C-Class (W202) 1995-2000: C 200 CDI, C 220 CDI, C 270 CDI, C 180, C 200 K,C 230 K, C 220, C230, C 280

Ignition wiring question

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Old Apr 13, 2025 | 07:31 PM
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1993 C180 (W202)
Ignition wiring question

I've been trying to put this old merc of mine back on the road after it was stood for about 7 years. Turns fine but won't start.
Replaced the spark plugs, fuel filter and pump. Knew the car was left with around 30L of old E10 petrol inside so I tried to drain it at the sender unit check valve. Surprisngly nothing came out so I added around 10-20L of E5.

Still the engine refuses to start.

After flushing the fuel rails with alcohol I notice that the copper wires on the injector connectors were clearly visible. A quick continuity check shows 2 out of the 4 cables are shorting.
I've seen online that these mercs suffered from "biodegradable wiring" which would disintegrate when exposed to the high temperatures of an engine bay. However, I have absolutely no idea how widespread this problem is and some insight would be greatly appreciated.

My biggest question is whether I should reinsulate the individual injector wires in situ and do my best not to disturb the rest of the wiring harness, or rip the whole thing out and reinsulate every wire (I have already tried removing the wiring harness but it's caught somewhere I cant access so I'd have to cut several wires. A similar story with the throttle body - I cant for the life of me figure out how to unplug that connector underneath the inlet manifold).

Has anyone else had to deal with similar problems with their merc?




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