Operation CHARM: Car repair manuals for everyone.

Fuel Pump




Fuel Pump

The fuel pump is located in the fuel tank. It is switched on and off by means of a relay and delivers the fuel via the fuel filter to the fuel distributor pipe.

Fuel pump relay
The control unit can only monitor activation of the relay but not of the pump itself. A safety circuit ensures the relay can only be activated with the engine running and only shortly after switching the ignition lock to position 2 in order to build up pressure.

Once the engine shuts down, the DME control unit no longer recognized engine speed and immediately switches off the relay. This ensures that the fuel pump cannot continue running when the engine turned off.