BMW E28 fuel pump and fuel pump relay
Where are the E28 fuel pump and fuel pump relay located?
The pump is under the car in front of the tank on the right, next to the fuel filter. The fuel pump relay is in the engine bay next to the fuse box, a large black relay. The relay is controlled by the ignition feed.
E28 fuel pump does not hum with the ignition on – what is wrong?
With the ignition on, the pump should hum for a few seconds while it builds up pre-pressure. If the humming is missing, first check the pump's power supply: the fuse, its contact, the relay socket and the battery terminals. The solder joints inside the relay can also come loose from vibration.
How can I test the fuel pump relay?
Bypass the relay with a jumper wire. If the pump starts to run, the relay is faulty. If the relay clicks but the pump does not run, the fault may be in the relay socket. A loose battery terminal can also cut the power and stall the car.
Is continuous humming from the pump normal?
With the engine running the pump should run continuously and receive about 12 V. Only a short hum is normal when the ignition is first switched on. If the pump hums briefly and the car does not start, check the voltage at the pump.