270 CDI/OM612 gurus please help! At the end of my tether! 270 CDI fuel pressure issues, tried almost everything no joy! Any help appreciated :)

[smanderson117]

Hello all, as title says I am about to lose it with my CLK 270 CDI om612 (2005). Backstory:

I had intermittent cutting out when giving it some and code P0251 injection pump metering control. It would cut out but a restart would fix it and clear code and off I went. Did this for 2 months until I got stranded on the motorway as car would restart but any load would kill it again. Changed fuel pressure regulator (theres a regulator/valve at the back end of the rail and a sensor at front of the rail and all seemed fine, easy fix I thought! It then started developing same symptoms again and also cranking was starting to take a while, especially when the car is warm. It still cuts out but it seems to be when you're foot the floor gunning it and only when it gets above 3.4/4k so when the car is really under load consistently.
In an effort to fix this I have loaded up the parts cannon and have since done/changed:

High pressure fuel pump for remanufactured unit with warranty
Leak off test which seemed ok (picture below) or within tolerance anyway (performed on hot engine until 1 tube became full)
Changed all low pressure fuel lines (fuel filter to LP pump, LP pump to HPFP, HPFP to the fuel rail at pressure regulator/valve end)

Unrelated: had black death on cylinder 5 so changed injector seals for the thicker honda ones and cleaned seats up real well etc with correct tools, slight cutting where needed

I can now see what seems to be air in the brand new fuel lines between filter and LP pump and LP pump to HPFP (HPFP to rail one seems ok no bubbles in that). Video's linked below
I installed these just fine and smeared a small amount of grease on the dry o rings to ensure no tearing and a good solid seal. 2 x hoses that have bubbles are genuine items from dealer. I am at a loss as to what is going on now and how this is happening. Any ideas would be massively appreciated!

air bubbles videos:
filter to LP pump:

LP pump to HPFP:

leak off test pic

 

[alexanderfoti]

Did you change the quantity control valve on the high pressure fuel pump?

Leak off test needs to be done at fault scenario (so empty all bottles, rev to 4k for 15 seconds, then compare volume).

Your fault code is also missing important freeze frame information. Is it under shooting rail pressure or over shooting rail pressure?

 

[smanderson117]

Did you change the quantity control valve on the high pressure fuel pump?

Leak off test needs to be done at fault scenario (so empty all bottles, rev to 4k for 15 seconds, then compare volume).

Your fault code is also missing important freeze frame information. Is it under shooting rail pressure or over shooting rail pressure?

Thanks for responding. Not sure what the quantity control valve is, the HPFP was changed for a new remanufactured unit and looks to be purely mechanical on mine, there's no electrical connectors to it whatsoever. I have changed the pressure regulator/valve at the back end of the fuel rail

That makes sense, will repeat leak off test with revs, much appreciated

I just have a cheap chinese reader that will not read rail pressure unfortunately, will try to get someone with a better unit to scan it if possible.

Thanks again!

 

[fabes]

Where abouts are you?
Someone maybe able to recommend local help....

 

[smanderson117]

I'm in Warrington. To be honest if I don't get it sorted soon (got a few last things to try) I am going to try Merx-Cheshire in..well...Cheshire It's 40 min drive but they come highly recommended. I just always seem to think the next thing I try will fix it, but so far, has not been the case haha!

 

[star]

Did you do a leak off test at higher revs, a combination of several high leak offs but not out spec would give you the same problem.

 

[smanderson117]

Did you do a leak off test at higher revs, a combination of several high leak offs but not out spec would give you the same problem.

I did not, now that yourself Alexander mention it, might be worth me doing the leak off test held at higher revs as you say. Will do this when I get chance, probably at weekend. Thank you