So this random long cranking keeps driving me nuts.
Have changed a lot of parts but this "slow starting" is still there.

I am finally convinced either the fuel pump or fuel filter that I already changed a year ago must be changed again.

Since this long cranking does only when engine is warm, I am more inclined to change out the fuel pump.

If the fuel filter (the fuel pressure regulator is integrated in that) is faulty, then the long cranking should do while engine is cold as well.

My car runs extremely smooth and there is none of that rough idling, stall, hesitation, and hissing sound, so I have ruled out the MAF, vac leaks, EGR and leaky injectors.

Also if I wait at pos 2 before turning key to pos 3 - the long cranking never does so I have ruled out the CKP and CPS and EIS and K40. If they are bad, waiting at pos 2 won't do any good.


This long cranking is so erratic that my mechanic is unable to gauge the fuel pressure while car is in his shop.

Did I overlook anything?

The fuel pump that I changed last year is a brand new original Mercedes part, and to have this changed again in less than 1 year is not easy to swallow.

I'd start cheap and do the fuel filter first.

Change your Crank position sensor. Mine wouldn't start when engine was hot. I had to wait for the car to cool down to start. A couple of days later it turned off while I was doing 65mph on freeway. I'm sure you don't use cheap gas, I always use Super Unleaded.

http://www.benzworld.org/forums/w210...-pictures.html

What else can you think of as the culprit...?.. bearing in mind that if I wait at pos 2 for a few seconds, the random long cranking can be eliminated.

Take it somewhere and have them read the codes. Then you won't have to keep guessing

Agree w/ above however I would bet the CPS is bad. It's only 40$ and easy to change out. went through the same thing at last years Pittsburgh Vintage Grand Prix. B Rahal motors diagnosed it and they were right on. Was able to leave the golf course after cool down and changed it at home. Problem resolved and has not reappeared.

No codes... all perfect