Fuel Filter: Description and Operation
FUEL FILTER/PRESSURE REGULATORDESCRIPTION
FUEL FILTER
The combination Fuel Filter/Fuel Pressure Regulator (4) consists of a housing with an integrated filter element. The fuel flows through the filter from the outside to the inside. As a result, any impurities are trapped inside the filter.
FUEL PRESSURE REGULATOR
The combination Fuel Filter/Fuel Pressure Regulator (2) is located along side of the fuel pump as part of the fuel filter assembly. It is transversely mounted to a chassis crossmember (left-to-right).
OPERATION
FUEL PRESSURE REGULATOR
The Fuel Pressure Regulator is a mechanical device that is calibrated to maintain fuel system operating pressure of between 3.7 - 4.1 bar(54 - 60 psi) at the fuel injectors.
Fuel is supplied to the Fuel Filter/Fuel Pressure Regulator by the Electric Fuel Pump directly.
The fuel pump assembly contains a check valve to maintain some fuel pressure in the system when the engine is not operating.
If fuel pressure at the pressure regulator exceeds a set amount, an internal diaphragm closes and excess fuel pressure is routed back into the tank through the pressure regulator.
The Diaphragm Pressure Regulator (2) regulates the fuel pressure by means of the return flow (10) quantity to the fuel tank.
If the pressure rises above the set pressure, the diaphragm (6) is pressed further against the compression spring (4).
The valve (7) attached to the diaphragm opens the passage for the return flow further. If the pressure drops below the set pressure, the valve is closed again by the compression spring (4).
FUEL FILTER
The fuel flows through the Fuel Filter (1) trapping any fuel impurities that may lie in the bottom of the tank. The Fuel Filter can not be serviced separately from the pressure regulator, the entire Fuel Filter/Fuel Pressure Regulator must be replaced as an assembly.