Fuel Delivery (XJS)

The fuel pressure regulator maintains constant fuel pressure in direct proportion to intake manifold vacuum. This is accomplished by attaching a vacuum diaphragm to the regulator.

When the ignition is switched to the ON position (engine not cranking), fuel pump is activated for 2 seconds (to raise pressure in the fuel rail) then shuts off. Fuel pump is reactivated when engine starts cranking.

Fuel pump is located inside the fuel tank. Fuel pump operation is controlled by the ECU. If an injector malfunctions and the ignition switch is on, system limits fuel pump operation to prevent flooding.