560SL won't start - sometimes

[joselu43]

88 560SL 200,000 miles +, runs fine, uses oil. This is my wife's car. She uses it as a daily driver. Took it to work day before yesterday and had no problems, except that after work she stopped on the way back to visit with a friend. After an hour or so, when she tried to continued home, she had problems. The car would start and inmediately die, she tried several times and the same thing happened. She called me and by the time I got there, the car started without any trouble. The following day she took my car to work and I drove the SL. Had no trouble in the morning when I drove it on errands for a couple of hours. In the afternoon, after a couple of hours off, it happenned again. Car would start and inmedialtely die. If given gas it would rev up and then die, no matter what I tried. In the evening she started without problems.
The fuel filter is new (couple of months old), and I had no hints of trouble.
Searching this forum I read about acumulator problems, pump problems, etc but nothing seems to fit here. Any suggestions? -- Thanks.


JL

[halman2228]

The OVP can start getting flaky and cause intermittent (read: Hard to Figure Out) troubles.

Search some of those threads to see if that could be a/the cause.

Another wild ass guess: fuel pump relay getting goofy?

Kevin

[ctaylor738]

Agree. Fuel pump relay.

[joselu43]

Today it started fine. Drove to our annual Christmas party without problem. On the way back the engine cut out a couple of times while at speed. When going slower, it actually died a couple of times but restarted without problems. Is this consistent with your faulty relay diagnosis? Seems to me that it is definetly a fuel supply problem.
In the meantime, I will start looking for the relay and learning about it.
Thanks for your replies.


JL

[page62]

Fuel filter and/or clogged fuel pickup screen in tank.

[halman2228]

..for fuel starvation due to clogging filter and screen (imagine swirling crap in liquid that disperses without flow and pressure but gets sucked against the screen/filter under pressure). Needs to be changed anyway as a maintenance item so you wouldn't be "throwing parts" at it for naught.

Smarter people than me (ctaylor above, for instance) can tell you how to jumper the relay with a temporary fused jumper to verify or rule out the relay (forum search - its been said before).

If that (FP Relay) isn't the cause, get a new OVP - it isn't that much and if that isn't the problem, you'll have a spare in the glove box for this common failure (again, common enough that its almost a guarantee you'll need one, much like a "maintenance" item).

Not that you will satisfy the wife with explanations about life expectancies of small electrical parts subjected to the elements of riding around under the hood of a car for 200K miles, but if one of these three items is the cause/cure - it is pretty remarkable (overall reliability that is) isn't it?

I'm not thinking this is a tough one to fix - but it will be tough to get the wife to trust it again if you don't resolve it quick.

Merry Christmas
Kevin

[joselu43]

The fuel filter is new, less than a couple of months old, so I would think it should be OK. I am thinking of pulling the relay and inspecting it, and search for instructions on how to check it as suggested by Chuck and others. Correct me if I am wrong, but I belive it is behind the glove box?
The point about the wife is well taken. When she first called she wanted me to tell her over the phone what was wrong with the car! ... She loves the car though so I am sure it will work out all right. Thanks for the help.


Jl

[joselu43]

That's what it says in the unit I think is the fuel pump relay. It is a 10 pin unit, so that checks. Anybody can comfirm? Also can it be open? Unit looks ok from the outside. Thanks.

JL

[joselu43]

Das Schaltgerat fur Kraftstoffpumpe was the problem! I followed Chuck's intructions on another thread and hooked wires to terminals 7 & 8, closed the circuit and the car started fine. Ordered a new FPR ($93, not too bad), got it today, installed it and the car runs fine.
Just wanted to let you know and thank you for your help. I am always amazed at the amount of knowledge you guys have.
Thanks again!

JL