Fuel pressure regulator Fuel pump relay (Fuel system)

Fuel pressure regulator Fuel pump relay

The fuel pressure regulator is a mechanical device The fuel pump relay is fed from the ignition relay and controlled by manifold depression and is mounted at controlled by the ECM. The relay is activated in the rear of the engine in the fuel rail. The regulator ignition key position 2 to prime the fuel system for a ensures that fuel rail pressure is maintained at a period of time controlled by the ECM. Failure of this constant pressure difference to that in the inlet relay will result in no fuel pressure. manifold, as manifold depression increases the regulated fuel pressure is reduced in direct proportion. Inertia fuel shut-off switch

When pressure exceeds the regulator setting excess The inertia switch isolates the power supply to the fuel fuel is spill returned to the fuel tank swirl pot which pump in the event of sudden deceleration. The inertia contains the fuel pick-up strainer. switch is located in the engine compartment. It is reset by depressing the central plunger at the top of the Failure of the regulator will result in a rich mixture at switch. idle but normal at full load, or a rich mixture resulting in engine flooding, or a weak mixture. Although the Engine immobilization fault will not illuminate the MIL, faults caused by the failure may be indicated. A coded signal is sent from the immobilization unit, located behind the instrument panel, to the vehicle Relay module ECM. If the coded signal does not match the signal expected by the ECM, the ECM immobilizes the The engine management system employs a relay starting and fuel circuits. module, which houses the main relay and the fuel pump relay.

Main relay

The main relay supplies the power feed to the ECM and, the fuel injectors (8 amps) and mass air flow sensor (4 amps). This relay is controlled by the ECM. This enables the ECM to remain powered up after ignition is switched off.

During the ’ECM power down routine’ the ECM records all temperature readings and powers the stepper motor to the fully open position. Failure of this relay will result in the ECM not being switched on resulting in engine not starting due to absence of fuel and ignition.