switch (located on the RH side of the instrument panel)

- Low fuel pressure switch (located on the supply line between the engine mounted fuel filter and high pressure pump)

The fuel system for the high-pressure common rail direct injection turbocharged diesel engine:

- is controlled by the PCM.

- utilizes a diesel fuel conditioning module, which contains an electric Fuel Pump (FP) and incorporates a fuel filter and water separator assembly.

The electric FP (Fuel Pump) :

- draws fuel from the fuel tank.

- circulates fuel at low pressure through the 10 micron fuel filter located in the diesel fuel conditioning module to the engine mounted secondary fuel filter and fuel injectors to initially fill the hydraulic couplers. The fuel is filtered through the 2 to 4 micron engine mounted secondary fuel filter, and then supplied to the high-pressure fuel injection pump. Fuel is returned from the injectors through the fuel injector return hose and combines with fuel being supplied to the inlet of the engine mounted secondary fuel filter. Fuel that is returned from the fuel rail combines with fuel being returned from the high-pressure fuel injection pump and passes through the frame mounted fuel cooler to the diesel fuel conditioning module. The diesel fuel conditioning module contains a thermal recirculating valve that, based on fuel temperature, allows the returning fuel to be sent through the fuel conditioning module or sent back to the fuel tank.

Fuel Filter/Water Separator

The vehicle is equipped with a diesel fuel conditioning module. The diesel fuel conditioning module contains a fuel filter and water separator. Drain the water from the diesel fuel conditioning module at the recommended maintenance intervals. Refer to the Owner's Literature for the maintenance intervals.

While the engine is running a water in fuel indicator on the instrument panel or a "Water in Fuel, Drain Filter" message on the instrument panel message center will alert the operator. When this occurs drain the water from the diesel fuel conditioning module as soon as possible to prevent damage to the fuel injection system.

Fuel Tank Selector Switch/Valve

If equipped, the fuel tank selector valve and fuel tank selector switch allows the use of 2 fuel tanks. When the fuel tank selector switch is in the front position, the fuel tank selector valve will allow fuel to flow from the auxiliary fuel tank. When the fuel tank selector switch is in the rear position, the fuel tank selector valve will allow fuel to flow from the aft-of-axle tank. The fuel gauge will read the correct amount of fuel in each tank depending on which tank is selected with the fuel tank selector switch.