Fuel Pump: Description and Operation

NOTE: The complete fuel pump module is replaced when renewing the fuel pump.

The fuel pump is fitted inside the in-tank module (1 Fig. 1), which is fixed to the centre base of the fuel tank, via a rubber cradle (2 Fig. 1) and steel bracket (6 Fig. 1). The rubber cradle behaves as an acoustic baffle to deaden pump vibration and noise. There are three large tabs (3 Fig. 1) and one small tab on the module casing, which locate into slots in the centre recess of the rubber mounting (4 Fig. 1) this ensures that the pump can only be mounted in the correct orientation. The periphery of the rubber mounting incorporates four protrusions each having a locating slot (5 Fig. 1), three slots are large and one is small, which locate onto tabs on the steel support bracket (7 Fig. 1).

The fuel tank of AJ16 engined vehicles contains one fuel pump, supplying fuel to the normally aspirated engine and two fuel pumps, supplying fuel to the supercharged engine. They are regenerative turbine pumps supplied by Nippon-Denso. Nominal operating pressure is 3 bar (3.7 bar for supercharged engine) above the manifold depression and pump delivery is 90 litres/hour minimum at 13.2 volts, 3 bar outlet pressure. The pump(s) draw a nominal current of 7 amperes at 13 volts, 3 bar outlet pressure, ambient temperatures. Built in to the pump assembly is a over-pressure relief valve which blows at 4.5 - 8.5 bar.

The second fuel pump for the supercharged engine operates only in the higher speed range, switching on at 4000rpm and off at 3200rpm.

Fuel is drawn by the pumps from the fuel tank and is then supplied to the fuel rail via a 70 micron filter and the fuel feed line connected in series by fuel filter.

Fig. 1 Fuel Pump Module:

Fig. 2 Filter:

Fuel is pumped out of the module through a port at the top of the module (9 Fig. 1). There are two rubber moulded hoses connected to the top of the module, the short hose (10 Fig. 1) connects from the module's outlet port to the underfloor fuel feed pipe at the base of the fuel tank. The long hose (11 Fig. 1) connects the fuel return pipe to the module's return port.

Connections between the hoses and solid pipes are underneath the car. The only direct connection between pump module and the tank is at the evaporative loss flange via a two wire electrical connection (12 Fig. 1).

The fuel pumps are switched on and off by relays controlled by the engine control module (ECM).

NOTE: It is important to ensure correct orientation and fitting of fuel pump module with rubber mounting and steel support bracket.