C270 cdi not starting

[Gixxerguy]

Sorry for the long message before hand
Hi folks, desperate measures now.
Same old question so here goes,
My c270 cdi turns over, won’t fire unless I spray deodorant up the intake and then runs perfect afterwards until you turn it off then try to rest start it straight after and the same happens again.
I have replaced all fuel lines from filter forwards and all o-rings have been replaced, new cam and crank sensors fitted, HP pump has been rebuilt with all new seals and o-rings, there are no air bubbles in the lines anywhere at all and I’ve even fitted a non return valve straight after the fuel filter so it holds the pressure in the lines engine side.
I’m getting to the end of my tether with it now.
Something I read said that the in tank fuel pump should prime but I can’t hear anything when I turn the ignition on! Could that be the cause?
For it not to start straight after turning it off leads me to believe it is something so stupid but I’m at my wits end.
Any help or ideas would be greatly appreciated,
Thank in advance

 

[Gixxerguy]

Sorry for the long message before hand
Hi folks, desperate measures now.
Same old question so here goes,
My c270 cdi turns over, won’t fire unless I spray deodorant up the intake and then runs perfect afterwards until you turn it off then try to rest start it straight after and the same happens again.
I have replaced all fuel lines from filter forwards and all o-rings have been replaced, new cam and crank sensors fitted, HP pump has been rebuilt with all new seals and o-rings, there are no air bubbles in the lines anywhere at all and I’ve even fitted a non return valve straight after the fuel filter so it holds the pressure in the lines engine side.
I’m getting to the end of my tether with it now.
Something I read said that the in tank fuel pump should prime but I can’t hear anything when I turn the ignition on! Could that be the cause?
For it not to start straight after turning it off leads me to believe it is something so stupid but I’m at my wits end.
Any help or ideas would be greatly appreciated,
Thank in advance

 

[Mark A]

Have you checked the lines from the tank to the filter. I had a similar problem on our old W163 ml-270, after taking off the under trays I found a leak about halfway along the passenger side.

 

[Rory]

In the absence of other replies - sorry, I'm not very practical but I'm not aware of any other pump in mine although maybe older models had a lift pump, what year is yours?

It still sounds like there's a fuel pressure problem. Is the battery / starter turning it over at a good speed? The standard advice is to get it to an indie with the Star diagnosis tools otherwise you're just doing what you've done and replacing lots of parts hoping to hit the riht thing. On an older car, of course, it's always possible that there's lots of little things wrong which individually you'd get away with but collectively conspire to stop the car starting.

 

[Gixxerguy]

I’ve tried everything I could possibly try, the main thing that makes me wonder that it’s something stupid is the fact I can leave it ticking over for over an hour, turn the engine off, straight away, try to restart it and it won’t fire up again, no matter how long I try!

 

[mersum1es]

Primer pump in tank became later models, I can't remember when...

non return valve is large enough (you may actually worsen suction, because there is now extra flow resistance)?

Have you measured rail pressure in cranking? That is most likely the issue, but just make it 100% sure... you have not measured injector tankl ine leaks? That's 2nd - to do - after return line o rings. Those lines can actually brittle too, bbut if no air bubbles, it should be ok (other possible leaks are on fuel filter black rubber lines, fuel filter housing/cap if this model has plastic housing, pressure regulator o-ring). But start with injector leak test!

 

[M80]

Excessive injector leak off?

 

[ants-uk]

Hi Gixxerguy,

Have you made any progress on this? I have exactly the same issue. The car, ML 270 CDI W163, can be on the driveway for a night, a week, a month....and start first time. But after a short spell of warming her up, she won't start....or might reluctantly start. I have to wait 2 hours before she starts first time (have you tried that test?)

So, my first thoughts, based on the two hour required rest needed, is that something is resetting. Maybe something has to cool, or air has to leave something or fuel has to replenish something? Before I make my own post with these observations, I was wondering what progress you had made with this very frustrating issue.

Hopefully later today, I'll monitor the drag on the battery between a cold start and a warm start to see if there's a difference.

 

[M80]

Hi Gixxerguy,

Have you made any progress on this? I have exactly the same issue. The car, ML 270 CDI W163, can be on the driveway for a night, a week, a month....and start first time. But after a short spell of warming her up, she won't start....or might reluctantly start. I have to wait 2 hours before she starts first time (have you tried that test?)

So, my first thoughts, based on the two hour required rest needed, is that something is resetting. Maybe something has to cool, or air has to leave something or fuel has to replenish something? Before I make my own post with these observations, I was wondering what progress you had made with this very frustrating issue.

Hopefully later today, I'll monitor the drag on the battery between a cold start and a warm start to see if there's a difference.

Will it run when started, or cut out after a while?
Cutting out due to warming up is commonly the Crankshaft Position Sensor.

Getting the fault codes read would be useful, but the CPS isn't generally expensive.

 

[ants-uk]

Will it run when started, or cut out after a while?
Cutting out due to warming up is commonly the Crankshaft Position Sensor.

Getting the fault codes read would be useful, but the CPS isn't generally expensive.

Hi M80, the car runs just fine and idles just fine once started. I ran the fault codes last night, recorded the results, reset them and re-ran the test with fewer fault codes coming up. I will run them again after taking her out for a little drive. I haven't had time to look into the fault codes recorded but will do this weekend.