w124 om605 problem with vacuum fuel pump

Theor

New Member
Joined
Dec 23, 2019
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Rugby
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w124 2.5D
hello guys, I am new in the club but always on MB :)
I bought last summer a beautiful w124 2.5 diesel non-turbo manual from 1994 with om605.
a few weeks ago had ward start, especially when was cold, took about 8-10 sec, last few days after 2-3 tries and now she is dead.
sent to mechanic, he checks most of things and told me it should be an electric problem, he called an electrician he checked again but didn't find anything wrong. but still the fuel pump not supply diesel at all.
we change the fuel pump relay and the overvoltage, still the same.
he tried to connect the fuel pump straight to the battery but the pressure was very low.
also, I discover allot of water inside in the car, especially mats was completely wet, we check the seals underneath but everything looks fine, doesn't have a sunroof.
another thing, the previous owner used it with veg oil but microfiltered so don't know if this really matters.
any suggestion about it? also can I fit a mechanical fuel pump to solve this issue?
thanks
 
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Theor

New Member
Joined
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Location
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w124 2.5D
hi again and happy Christmas :D
Just checked the car and also came to my mind that the central locking is not fully working from that day when u lock it everything works fine and you hear a sound for about 30 secs( not sure if this is right) when u try to unlock it just open the driver door.
I saw that they are few cables colored grey and brown/blue connected to the vacuum pump and wondering if they related with the central locking system.
any idea?
thanks 80210811_3749672921712086_2672566266341883904_n.jpg 80746957_799755273863353_4356324262487785472_n.jpg
 

a111r

MB Enthusiast
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S123 240TD, S210 320cdi, S202 250TD.
This engine doesn't have an electric fuel pump, only a mechanical lift pump.

The issue here will be the one or more of the 13 O rings having gone bad, allowing air to be drawn in. Common issue with the 606 and 605.
BTW, I can supply them all, quite cheaply.
 

grober

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http://www.w124-zone.com/downloads/MB CD/W124/w124CD1/Program/Engine/605_606/07.1-0005.pdf
VACUUM DIAGRAMS- The engine associated vacuum comes from a mechanically driven pump on the front of the engine. THE CENTRAL LOCKING from an electrically driven pump beneath the rear seat. Internal water leaks often come from blocked black plastic drain channels at either end of the front bulkhead inside the engine compartment
see
Model 124 Maintenance Manual Index
and this thread
1992 W124 diesel will not stop running off the key
 
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Theor

New Member
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w124 2.5D
thank you a111r!
I feel silly as the mechanic who checked the car, told me is electromechanical pump as send/receive an electric pulse to cut off and open it.
the pump is dry, can be an internal leakage? can be checked from fuel tank lines?
if this gonna be the problem I will need the rings to give it a trial :)
grober thnk you for the manuals, they opened a whole new world to me :)
 

a111r

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S123 240TD, S210 320cdi, S202 250TD.
Sack that mechanic, this is basic 1980's MB engineering.

If it's been vegged, remove and clean the in tank strainer first, an easy DIY job.
Then change all the 13 O rings.
 
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Theor

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w124 2.5D
hello again
after replacement of O rings the problem still here, the engine cranking but don't start...
also, I saw OPV fuse was gone, I replace the OPV with new one but still doesn't start, this makes me wanter if its some electrical problem, with it.
what kind of electrics they use this pumps? If I will replace it with mechanical one would be fine?
 

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