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Assistance needed in identifying starting problems with '89 300CE M103.

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I would want to seek advice from the forums on the difficulties I am experiencing with starting my '89 300CE in both cold and hot conditions. I am not a professional technician, but I am a good amateur with expertise working on Jet tronic systems from BMW motorcycles that I rebuild.

The automobile was inactive for around 6 months. I managed to start and move it about 2 weeks ago, but it stuck on the way home and just restarted this morning.

The warm/hot startup problem existed prior to storage, prompting the replacement of the fuel pressure regulator and pumps.


The symptoms include a car that spins over energetically but fails to start. When the key is withdrawn from the start position, the engine tries to start, sometimes firing on one or two cylinders before stalling abruptly. (I suspect a potential issue with the crank sensor or timing being wrong)

After fully charging the battery overnight, I successfully started and ran the vehicle this morning. However, after allowing it to idle till reaching operating temperature, it stuck when I attempted to move it and now it would not begin.


The pumps and fuel pressure regulator are new and functioning well during priming.

I have inspected the OVP relay by removing and opening it, and found it to be in excellent condition inside and externally.

I have inspected the EZL and distributor contacts and confirmed they are free of dirt and moisture.

Spark plugs replaced.

Recently fitted a new distributor cap and rotor.

Applied WD40 to the crank sensor cables yesterday night as a precaution against moisture.

Can someone provide me with a diagnostic method to assist me start the system and fix the hot restart problem?

All views, comments, and opinions are welcomed and valued.

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It reminds me of a situation where the coil doesn't get sufficient power when cranking, but when the key is turned back slightly, there is enough power without needing to engage the starting motor.
A sign of a malfunctioning CPS (crank position sensor) is the engine stopping while idling after reaching operating temperature and not restarting until it has cooled down. The cam position sensor is likely the same, although it is only necessary during the beginning process.

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I installed a Bosch distributor cap and rotor arm. I inspected the HT leads using an OHM metre and found them all to be within specifications, along with Bosch spark plugs.


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Which plugs did you install? They dislike elaborate plugs.Have you also inspected for hoover leaks? Leaking pipes or tiny bore tubes must not leak under vacuum conditions.Clean all the fuses and inspect the battery terminals for cleanliness and tightness. Clean and lubricate the Earth points, then reinstall them.Additionally, it is recommended to clean the idle air control valve thoroughly with carburetor cleaner. I fill mine with the cleaner and let it set overnight. This is the location of the intracranial volume (ICV).

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Are there dry joints in the fuel pump relay? The two-stage starting and running components may be readily fixed or resoldered if necessary. Refer to YouTube for instructional videos on how to do this.


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