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What is the lifespan of a noisy E30 fuel pump?

Discussion in 'E30 (1984-1993)' started by Brian A, Aug 29, 2009.

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    Brian A

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    I am currently am on long road trip. The fuel pump on my 1987 325i convertible (build date: Dec 1986) has begun to make noise (whirring sound and some clicking).

    How much warning does a fuel pump give before it quits? How long does a noisy fuel pump last (10 miles? 100 miles? 1000 miles?)? Unfortunately I am writing from Kings Canyon National Park. Nearest town is Fresno; nearest dealership is probably Bakersfield. Any advice how to "baby" a fuel pump?

    Other than that, things are fine. ($#%&^#).
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    Couldn't tell ya, but I do hope you make it hope. Hurts the bragging rights that such an old car can make such a long trip when your fuel pump goes on ya. :(
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    Brian A

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    Assessment Made - Car still running

    Just to document the troubleshooting for this, I also emailed Roundel Tech Talk and Mike Miller responded by morning. He gave (the always excellent) diagnosis and troubleshooting advice.

    My car has two fuel pumps; a main fuel pump mounted above the fuel filter which is in front of the driver's side rear wheel and an auxiliary fuel pump which is mounted in the tank itself (post 09/87 cars only had one main fuel pump in the tank). My main fuel pump is bomb-proof and runs almost forever; the auxiliary pumps don't last as long.

    Issue was which fuel pump was making the noise. I started the car in the morning (it started!) and the fuel system was quiet. I lifted the auxiliary fuel pump out of the tank with engine running. Quiet. I unplugged it. Same quiet. Auxiliary fuel pump was dead.

    I put it all back together and tried to drive out of King's Canyon National Park. The car did not balk. Since it was Sunday, there was nowhere to get the part. I was 6 hours from home and 8 hours from my next destination (Las Vegas) (I am headed to Grand Canyon Park to (hopefully) hike across the canyon from the North Rim to the South Rim).

    So far so good. No more fuel pump noise. Car is still running fine. I am planning to order an auxiliary fuel pump today at the Las Vegas BMW dealership for pick-up on route home.

    Only thing I'll add is that I kept my tank above 1/2 full all day yesterday; not sure this helps the solo main pump or not, but it can't do harm. The issue is trying to keep the main pump from cavitating.

    The guy at the parts counter at the Las Vegas dealership said that basically the auxiliary pump is to lift gas out of a near empty tank to the main pump. He said that if I kept my tank above half, I shouldn't need the auxiliary. I ordered it anyway since I am a long way from home and this is my only chance.

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