Question-------------------------
Followup To
Question -
Hi,
I've got a 1991 MBZ 300SL. The basic problem is simple, it won't "start" or even attempt
to start. We've ran a lot of test. So far, we've found good compression, good ignition spark, and plenty fuel.
The cam timing is good. I have 2.5 bar at the upper chamber while sitting, and 6 bar pressure while cranking. I think that may be too high.
While cranking you can really smell the fuel.
So far we've replaced the cam position sensor, crank position sensor,
coil, cap, rotor, wires, plugs, idle speed motor, used fuel distributor, fuel pressure regulator, fuel filter and coolant sensor.
The problem with this older (1991) model MBZ is the lack of ECU/DME diagnostics.
Any ideas or suggestions on what else I can try to look for? Thanks in advance for any help you may be able to provide.
Thanks,
Peter
Answer -
If the wire harnesses have not been replaced under the MB recall, that is your starting point.
MB Engine Wiring Harness Failure
http://www.mercedesshop.com/shopforum/showthread.php3?p=927185#post927185
Monitor the battery voltage while cranking, if it falls too low the OVP relay (Over Voltage Protection relay) drops out for ECU protection.
Did you bleed the air out of the used fuel distributor, all the way to the injectors?
You can destroy a battery and starter trying to crank bleed that much air through the injectors.
Are the spark plugs wet or dry after cranking/trying to start?
Suggest you:
Disconnect the exhaust at the manifold and try to start.
Hi,
Thank you very much for your time and the quick response.
1)I will check on the wiring harness issue.
2)Battery voltage is Ok. Replaced OVP relay for good measure.
3)Bleed Fuel distributor.
4)The plugs are wet after cranking.
Any chance the ECM could have gone bad? Any suggestions on how to test it?
Thanks,
Peter
AnswerWet spark plugs = excess fuel or no spark.
You need someone local for hands on help.
The ECM can go bad, especially if the incorrect ignition coil is installed.
My best advice:
If you are In the USA/Canada or UK, and can give me your geographic location, I will try to find a good MB shop near you. (other Nations are possible, but not as easy to locate independent service shops).
If you are outside those areas, I suggest you join:
http://www.mercedesshop.com/shopforum/index.php
and post your issues in both
Tech Help & SL Forum
I regret that I have not been able to resolve this issue.
