About Cars

Troubleshooting a 1997 BMW 528I Fuel Pump

1. Watch for your 528i to exhibit signs that the fuel pump is not working properly. Two key signs are the car refusing to start when you turn the ignition key and the engine stalling when you press the accelerator pedal to increase the BMWs speed.
2. Listen for the fuel pump to begin working when the BMWs battery is energized. Put the ignition key into the ignition and turn it one setting to the right so that the cars battery is on. If the fuel pump is working properly, it will begin sending fuel through the fuel lines as soon as the battery is working. You should be able to hear the pump from the drivers seat of the car. Be sure to perform this test in a quiet place or, if you are unsure whether you hear the pump working, have a second person turn the key on while you stand by the gas tank and listen.
3. Connect a fuel pressure gauge to the Schrader valve of the engine and check the fuel pressure of the car. The Schrader valve is near the top of the engine and looks very similar to an air valve on an automobile tire. Once the fuel pressure gauge is connected to the valve, turn the BMWs engine on and let it idle. Read the gauge to see if the car has the proper fuel pressure level. A 1997 528i should have between 51 and 58 pounds per square inch of fuel pressure in its fuel system.
4. Inspect the fuel pressure regulator to see if it is working properly. When the fuel pressure is too low on your BMW, the regulator may be faulty instead of the fuel pump. Leave the fuel pressure gauge attached to the Schrader valve and turn the engine on so it is idling. Gently squeeze the black fuel line running to the fuel pressure regulator and watch the fuel pressure gauge at the same time. If the fuel pressure increases while you are squeezing the fuel line the fuel pressure regulator needs to be repaired or replaced instead of the fuel pump.