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May I seek the forums' expertise on the challenges I am experiencing with the first ignition of my '89 300CE in both low and high temperatures? I am not a professional mechanic, but I am a skilled amateur with expertise working on Jet tronic systems used in BMW motorcycles that I rebuild.


The automobile has been inoperative for around 6 months. I managed to start its engine and get it in motion around 2 weeks ago. Unfortunately, it stopped functioning as I was returning home (fortunately, right at my gate) and remained non-operational until this morning.

Prior to storage, the vehicle had a recurring problem with warm/hot restarts, which necessitated the replacement of the fuel pressure regulator and the pumps.



The symptoms are as follows: The car's engine spins over energetically but fails to ignite. Eventually, when the key is withdrawn from the start position, it makes an effort to ignite. Sometimes, it manages to ignite on one or two cylinders before making a popping sound and shutting off. (I suspect that the issue may be related to the crank sensor or a timing problem.)

After fully charging the battery overnight, I successfully started and ran the vehicle this morning. However, when I attempted to move it after allowing it to reach operating temperature, the engine stopped and now it refuses to start again.



The pumps and fuel pressure regulator are in new condition and are functioning well.

I have inspected the OVP relay by disassembling it and found it to be in excellent condition both inside and externally.

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

Spark plugs have been replaced.

A new distributor cap and rotor have been recently fitted.

Last night, I applied a little amount of WD40 to the wires of the crank sensor as a precaution against moisture.

Could someone provide me with a diagnostic procedure that may assist me in a) starting it up and b) resolving the problem of overheating upon restarting.

We welcome and value all ideas, suggestions, and views.

This situation is similar to when the points ignition system fails to get sufficient electrical power from the coil during the engine's starting process. However, when the ignition key is turned back slightly, there is enough power available without needing to engage the starter motor.

An indication of a malfunctioning CPS (crank position sensor) is the engine stopping when idling when it reaches a high temperature and not restarting until it has cooled down. Presumably, the same applies to a cam position sensor, but it is just necessary for the purpose of beginning.

Thank you for your response, GoodBoyCar. The vehicle was experiencing stalling issues when driving at moderate speeds, such as at crossroads. Therefore, it is logical and understandable.

What is the current state of the HT leads? Which make of distributor cap and rotor did you install?

I installed a Bosch distributor cap and rotor arm. I examined the HT leads of Bosch Spark plugs using an OHM metre and confirmed that they all meet the specified requirements.

Which plugs did you install? They have a dislike for ornate electrical connectors.Furthermore, have you inspected for any potential hoover leaks? It is essential that any leaking pipes or tiny diameter tubes do not allow the escape of hoover.Thoroughly clean all the fuses and inspect the battery connections to ensure they are clean and securely fastened. Perform maintenance on the Earth points by cleaning, greasing, and replacing them.Additionally, it would be beneficial to thoroughly clean the idle air control valve with carb cleaning. I recommend filling it with the cleaner and allowing it to soak overnight. This section indicates the specific position of the icv.

Thank you. I have placed an order for a Crank sensor, however I will also use the opportunity to clean the IVP while I am working on it.

Are there any loose connections in the fuel pump relay? The 2-stage starting and running components may be simply fixed or resoldered if the issue lies inside them. You can find instructional videos on YouTube that demonstrate how to do these repairs.