Fuel Filter: Description and Operation

Fig 1 Top View Of Fuel Pump Module:

Fig 3 Side View -- Filter/Pressure Regulator:

Fig 2 Fuel Pump Module Components -- Typical:

DESCRIPTION
Two different types of filter/regulators are used.
- If a rubber grommet is located between the bottom of filter/regulator and top of fuel pump module (Fig. 21), it can be serviced separately.
- If this grommet is not used, it cannot be serviced separately The Fuel Pump Module assembly must be replaced. Refer to Fuel Pump Module Removal/Installation for procedures.


OPERATION
The regulator is calibrated to maintain fuel system operating pressure of approximately 339 kPa +/- 34 kPa (49.2 psi +/- 5 psi) at the fuel injectors. It contains a diaphragm, calibrated springs and a fuel return valve. The internal fuel filter is also part of the assembly. Fuel is supplied to the filter/regulator by the electric fuel pump through an opening tube at the bottom of filter/regulator. The fuel pump module contains a check valve to maintain some fuel pressure when the engine is not operating. This will help to start the engine.

If fuel pressure at the pressure regulator exceeds approximately 49.2 psi, an internal diaphragm closes and excess fuel pressure is routed back into the tank through the pressure regulator. A separate fuel return line is not used with any engine.