Fuel System - Overview

WARNING: This page is about a different car, the 2018 Ford F-550 Super Duty, 2018 Ford F-450 Super Duty, 2018 Ford F-350 Super Duty, and 2018 Ford F-250 Super Duty. However, it is still accessible from the selected car via links, so may be relevant.

The diesel fuel system consists of the following:

Fuel tubes
Fuel filters (located on the engine and on the fuel tank)
Fuel level sensor
Fuel tank filler pipe assembly
Fuel tank
High-pressure fuel system (located on the engine)
In tank diesel delivery module
Low fuel pressure sensor (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.

The electric FP (located in the diesel delivery module in the tank):

draws fuel from the fuel tank through a external fuel tank mounted filter.
circulates fuel at low vacuum through the 10 micron externally mounted fuel tank filter to the engine mounted secondary fuel filter and fuel injectors to initially fill the hydraulic couplers. The fuel is filtered through a 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 externally mounted fuel tank filter contains a thermal recirculating valve that, based on fuel temperature, allows the returning fuel to be sent back to the fuel tank.

Externally mounted fuel tank filter/Water Separator

The vehicle is equipped with a externally mounted fuel tank filter/water separator. The externally mounted fuel tank filter/water separator contains a fuel filter and water separator. Drain the water from the externally mounted fuel tank filter/water separator 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 externally mounted fuel tank filter/water separator as soon as possible to prevent damage to the fuel injection system.

Dual Fuel Tank Operation

If equipped with dual fuel tanks, the fuel tank delivery system operates independently and automatically. The fuel pump in the front fuel tank delivers fuel to the engine. When the fuel level in the front fuel tank drops below three quarters full, fuel automatically transfers from the rear fuel tank to the front fuel tank. Whenever there is fuel in the rear fuel tank, the front fuel tank level remains between half and three quarters full.