The fuel manager/filter is an in-line type filter which combines several different functions by acting as a fuel filter, a water separator, a water detector, a water drain, and a fuel heater.

The fuel manager/filter mounts on the frame. The filter housing has an inlet fitting connecting to the pipe/hose from the lift pump and an outlet fitting connecting to the fuel injection pump with a hose. A third fitting connects through a hose to a drain valve mounted on the water crossover/thermostat housing.

The fuel manager/filter has a replaceable element. The element has an air vent valve on its top surface that is used during the lift pump diagnosis and the filter element replacement procedure. The fuel manager/filter also has a water in fuel sensor and a fuel heater.

The fuel filter element separates particles larger than 10 microns (0.00039 in) from fuel moving through it under lift pump pressure. Filter action is very critical to the operation of internal parts of the fuel injection pump.

The design of the fuel manager/filter includes an area that allows water droplets (as small as one micron) to separate from the fuel and collect in a lower portion of the housing. The water in fuel sensor will detect a certain amount of water in the fuel inside of the filter housing and then turn the Water the Fuel lamp ON in the instrument cluster.

When the ignition switch is first turned to the run position, the Water in Fuel lamp will come ON for 2 to 5 seconds. This action provides a bulb check.

The fuel heater operates when the temperature of fuel at the inlet of the filter housing is cold enough to possibly cause waxing that could restrict the flow to the injection pump. A control circuit inside of the fuel heater completes the circuit for the heater element when the fuel heater senses a temperature below 8°C (46°F).