Fuel Pump or Fuel Filter?
Thread Starter
Junior Member
Joined: Jun 2009
Posts: 52
Likes: 0
From: Hong Kong
2001 E240
Fuel Pump or Fuel Filter?
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.
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.
Senior Member
Joined: Nov 2004
Posts: 391
Likes: 0
From: San Jose, CA
2000 E430 Sport
I had this problem before
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
http://www.benzworld.org/forums/w210...-pictures.html
Thread Starter
Junior Member
Joined: Jun 2009
Posts: 52
Likes: 0
From: Hong Kong
2001 E240
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.
Last edited by Perrier; Jan 9, 2011 at 02:22 AM.
MBWorld Fanatic!
Joined: May 2008
Posts: 1,072
Likes: 5
From: Pittsburgh,PA, Cambridge, Ontario, CN
2003 S210 3.8L Brabus wagon
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.
