I have a euro built 1980 500 SEL. It cold starts dependably. However it often refuses to start warm...just cranks and cranks. Once it cools off it starts again fine. Whats wrong with this picture?

 

you have a bad ignition control module i have replaced quite a few of them (15-20) there quite expensive. but to diagnosis it correctly you must first check your fuel pressure.

 

I once had the same problem in my 1985 380se. The fuel systems are very close. For me it was the fuel accumulator. An easy way to check for a loss of fuel pressure is to depress the AFM flap. If it gives resistance then the pressures holding, if not then there's your problem. It could be a FPR, accumulator, or a leak in the lines along the way.

-Troy

 

Thanks for the help..Ill begin the elimination process.