91 560 SEL stops Running
 

I have a 91 560 SEL that the engine stops running intermittently. This just started this week and has happen three time. I'll be driving and all of a sudden the engine stops. If I wait about 15 mins it will start again. It just happen again today and even after waiting about 45 mins is wouldn't start. I had it towed home, and sure enuff as soon as the tow truck drove off it started. When the engine stops it still turns over fast enuff but won't start. So its not getting spark or fuel is my first though.

Any ideas where I should start looking at?


Thanks Bob

Fuel pump relay
 

I have an 1989 560sel that had the same problem. I replaced the fuel pump relay and the problem was corrected.

Fuel Pump Relay
 

Thanks for the reply Jim.

The fist time it stopped running I did check all the fuses under the hood and gave the relays a thump. So it just may be the problem. I'll lay hand on it tomorrow and check the relay connections are clean. I don't remember hearing the pump running. But I normally don't hear it if the cars been running for awhile. Only after it sits overnight or for a long time do I hear the pump.

Thanks again. Bob

After spending some time searching and reading on the forum. It does indeed sound like it could be the FPR. So my question now is. On my car where is the FPR located?


Thanks Bob

B/w the bulk head and the fire wall. Towards the drivers side from center, you'll see two black boxes, one will say Klima the other will have 6000 written on it. The 6000 is your man (relay)!.

I would recommend either genuine new or beckman re manufactured. Stay away from the KAE's.


Jonathan

Thanks for the reply Jonathan,

I was just outside looking for it and noticed the two black boxes and figured that one of them was the FPR. I pulled both out and check the contacts. Sometimes a little corrosion on the contacts will cause problems with relays. But still could be the contacts inside the relay or connections inside. On the bright side while under the hood I noticed a small vacuum line that was broken. I patched it with a peace of silicon tubing and now the idle has smoothed out. I had a very small lopping at idle before.

Thanks Bob

Quick update,

I was able to ID the FPR with the help of Jonathan and checking the part number at GermanStar.

I pulled the relay and found that the cover will just pop off with a little work.

After looking inside I don't understand why they call this a relay. Yes it does have two relays inside a small one and a bigger one. But there is also a bunch of other solid state components in there. I traced the 30 and 87 pins to find out the little one is used for the fuel pump. Looked the whole thing over under a magnifying glass but didn't see anything that looked bad. With a very small peace of sandpaper I cleaned both relay contacts and all the pins.

I really won't know if the FPR is the problem but I'm going to order one from GermanStar. At $119.00 its a small price to pay for the peace of mind.

Thanks everyone for the help.

Bob

Fuel pump relay
 

Before I replaced mine I took it apart and looked for cracked solder, etc. I did not find any either but replacement took care of the problem for my 89 560.