Fuel system - MPi (page 5 of 7)

Fuel pressure regulator

The pressure regulator is a mechanical device controlled by manifold depression and is mounted on one end of the fuel rail. The regulator ensures that fuel rail pressure is maintained at a constant pressure difference to that in the inlet manifold, as manifold depression increases the regulated fuel pressure is reduced in direct proportion.

When pressure exceeds the regulator setting, excess fuel is returned to the fuel tank swirl pot which contains the fuel pump pick-up.

Inertia fuel shut-off switch

The electrical circuit for the fuel pump incorporates an inertia fuel shut-off (IFS) switch which, in the event of a sudden deceleration, breaks the circuit to the fuel pump preventing fuel being delivered to the engine. The IFS switch is situated in the engine compartment next to the ECM, and must be reset by pressing the rubber top before the engine can be restarted.

WARNING: ALWAYS check for fuel leaks and the integrity of fuel system connections before resetting the switch.