Starting problems

[Max1939]

Hi all
I'm after some help please on starting problem with my 2006 320cdi.
It spins over but will not fire, eventually running battery down. If i recharge battery, it might start and be ok for the rest of the day but will be non start again in the morning. Had RAC out and he said lack of fuel pressure and is probably the high pressure fuel pump. He couldn't connect to cars ecu to see any parameters ie fuel rail pressure etc. The vehicle has done 188,000 miles and apart from starting problem and slight missfire at low revs it drives great. I tend to agree with RAC about fuel but the only problem I have is that there are no codes in the ecu for anything fuel related. Surely if it was the pump i would get low pressure codes?. I have ordered a new pump but I am loathed to fit it if this isnt the problem ( I can return pump if not used). The only other codes are to do with abs sensors and no. 5 glowplug open circuit, but it should still start on 5 cylinders. Has anyone else had a problem like this that could give me some advice as to what to do. Many thanks, Max

 

[Blobcat]

Hello and welcome

Have you checked the run back tubes for air bubbles?

 

[LostKiwi]

OM 642s are very sensitive to glow plugs and I'm informed use them while the engine is running on occasion.

 

[malcolm E53 AMG]

As above I’d check the low pressure fuel lines from the fuel filter for air leaks/bubbles this tends to manifest overnight and needs to purge through the LP/HP pumps first start of the day. I’d also replace the glow plugs they are obviously starting to fail and relatively cheap and easy to do. If you still have problems it’s a good idea to have the fuel rail pressure and injectors checked for spray pattern and leak off. This would be my route to finding a poor starting problem with such a high mileage engine

 

[mersum1es]

How in earth RAC diagnosed low rail pressure if they couldn't read ecu? Plus low pressure fault code is NOT recorded during the crank. HP pump failure is quite rare, unless you see a leak behind the pump (bolts will loose sometimes).

And you probably won't see bubbles in OM642, if there is a leak, it usually shows on moist hoses/connections because low pressure line is well overpressurized (unlike OM613 engines). Try switch key on ingintion twice before starting. If that helps, you have problem with primer pump.

Injector spill off measurement is good place to start, and also glow plug relay, it might be duff. Just be sure all plugs are ok before new control module, or it can be fried instantly again.

Get it plugged in SDS and you will know from live data is it rail pressure problem or something else (glow plugs, CPS /cam sensor...).