Fuel Pressure Regulator: Description and Operation

Intake Manifold:

PURPOSE
Maintains fuel pressure at 36.3 psi (250.1 kpa) above manifold pressure.

LOCATION
On the L.H. injector rail.

OPERATION
Fuel flows from the pump, through the lines, to the injectors and to the pressure regulator. Fuel pressure acting on the diaphragm opens the return line orfice to the fuel tank. As manifold vacuums lowers (during accel), the spring in the diaphragm closes the passage, increasing fuel pressure.
As manifold vacuum increases, the spring tension is overcome and the orfice is opened, allowing more fuel to return to the tank, lowering fuel pressure.