Help diagnosing start issues '89 300CE M103

[Hank the Tank]

Could I press on the forums wisdom regarding issues I am having with both cold and hot starting on my '89 300CE. I am not a professional mechanic but reasonably competent amateur with some experience of Jet tronic systems from BMW bikes which I restore.


The car has been laid up for about 6 months and I got it started and moving about 2 weeks ago unfortunately it stalled coming home (luckily right at my gate) and would not restart until this morning.

The warm/hot restart issue was there before laying it up and that was the reason for changing the fuel pressure regulator and the Pumps.



The symptoms:
Car turns over very lively but does not fire, eventually when the key is released from the start position it attempts to fire, sometimes catching on one or two cylinders before popping and dying. (This has me thinking Crank sensor/Timing off)

After giving the battery good charge overnight I actually got it starting and running this morning, after letting it idle up to temperature I tried to move it but it stalled and will not restart.



The pumps and fuel Pressure regulator are new and priming/puming ok.

I have removed and opened the OVP relay to check it and it is in good condition inside and out.

I have checked the EZL and distributor contacts are clean and dry.

Spark plugs changed.

New distributor cap and rotor installed recently.

Sprayed a bit of WD40 on the crank sensor wires last night in case of dampness.

Can anybody point me at a diagnostic process that can help me a) get it running and b) resolve the hot restart issue.

All thoughts, inputs and opinions considered and appreciated.

 

[Bellow]

The symptoms:
Car turns over very lively but does not fire, eventually when the key is released from the start position it attempts to fire, sometimes catching on one or two cylinders before popping and dying. (This has me thinking Crank sensor/Timing off)

That's reminiscent of points ignition when the coil doesn't quite get enough juice during cranking but when the key is rolled back there's enough without having to turn the starter motor.

After giving the battery good charge overnight I actually got it starting and running this morning, after letting it idle up to temperature I tried to move it but it stalled and will not restart.

Symptom of a failing CPS (crank position sensor) is stalling at idle when warm and refusing to re-start until it has cooled off. Presumably the same for a cam position sensor - but it is only needed for starting.

 

[Hank the Tank]

Thanks for the reply Bellow. The car was also stalling on the road at lower speeds (junctions etc.). So that makes sense

 

[carat 3.6]

What condition are the HT leads in? Which brand of cap and rotor did you fit?

 

[Hank the Tank]

What condition are the HT leads in? Which brand of cap and rotor did you fit?

I fitted a Bosch cap and Rotor arm. Bosch Spark plugs and I tested the HT leads with and OHM meter and found them all to be in spec.

 

[optimusprime]

What plugs did you fit ? they dont like fancy plugs .Also did you check for vacuum leaks? any l;eaking pipes or small bore tubes must not leakl vacuum .Clean all the fuses up, and check if the battery terminals are nice and clean and tight . Earth points - clean them up and grease and replace them /Also the idle air control valve could do with a good clean out with carb cleaner..i fill mine up and let it sit over night . This is the part - this is the location of the icv

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[Hank the Tank]

What plugs did you fit ? they dont like fancy plugs .Also did you check for vacuum leaks? any l;eaking pipes or small bore tubes must not leakl vacuum .Clean all the fuses up, and check if the battery terminals are nice and clean and tight . Earth points - clean them up and grease and replace them /Also the idle air control valve could do with a good clean out with carb cleaner..i fill mine up and let it sit over night . This is the part - this is the location of the icv

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Thanks optimusprime. I have order a Crank sensor but I’ll certainly give the IVP a clean whilst I’m in there.

 

[grober]

DRY JOINTS in fuel pump relay? its 2 stage starting and running they can be repaired/resoldered easily if its that - see youtube for video how--to's

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[optimusprime]

Need yo know what plug types were used in this engine ,,,,you never said