Fuel delivery system (Fuel Pump): Description and operation

Fuel Pump

The fuel pump is electrically operated and is located in the top face of the fuel tank. A notched locking ring retains the fuel pump in the tank and requires a special tool for removal and installation. The fuel pump is housed in a plastic body which incorporates coarse and fine filters. The fuel pump is located in a larger housing which is the swirl pot. The swirl pot maintains a constant fuel level at the pump pick-up.

A pressure regulator which regulates the pressure output of the pump to 3.5 bar is located in the pump housing.

If the pressure exceeds this setting the regulator relieves excess pressure back to the swirl pot. This ensures that the fuel rail and the injectors are supplied with a constant pressure.

An access panel below the rear passenger seats provides access to the fuel pump for maintenance. The top face of the fuel pump has an electrical connector which supplies power and ground to the pump and the rotary potentiometer for the fuel gauge. Two quick fit couplings provide attachment for the fuel feed and the vent pipes.

Fuel Filter

A fine mesh filter is fitted within the fuel pump assembly. This should be renewed at 120,000 mile (200,000 km) intervals.

Injectors

Four injectors held between the fuel rail and the inlet manifold. The injectors are sealed to the fuel rail and the inlet manifold by O-ring seals. Each injector supplies one cylinder with fuel. The injectors receive pressurized fuel from the fuel pump via the fuel rail. The Engine Control Module (ECM) is responsible for the timed injection duration of each injector. The injectors supply a finely atomized spray of the fuel into the cylinder which is mixed with the air prior to ignition.

Accumulator

An accumulator is attached to the right hand end of the fuel rail. The accumulator acts as a damper to damp pulses from the pump and ensure that the fuel pressure in the rail and to the injectors is constant. The accumulator is connected by a pipe to the inlet manifold from which it receives a vacuum to aid the damping process.