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1985 500SEL
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835 Posts
Discussion Starter · #1 ·
Update...
1985 500SEL

My friend looked at my car in my garage today
we found that the fuel pump is not buzzing and there were no sparks from the wire from the distributor...

we looked at the wiring diagrams and he said it could be two things

the Ignition control unit(80%) or the distributor(20%)..


what you think

should I take a chance and buy an ignition control unit????Do these things usually go on these cars??

please shed as many comments as you can..

Thanks a lot...
 

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I had a ign module go but that's not the way to analyze what's wrong with a car. Jumper the fuel pump relay, the pump will start. If it doesn't that is the first problenm to take care of. If it does start then check for spark. If no spark at distributor center lead then check the ign module AND coil/resistors. I had a coil short.
 

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1985 500SEL
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835 Posts
Discussion Starter · #3 ·
can you please tell me how to jumper the Fuel Pump relay

I found it with 7 pins under my fuse box

but I have no idea how to jumper it..

please advise
 

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1985 500SEL
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835 Posts
Discussion Starter · #5 ·
Update...

I have jumpered the Relay and I got the pump to work... but the car wont start, there is no spark

so what you guys think

I am leaning towards the Ignition Control module, because when I was cranking the car with the relay on I was getting no spark and the pump was not on....

and I looked at the wiring diagram, and the Ignition control module connects to the fuel pump relay...

so in other words.. the Control module is not giving spark or fuel..

does my diagnosis make sence??

Thanks
 

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1985 500SEL
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835 Posts
Discussion Starter · #7 ·
The ignition control unit is a small silver box on the driver's side under the hood closer to the front head light and is mounted with three bolts under the hood


I got a non Bosh unit.. that is manufactured in germany and it works great, looks different from original
 

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'92 300SE, 203k
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36 Posts
Does it have a security immobiliser? This could have failed and is cutting off both things 'upstream' if you see what I mean?
 
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