2003 Mercedes ML 270 CDI starting issues

[Johnnyquk16]

Hi Fellow Merc Buddys
Im in need off some of you vast knowledge i have a starting issue with my ml it can take up to 50 - 7- spins before it starts however once started it starts on the button every time until you leave it over night then it happens again.
There are no obvious leaks or smell of diesel
i have changed the the camshaft and crankshaft sensors when the car is running it pulls like a train no smoke of chuffing, EGR valve is nice and clean new air filter.

now for the weird bit if i park it on a slight slope overnight it starts ???? any ideas what it could be

Getting a bit fed up with it now please help

 

[91dm]

I had the same issue with mine at the start of winter a few years ago.

It will be the o-rings on the plastic fuel pipes. At the front of the engine, there is two pipes going into the primary pump on the right. Change these first of all and see if it is improved.

 

[wu56Shoozz]

Or the LP Diesl pump - the one that draws the fuel from the tank..

 

[91dm]

Sorry, should have said low pressure / lift pump. Just be careful when taking the pipe off, the plastic ends can be brittle. New pipes from Mercedes are around £15-25 each but you can just change the rubbers.

 

[estate-agent]

My old CLK 270 CDI had same issue with starting, turned out to be a perished fuel pipe up near the fuel filter, replaced the one that looked bad and all was good again.

.

 

[Johnnyquk16]

Hi thanks guys I'm going to have a good look at the weekend and change the o rings just for the lol's will let you know how i get on thanks for all the advice


one other question does the system need to be bleed if so any advice on how

 

[wu56Shoozz]

Change the O Rings for the green type they are a better than the black.. as the pipes are reasonably cheap I'd replace them as they do go brittle, I did that and haven't looked back and still have a set of spare seals just in case..

 

[Johnnyquk16]

started it yesterday fired up ok went for a long drive no drama's at all went to start it this morning it just spins over so i changed all the o rings for green ones from MB still no joy, no obvious leaks span it over for quiet a while...losing the will to live any other suggestions ;(

 

[Johnnyquk16]

Change the O Rings for the green type they are a better than the black.. as the pipes are reasonably cheap I'd replace them as they do go brittle, I did that and haven't looked back and still have a set of spare seals just in case..

started it yesterday fired up ok went for a long drive no drama's at all went to start it this morning it just spins over so i changed all the o rings for green ones from MB still no joy, no obvious leaks span it over for quiet a while...losing the will to live any other suggestions ;(

 

[91dm]

You changed the o-rings today? The fuel would have drained back once you let air in so would have took a lot of turning to start after changing the rings. You won't know until tomorrow if it's any better.

 

[mersum1es]

Is there air bubbles running in clear pipes? If yes, you still have a leak (these won't usually leak fuel out because suction type transfer pump, only aux pump and hp pump connection line is slightly pressurized). If no bubbles, do a injector leak back test. One Minute cranking (or run if it starts), should not leak more than 20ml.

 

[wu56Shoozz]

LP Pump by the sounds so of it... not drawing the fuel from the tank quick enough, don't keep cranking longer than 3 second or you'll collapse the HP pump as well and then your in a world of hurt.. ask me how I know.. common fault on Jeeps, so we break into the fuel line and fit an electric pump at the tank to push the fuel through and no further problems..

 

[a111r]

A well known MB Indy told me 2 sec of EasyStart is ideal.

 

[Johnnyquk16]

Just an update still issues with starting no air bubbles in the fuel lines the weird thing is it wouldnt start this morning after alot of turning so i left it for a few hours went back out tried again it started...this may be related to the none starting but when i drive it from cold it pulls like a train but when it warms up it gets very sluggish could it be the camshaft sensor or should i just put a hammer through it !!!!

 

[Johnnyquk16]

Hi again
Just put a new camshaft sensor on it still no joy when it gets up to temp i get loss of power when it s cold pulls like a train OMG pulling hair out as we speak

 

[91dm]

Doesn't seem to make much sense, no wonder you're pulling your hair out!

Usually poor starting / parking on a slope points towards air getting into the pipes.

Have you had it plugged in anywhere, any codes for the rail on the sensor?

 

[Johnnyquk16]

Hi i got it plugged in and it came back as maf sensor so i changed that....and guess what it didnt work still same problem it gets to temperature still sluggish not sure if it will start in the morning as i have only just put it in...is there another sensor on the rail???

 

[brucemillar]

Hi i got it plugged in and it came back as maf sensor so i changed that....and guess what it didnt work still same problem it gets to temperature still sluggish not sure if it will start in the morning as i have only just put it in...is there another sensor on the rail???

If it is still saying the MAF Sensor? check for intake leaks and also check the loom to the sensor. Use a can of Damp Start and spray it up the intake hoses (assuming you can get it to run) if the revs flare it is sucking in air/damp start at that point you were squirting. If it fires up when squirting and cranking (you need two people) then the same thing. It is sucking in air/damp start and you have split pipe in the intake side. I do not now these engines so can't be very specific, but this is "usually" a good test for vacuum leaks.