merc C250 diesel fuel delivery from tank

[charliefarlie]

Have a problem with my merc C250 diesel estate S reg hasnt done lots of miles only 122thou , have started working on it to see if can find the problem of it not starting, its not electrical as have tested all that , its just not getting fuel , what i would like to know if this model has an electric pump in the fuel tank or is it a sucking mechanical type from the injector pump .
Any help would be great . thanks cf

 

[Dieselman]

The mechanical lift pump is mounted on the side of the main injection pump.

 

[charliefarlie]

Thanks dieselman
One thing have noticed on this engine , how awkward it is to get at or replace the heater plugs , unlike my sprinter a piece of cake plus easy peasy to get at anything loads of room, it too is a 5 pot diesel

 

[Dieselman]

You have to remove the intake manifold, after that it's easy.

 

[charliefarlie]

Thanks for that Dieselman , did have a look at the inlet manifold and no doubt will have gaskits to replace hence why left it in position not wishing to disturb it so to speek , the mechanical lift pump which side is it on the main injection pump .
many thanks cf

 

[Dieselman]

The manifold has rubber O rings at the joints, the lift pump is on the n/s of the injection pump, you can't miss it.

I really can't see the lift pump being the problem, much more likely is an air leak.

 

[charliefarlie]

Many thanks Dieselman , the car has been no problem at all started up went every where returned 50 plus to gallon faultless then when the first frost came i noticed it was difficult to start , it would start then imeadiately stop , i went through the proceedure to restart it and it eventually started after much turning of the engine more than usual , it never did it again till this past weekend when we had minus6 , it started then stopped and would not fire up at all dead meat, engine turns ok but not a chunter , dont know much of it recent past services apart from it not haveing an oil filter and oil change till i did it last week it was in dire need of it as the oil in it was very black and thick with it , now has the synthetic oil in it as recomended plus nice new filter , bought a new battery for it today as recomended for the car its twice the size of the one thats in it , tomorrow am intending to replace the fuel filter as suspect it hasnt been done for a good while , if its drawing air i presume it will be off those clear plastic pipes that run here their and every where ? many thanks cf

 

[trapperjohn]

I'm not sure and DM will correct me if I am wrong but you could have a problem with the pre-fuel filter being blocked. On my 300Ds this sits under a bolt head (10mm?) right next to the main fuel filter. These can be over looked when changing the main fuel filter.

 

[Dieselman]

^ it could be, which will exacerbate any air leak, but the fault sounds typical for an air leak.
the engine starts on the fuel held in the IP then draws air so stops.

 

[charliefarlie]

Thanks for that John,will have a gander tomorrow am pretty sure it cant be a lot wrong with it as went perfect before that blinking freezeing weather turned up , much nicer now milder with it . cf

 

[charliefarlie]

Thanks 2 you both for your help is now cured , put a new fuel filter in it this morning also put the proper battery in it , i removed the pre fuel filter it was clogged with muck cleaned it with petrol and gave it a blowing over with airline got it all nice and clean again and resembled it all , glad to report all works perfectly again many thanks . have a great xmas and New year CF

 

[SilverSaloon]

Thanks 2 you both for your help is now cured , put a new fuel filter in it this morning also put the proper battery in it , i removed the pre fuel filter it was clogged with muck cleaned it with petrol and gave it a blowing over with airline got it all nice and clean again and resembled it all , glad to report all works perfectly again many thanks . have a great xmas and New year CF

if the prefilter is clogged, then i'd also recommend cleaning out the in-tank strainer. its basically a bigger version of the pre-filter. if the prefilter is clogged, then i suspect the strainer will be too. worth doing

 

[charliefarlie]

Thanks for that ss, can this strainer be easily located , dont have a work shop manual for the car so am working blind .
CF