poleman

Hello everybody

I am facing the following problem, which arleady 2 Mercedes dealer workshops have been unable to solve: In the morning when I turn the engine on to go to work, everything is normal and the engine fires-up in less than 2 seconds. However, when i drive for a while, say 10-20 miles and then stop/park , and leave the car for 5 minutes or more, when i get back to turn on the engine it needs at least 5-8 seconds of starter motor use to get fired-up again. However, if I leave the car for over 4-5 hours (or overnight), then the engine fires-up immediately . U can imagine that on busy days with the car , my battery gets exhausted by using so much of its energy for the starter motor. This has come to a point that is embarassing, as nearby people turn their heads when they listen to this prolonged starter motor use, obviously to see which is the car that rin out of petrol !!
Lastly please note that i have changed fuel filter twice and the tank is more than half full, so the reasons dont lye there..

Any help welcome. Thanks

Nosmo SL55

My immediate thoughts are crank position sensor. Do a search on this topic and see if your symptoms match others who have diagnosed the CPS as the issue.

poleman

thank you Nosmo . Unfortunately i ve had this changed about 6 months ago, as the car would not start at all when warm. after the change , the car would start , perfectly normal in the mornings , but with a lot of starter motor in between drives.. i am not a mechanic, but is there any way the MB dealer to had it installed incorrectly ??

MarkDnr

I have been experiencing this exact same problem with a VW. Fuel pump, Fuel Injectors are fairly new, Fuel Regulators are functioning and Coolant Temperature Sensor was replaced.. twice. No VW Mechanic has been able to figure out what the problem is. They all had one thing in common, those dollar signs in their eyes.

cyglee

A post on a Porsche 911 forum reported replacing the fuel pressure sensor for fuel tank solved their similar problem.