Hi, New to the "Mercedes Benz Thing" and loving it!
I recently bought a 51 plate 320CDI, which has done 200,000, but is a lovely car well looked after, 1 owner, fsh, etc, although it had had a starting problem just prior to me buying it which "seemed to have been fixed".
In the time I have had the car (3 months) it has now become apparent where the problem lies....The fuel system does not remain "charged" and for some reason the fuel filter housing emptys after a few days with no signs of leaks and this is when I have starting trouble, if I fill the housing with fuel, its starts! and runs ok for a few days but then it starts strugling to start again, so i have to fill housing again.
I assume this should stay full,(or should it?) Maybe it is dropping back? but I dont know why it emptys!
Prior to discovering this I was using Easy Start for a couple of weeks and it would start every time and runs superb and drives fine, plenty of power etc, but the fuel housing was still empty! so I can only assume that it is being sucked almost directly across between the inlet and outlet pipes on the top of the housing, so this leads me to think that it is not a blockage in the pipe.
So I wonder is the fuel "pumped" prior to the filter? or is it "sucked" by high pressure pump at front of engine?
I have disconected fuel lines from top of housing (inlet and return) and found nothing comes out with the ignition on, or when cranking the engine.
I had it serviced recently (200,000) Mercedes Approved Repairer, and they couldnt diagnose any particular problem, but quickly told me that if I had further problems they would want it for a week, to run checks order respective parts and then check again over a couple of days, which is all very nice but I dont fancy the bill much!
Anyway hoped one of you guys may be able to shed some light on this for me as Im flumaxed!
Thanks a lot, Ray.
( p.s when I say empty above, there is about 30mm depth of fuel in bottom of housing, Thanks again.)
Welcome to the forum. Fill up your model and location when you have a chance.
Unfortunately diesel owners are minority here and with 320 you might be alone having problems.
So to start, diesel lines leaks are different than gasoline lines. When gasoline is pumped under the pressure from the tank primary pump, diesel is sucked from the tank by the pump mounted on the engine. So leaks on diesel lines show as air bubbles in the fuel.
I am not familiar with your engine, but older models have priming pump mounted at the bottom of the engine, than the fuel goes thru the filters and go to the injector pump.
At your mileage replacing o-rings might be in order. This is common issue on older engines.
Welcome to the forum. Fill up your model and location when you have a chance.
Unfortunately diesel owners are minority here and with 320 you might be alone having problems.
So to start, diesel lines leaks are different than gasoline lines. When gasoline is pumped under the pressure from the tank primary pump, diesel is sucked from the tank by the pump mounted on the engine. So leaks on diesel lines show as air bubbles in the fuel.
I am not familiar with your engine, but older models have priming pump mounted at the bottom of the engine, than the fuel goes thru the filters and go to the injector pump.
At your mileage replacing o-rings might be in order. This is common issue on older engines.
Hi, Thanks for your reply, fuel lines after the fuel filter housing are clear and we have watched these closely whilst engine is running and there are no signs of bubbles at all.
Once it is running it is fine no hesitation,lack of performance..nothing!
There is also no evidence of leaks anywhere underneath or around engine/fittings etc, from what you have said it may point towards the pump, not doing its job!
When you see "filter housing emptys" that's a sign of leak. The air has to enter the system somewhere. The best recommendation I could give you is buy set of o-rings for filter and the lines around and replace them. It is consider maintenance issue at this mileage. Just like spark-plugs on gasser.
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E320 CDI starting problems,Fuel shortage? 
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