Land Rover Discovery TD5 fuel pump test and replacement. To test if the fuel pump has failed, there’s a simple test to do with a bulb and wire. The plug on the pump has 4-wires – 2 thin wires, which are the sender wires, and two thick wires, which are the live and earth for the pump motor. With the ignition on – the white wire should be live and the black wire should be earth. If there’s power to the pump, then it has failed and a new one will set you back around £180. Full article by Les Henson @tech archive LR4x4.com