CLS (E class) in tank pump issue

Mr Hatt

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Your Mercedes
E320CDI Sport S211 2009, CLS320cdi Sport C219 2006, CLK320 Cab W209 2005
Hi all hope everyone had a lovely Christmas or at least one that was slightly smoother than my own, after last minute shopping on Christmas eve I broke down on the way home, felt very much like the car had run out of fuel although I showed over half a tank full ?
Had the car recovered with a view to looking at it today and after scanning I had P0087 low fuel pressure at rail so looks like I did run out of fuel, filter in engine bay had no supply but in tank pump was running ?
Decided to start at the tank working forward and having removed the two covers from each side of the tank under the rear seat I found the pump fully submerged in a full tank on the driver side, imagine my surprise to find the other side with the fuel supply and return pipe completely empty!

I realise that replacement parts need ordering but can anyone with experience explain how this fuel transfer from one side to the other works or in my case does not.

This is a CLS320 cdi with OM642 v6
 

V6Matty

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S212/2010/E350 (His) W246/2016/B200 (Hers)
Known as saddle tank syndrome and not often seen on the 219, there is a baffle that fails and stops the fuel averaging between the two side of the tank.
Afraid I haven’t a clue how to fix it but I have heard there are ways but the best way is new tank :(
 
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Mr Hatt

Mr Hatt

Senior Member
Joined
Sep 14, 2015
Messages
358
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Location
Lincolnshire UK
Your Mercedes
E320CDI Sport S211 2009, CLS320cdi Sport C219 2006, CLK320 Cab W209 2005
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Known as saddle tank syndrome and not often seen on the 219, there is a baffle that fails and stops the fuel averaging between the two side of the tank.
Afraid I haven’t a clue how to fix it but I have heard there are ways but the best way is new tank :(
Hi Matty glad to see your still on here, I have not been on for a while, Well your right but I am going to have to start a new post because I have it all wrong, because I was so focused on saddle tank syndrome, after reading about it some years ago when I opened the covers and saw fuel only in one side I congratulated myself on my vast knowledge picked up on the forum over the years. Heres the thing I just realised, all my fuel is in the pump side and although the outlet pipes are on the other (empty) side they run from pump and through tank to there so actually the fuel is in the correct place if I am only half full and I have another issue, sorry to everyone for that rookie mistake and I am off to the other end to see if I fair better under the bonnet.
By the way the fuel tank replacement model is the 350 blue tech model with only one cover and outlet, glad it is not that kind regards Steve
 

V6Matty

Senior Member
Joined
Aug 1, 2012
Messages
9,354
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4,204
Location
Newark, Nottinghamshire
Your Mercedes
S212/2010/E350 (His) W246/2016/B200 (Hers)
Hi Matty glad to see your still on here, I have not been on for a while, Well your right but I am going to have to start a new post because I have it all wrong, because I was so focused on saddle tank syndrome, after reading about it some years ago when I opened the covers and saw fuel only in one side I congratulated myself on my vast knowledge picked up on the forum over the years. Heres the thing I just realised, all my fuel is in the pump side and although the outlet pipes are on the other (empty) side they run from pump and through tank to there so actually the fuel is in the correct place if I am only half full and I have another issue, sorry to everyone for that rookie mistake and I am off to the other end to see if I fair better under the bonnet.
By the way the fuel tank replacement model is the 350 blue tech model with only one cover and outlet, glad it is not that kind regards Steve
Ah well that changes things a bit ;),
In that case yes I guess you are back looking at pump issue, or maybe a blockage on the return side which is then giving incorrect readings?

yep, still here, even when I went a bit made for a while with the Pug I came back after just a couple of years and back in an S212 bought from a fellow member here
 
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Mr Hatt

Mr Hatt

Senior Member
Joined
Sep 14, 2015
Messages
358
Reaction score
82
Location
Lincolnshire UK
Your Mercedes
E320CDI Sport S211 2009, CLS320cdi Sport C219 2006, CLK320 Cab W209 2005
  • Thread Starter
  • Thread starter
  • #5
Ah well that changes things a bit ;),
In that case yes I guess you are back looking at pump issue, or maybe a blockage on the return side which is then giving incorrect readings?

yep, still here, even when I went a bit made for a while with the Pug I came back after just a couple of years and back in an S212 bought from a fellow member here
You and me both fela, I bought a mk7 golf gti for a while and came back when I found a Cat N CLS, whilst repairing it, it grew on me and the rest is history, if you look at the new thread regarding the fault codes and the work I did today I now have a successful conclusion, thank the stars regards Steve
 


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