Question about 1998 Audi A4

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1998 Cabriolet 2.8 electrical noise

There's a loud humming noise eminating from the rear in the general area of the fuel tank or left side near the rear wheel. Possible fuel pump? When I use the power windows or top, the noise sounds as if the electrical system is straining to provide enough power. Runs great - no other issues. Any ideas? Thanks!

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  • tkw222 Sep 17, 2008

    Thanks for your help and ideas. The top motor seems to be operating properly, however, the relay "cut off control" is a possibility. We do notice a change in the noise's pitch (higher to lower) when operating any powered items (top, windows, A/C).

    The noise is almost constant - even at idle - and seems to be getting progressively louder over the past several months. There's always been somewhat of a "rich" fuel smell in the trunk and have often read/heard that Audi's are notorious for noisy full pumps, so assumed the sound and smell might be related. Thanks again - most appreciated!!



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Hi tkw222,

Have you checked the operating motor for the soft top?....It sounds very much like you may have a relay problem with the cut off control for that motor....have a good look and make sure that there's nothing fouling the operation of the unit...

The pump is probably an immersible type, which will then be mounted inside the tank....If it external, it still carries the fuel..... I would hope that you don't have a problem with that, as if it is working under high load, it would be over heating and that could be very dangerous..... Have it checked very quickly.... Once you're satisfied that it is NOT the pump....Take a friend with you and ask for that person to listen for the direction that the sound is emitted.....Also carry a rubber pipe and using it, your friend will be able to pinpoint the noise.... Once you know the place, you'll be able to identify the defective unit and take the relevant action.

Regards Johngee10

Posted on Sep 17, 2008


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