1989 560SEL Won't start
 

I have had this car for over 10 yrs with no problems (193k miles). About 2 weeks ago my wife was driving along at about 30 mph and the engine just quite. When I arrived, about 20 minutes later, I started the car and drove home with no problem. I drove the car around for about a week with no problems (fast, slow, idle) everything was fine.

Then a few days ago about a 1/2 mile from the house at a stop sign the engine stopped. The battery & ABS lights were on. I shut off the car and it restarted about 30 seconds later. Running fine I took off and the engine quit about 1/2 mile down the road. It would not restart. I let it cool off and it started fine. Once up to 80 C it quit. I let it cool below 40 C and it restarted. Afte reaching just over 80 C it quit and now it won't start at all. If I put some fuel / starter fluid in the air intake and crank the engine will try to run for a couple of seconds.

I don't hear the fuel pump running when the key is turned on and I checked with a volt meter - no power to the fuel pumps. I took the OVP and fuel pump relay apart and both look like new. When I try to start the engine the speedometer will "jump" up to around 30 mph erratically while the engine is cranking.

Any help? Thanks

You mention having owned the car for 10 yrs. Has the fuel pump relay been changed during this time?

If not, I'd bet a buck that's your problem, especially since it restarts after a short while. If it didn't start until things had cooled off(maybe an hr.), I'd suspect the fuel pump. Just went thru this.

If the FPR is old, I wouldn't put much faith in appearance. Even if it isn't that old, the FPR provides power to the pump and you hear no priming sound, so..........

I suppose another possibility could be the elect. portion of the ign. switch.

Thanks I have a fuel pump relay on the way as I am sure it is original (never been changed while I have had the car). I will see if I can check the pumps (I don't think they have been changed).

Jim,
I totally agree with Mike on the relay. Also if you have owned the car for 10 years and know the pumps haven't been changed, do yourself a favor and change the pumps too. I know they are expensive, but trust me they are due for failure, and you don't want to put your wife at risk. You have to look at it this way. You are driving one of the finest MBs ever built for cheap, so you can afford to put a few bucks into the car. The pumps will cost less than two car payments on a new piece of crap. Actually if your pumps are drawing alot of current, they will take out your new relay.

Thanks for the help! Put in the new relay and it runs great. I agree with replacing the fuel pumps and it is a good chance they may have taken out the relay.

That's great and thanks for the feedback.

Yep, feedback is everything.

So many people come to this site with a problem, get help, and then never report back what fixed the problem.

1990 560 Sel
 

I've had a similar problem with my 90.
It quit on me a couple of weeks ago and I let it sit a few days. I went back a couple of days later, messed with the fuel pump(wiggled some wires) and it started right up. It drove fine for about 2 weeks then died on me as I was pulling into the parking lot.
After a little bit of troubleshooting.....I found there was no voltage to the pump, so I started testing the Fuel Pump Relay. I tried the pin 7 to pin 8 jumper. Wouldn't work. I did a voltage check to the female ends(jacks) of 7 and 8 and had nothing from either. I found jack 9 had voltage, so I put a jumper wire from pin 9 to 7 and 8 on the relay(providing voltage to both 7 & 8). Fuel pump worked perfect. Car ran fine....
I'm just worried that this could cause a problem, having the jumpers and all. The fuel pump only comes on when the key is on.
I'm pretty sure jack 7 or 8 should have voltage, but neither do. Would this be a problem with the connection to the relay base? I believe so...but I'm not sure. If it's not that, then it would have to be between the battery and the relay base. If anybody has any information on the wiring from the base to the batt, please let me know. Or any other tips for that matter.

Thanks

Paul,
Thanks for the backup comment. I would hate to think I was the only seasoned member of this forum who thinks people that don't leave feedback are rude.

Jerry,
You need a fuel pump relay and a set of pumps. When you moved the pumps, you got the armature started again. The worn out pumps took out your relay and will wipe out a new one if you install one. The way you have those pumps jumpered is a temporary fix to get you to a place you can have the repairs done. Those pumps don't draw enough current to warrant a relay so that isn't really a relay. It is a safety switch which is meant to shut the pumps off as soon as the engine stops. The way you have it jumpered now you could pump fuel out of a cut or ruptured fuel line at about 5 bar after an accident. If there is a spark, I doubt if there will be enough time to get the passengers out alive. Best get it corrected.:)

Autozen .I must say it helps if the problem is found by the owner , or the members helping to sort it out . Just as your looking to find out information, that takes time, then , only to be left high and dry. With no reply . And we wont know what the problem realy was. Or, if the help given was of any use.