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Old 09-03-2003, 12:08 PM
JohnUK JohnUK is offline
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Join Date: Sep 2003
Location: York UK
Posts: 7
Fuel Pump Relay - Dry Joint photo

After suffering the symptoms of random fuel starvation on my 1990 230CE, I found enormous help on this forum and fixed the problem in around five minutes. By way of a thank you, and for the benefit of those who have never seen a dry joint on a printed circuit board, here is a photo of the fuel pump relay board with a zoom in on a classic dry joint on one terminal of the relay. A bit of heat and a blob of fresh solder and the pump ran first time.

Although not actually measured, I suspect that this joint is subject to quite a high current load even with a good pump. If this is the case, the fault is almost bound to develop at some time or other on most cars and I would urge all readers to check this relay periodically. I consider a sudden failure of the fuel pump to be as dangerous as a blowout and worthy of a routine check. Luckily, the engine cut out late at night on a quiet road, not while I was overtaking a fuel tanker at 70mph!

By the way, the relay location on my W124 230CE is behind a pull-out plastic shroud behind the battery (not behind the fusebox as I first thought, duh).

Cheers to all

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Fuel Pump Relay - Dry Joint photo-w124_fpr_dryjoint.jpg  
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