Need Info On Possible Electric Fuel Pump Problem

[Pwr2spare]

I have started to notice the fuel pump making a whirring sound, as the fuel lowers in the tank, the whirring gets louder. I've also noticed that the car shudders upon acceleration, like its not getting enough fuel. Whoever, as the engine warms up it runs fine. The car is a 1990 525i 5spd M20 engine. I don't think that the pump has ever been changed and the car has 285,000 k's. I also noticed that the inside of the tail pipes are a rusty colour and not the black or light gray that I normally see. :(

[shogun]

When have you changed last time the fuel filter? Maybe the pump needs a hell of pump pressure to run the fuel through the filter. Could be also a possibility, although the pump itself could also be due for replacement.
As for the black colour in the tail pipes: also here you have to check the usual wear parts on your car which should be replaced in regular intervals, spark plugs, maybe the oxy sensor which gets tired after about 60K miles, and all the other wear parts in the intake system, including the airbox filter etc.

[p_gill]

Power to Spare,

I had a similar problem on my 535 and it turned out to be the fuel pump.

I reccomend that you change the fuel filter and check other possible areas for the problem.

However I can help you with the fuel pump trouble shooting.



Here is what I did.

(note: gasoline is highly flamable so do not perform this test if you don't feel safe working around highly flamable liquids)

1. remove the flexible hose from the return line near the fuel pressure regulator

2. insert the line into a container

3. start the engine, run it for 3 to 5 seconds and check for flow (gasoline in the container)

4. If gasoline is not flowing past your regulator then either your regulator is bad or the fuel pump is bad.

5. Reassembly the return line, restart the engine and check for leaks.



There is a standard flow rate in the Bently that is supposed to be coming out of the regulator into the return system.

In my case when the fuel pump went bad there was no flow.

Remember the fuel comes out of the regulator so keep the rubber hose connected to the regulator and disconnect it from the return line.

Good Luck

Paul

89 535

[Pwr2spare]

Many thanks for info. I'll be looking into it this week.