C 2500 Suburban 2WD V8-6.5L DSL Turbo VIN F (1995)
Fuel Filter: Description and Operation
Fuel System
FUEL MANAGER/FILTER
The fuel manager/filter is an in-line type filter which combines several different functions. It acts as a fuel filter, water separator, water detector,
water drain, and a fuel heater.
The fuel manager/filter mounts on the rear of the intake manifold. 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 fining 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 lift pump diagnosis and
filter element replacement procedure. The fuel manager/filter also has a water in fuel sensor and a fuel heater.
Fuel Filter
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.
Water in Fuel Sensor
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 the filter housing and then turn the
"Water in 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.
Fuel Heater
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
flow to the injection pump. A control circuit inside the fuel heater completes the circuit for the heater element when it senses a temperature below
8°C (46°F).
