Yesterday my '89 300CE refused to start after shutting engine off for short time. Car started up fine cold after sitting a day but I had to return back home as I forgot to take something. Turned car off for 30 seconds- 1 minute and then went to restart but it just cranked and would not start. I went and wiggled the fuel pump relay and went back to try and it started right back up. How do these things go bad? I hear them causing problems when they get older so I want to replace mine right away. What brand is best? Looks like there are a couple to choose from including Kaehler, Kostal (OEM) and Mercedes.

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1989 300CE

Had this problem on my 84 500SEL. Turned out to be a cracked solder joint on the circuit board inside the fuel pump relay. Re soldered, and all has been fine for 10+ years.

Paul

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84 500 SEL (307,xxx miles)

Mosty it is the solder joints on the board which go bad and can be resoldered back to normal . frequently its the starting and stalling faults that the relay causes.
If you get hot engine starting problems which go away as the engine cools down then you may need to fit a new fuel accumulator near the fuel filter.
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I am going to go ahead and replace the relay since I don't have a soldering gun or know how to repair. There is the KAE ($84) and Kostal ($123) for the aftermarket replacements from our host. Does anyone have any recommendations/experience as to which one is better?

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1989 300CE

go to a boneyard and get one for five dollars

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1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


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The risk there is you might only get 5 minutes of life out of it.

4 years ago, mine gave up the ghost & I had it towed to the dealer for proper diagnosis & repair. Last summer I had the exact same symptoms* & I took it to the dealer. He asked me if I wanted him to replace the FPR. I said no, check & give the car normal servicing. It was due. They replaced the ignition coil (corroded) & wires. The problem has not returned in a year.

* Car goes dead and stalls while moving. Pull over (or quickly shift to neutral), turn ignition off, then restart. I have never had hard start when hot problems with mine (88CE)