Fuel Pump: Description and Operation

V12 engined vehicles are equipped with two fuel pumps located inside the tank. They are regenerative turbine pumps supplied by Nippon Denso. Nominal operating pressure is 3 bar above the manifold depression and pump delivery is 90 litres/hour minimum at 13.2 volts, 3 bar outlet pressure. The pump draws 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.

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.

The second fuel pump is controlled by the engine control module (ECM) and works of a mapped fuel map. The pumps 'switch on' time depends on the fuel requirement which is depending on the engine load.

Structure of Fuel Pump

Fig. 1 Fuel Pump Construction:

The fuel pump is turbine driven by a direct current motor through a coupling.