1994 SL600 will not start - PeachParts Mercedes-Benz Forum

clayfood123 · #1 10-22-2006, 10:45 AM

I am new here but have been reading a lot of post trying to figure out the problem with my 1994 SL 600. I have owned the car for about 6 months without any incidents. The Mercedes shop checked the car shortly after purchased and they said everything looked good. Here is a brief outline of the problem. The other day I was going to pick up my daughter and was on the open road (55 mph). The car shut off, slowed down but started back up. 15 minutes later the car shuts off, slows down and stops (check engine light comes on). I wait for about 5 minutes and the car starts and I'm rolling down the road again. 10-15 minutes later...the same thing (the cars shuts off, slows down but starts back up before stopping). No check engine light!!! Understand, I am worried because several people told me I did not need nor could I afford a SL600. After I picked up my daughter the car ran fine for the next 50 miles. This afternoon (a week later) I go to start the car, it starts but runs terrible for about 10 seconds and then it cuts off. I try 4-5 times to start but no success. The car turns over fine but no attempt at starting. Hope someone has good news for me. Thanks in advance.

snowbilt · #2 10-22-2006, 02:07 PM

Have you by chance got new tires and/or wheels recently? Sometimes if the tires and wheels are not all the right size it will cause it to go into "limp mode" There have been several posts on this problem. Anyone else got any ideas?

page62 · #3 10-22-2006, 03:21 PM

I don't know squat about SL600's, but that sounds like a fuel pump to me. Or perhaps it's a bad relay, like a fuel pump or OVP relay.

clayfood123 · #4 10-22-2006, 03:28 PM

Thanks,
I was wondering about the OVP relay. Anyone else??? I tried to start it again this morning and it cranked but then cut off again. Can anyone tell me where the OVP relay might be located.
Clay

Lee Blaik · #5 10-22-2006, 04:25 PM

The culprit is most likely the OVP relay.
Try to bypass it and see if it'll runs OK.
Than you'll know.
Good luck...Lee

clayfood123 · #6 10-22-2006, 05:32 PM

Any info on how to bypass the OVP relay???

Roncallo · #7 10-22-2006, 05:35 PM

Quote:

Originally Posted by snowbilt

Have you by chance got new tires and/or wheels recently? Sometimes if the tires and wheels are not all the right size it will cause it to go into "limp mode" There have been several posts on this problem. Anyone else got any ideas?

Limp home mode will only cause the engine to run on six cylinders. It will actually run so well in limp home mode that some people dont even know they have a problem. You still have about 150 HP in limp home mode. It should not stall. I agree with one of the other post. Most likely fuel pump related, possibly pump or pump relay related.

I'm not sure what the OVP relay does. It sound like something that would cut the alternator current in an over voltage situation. If thats the case the fuel pump should be still able to function on the battery???

In any case you are very lucky that the pronblem is repeatable enough for the problem to be found. I went through hell with a Ford Taurus that had a bad relay on a semi weekly basis.

John Roncallo

ctaylor738 · #8 10-22-2006, 07:29 PM

The OVP relay provides a constant voltage to the engine electronics. It also has a fuse that will blow to protect against shorts. If the relay or the fuse goes out you will have a high idle and probably an ABS light.

This sounds like a fuel pump relay to me. Can you have someone crank the engine while you put your hand on the pumps to see if they are vibrating and getting power?

clayfood123 · #9 10-22-2006, 09:01 PM

I will try to take a closer look at everything tomorrow. I haven't noticed a high idle because the car won't start. When the car was running...it ran perfect. Just before the car would cut off running down the road there was plenty of power and purring like a kitten. I want to thank everyone who is trying to help me with this problem.

kjoske · #10 10-23-2006, 01:28 AM

Locate the fuel pump relay (usually by the firewall ) and shake it to see if it's loose; if starts and runs OK after you fiddle with it then its a loose relay; no need to change it (expensive if bought from MB dealer). Buy some bayonet style sleeves from the auto parts store and insert one or two in the electrodes to tighten it up and then everything will be OK. Has happened to me twice and this has been the cure.

Carlos Serrano · #11 10-23-2006, 12:55 PM

If it was a later model I would have to guess crankshaft positioner sensor,
Bosch F6010-51307 $161.00 at Fastlane, top of the page. Just a guess.

bobterry99 · #12 10-23-2006, 08:43 PM

I would read the diagnostic codes and see what they tell you. This requires a $1.29 LED from Radio Shack or some other device. If you want help with this, search the archives or send me an email.

clayfood123 · #13 11-03-2006, 08:30 AM

The car started the other day and I moved it. I was happy but when I went out this morning to take for a drive all it would do was turn over like it wasn't getting any fire. Turns over with no problems but doesnt try to start. HELP>

ctaylor738 · #14 11-03-2006, 12:13 PM

Did you check out the fuel pump relay as you were advised?