Right Hand Drive
FUEL PUMP OPERATIONThe fuel pump used is an electric gear/rotor type pump. It is driven by a permanent magnet 12 volt electric motor that is immersed in the fuel tank. The pump is integral with the fuel sender unit. The pump/sender assembly is installed inside the fuel tank.
The fuel pump has a check valve at the outlet end that consists of a steel ball held against a seat by force applied from a spring. When the pump is operating, fuel pressure overcomes spring pressure and forces the ball off its seat, allowing fuel to flow. When the pump is not operating, spring pressure forces the ball back against the seat preventing fuel backflow through the pump.
Fuel system pressure is maintained at approximately 214 kPa (31 psi). This is when the pump is operating and vacuum is supplied to the fuel pressure regulator. If vacuum is not supplied to the pressure regulator, fuel pressure will be approximately 55-69 kPa (8-10 psi) higher. This may be due to a broken or clogged vacuum line. When the fuel pump is not operating, system fuel pressure of 131-269 kPa (19-39 psi) is maintained. This is done by the fuel pump outlet check valve and the vacuum assisted fuel pressure regulator.
FUEL PUMP CONTROL
The Powertrain Control Module (PCM) energizes the fuel pump through the fuel pump relay. Battery voltage is applied to the relay from the ignition switch. The relay is energized when a ground is provided by the PCM. The relay is located in the Power Distribution Center next to the battery. The PCM energizes the fuel pump through the fuel pump relay during all operating conditions.
When the fuel pump relay contacts close, the relay supplies voltage to the fuel pump motor. Circuit A141 from the relay supplies voltage to circuit A241. Circuit A241 connects to circuit F9 in the fuel pump motor. Circuit Z1 provides ground for the fuel pump motor.