+1 for an odd issue and having the car scanned. Even though you don't see any warning lights on the instrument cluster there can still be error codes stored in the car's memory. Several auto parts places do this for free or for about $50 you can buy a decent one. Actron is a frequently recommended brand.
"Classic description of a fuel pump relay. Very common in the W126 Section."
Thank you VERY much for all of your kind attention and recommendations. I should have mentioned that I have done quite a bit of wrenching over the past 50 years and after the first failure, I really
strated to take note of all (emphasis added) symptoms, including preceeding and post-problem.
Also, when it finally re-starts it is absolutely instant, first touch of the key, first revolution of the engine. No rough running. No indication of lines refilling with fuel. Either runs perfect or dead, no in-between
Actually closed my eyes in a quiet location with all the windows open, started it and just 'listened and felt' while it quit.
I kind of ruled out a fuel problem any real distance from the injectors / injector pump as there was/is absolutely
no 'stuttering' or 'partial catching' of the engine during unsuccessful cranking. There is also no backfiring, jerking or even the slightest
indication of poor running before quiting, or upon restarting, (such as I would think would be the case as an injector pump picks up the remaining drops of fuel in a line going dry, or re-fills). Shuts off like a switch.
PLEASE correct me if this engine/fuel system has a feature on it that would overide this speculation.
I have ordered yesterday afternoon - 3:00 PM, (and received at 10:00am this morning ((!!!!!!)) ) a Crankcase Position Sensor, for $113. from PRIME MOTOR GROUP (highly
recomended and Mercedes Factory Authorized).
I am going to attempt
to install this sensor and will report the results back to the Board.
I have heard rumors of a special "adjustment" or "set up" routine required to get a newly installed CPS to function, but am UNABLE to get any solid details. Any knowledge of a "post-installation procedure" please ??
I really appreciate all of your attention and ideas. A great group.
Thank you. Thomas