I just replaced oil cooler gaskets and put everything back. It required only about 5 starting attempts to get car running. I turned it off after about 5 sec and went to collect some tools. Then, new starting and car stayed running about 10 sec and the died. Would not start anymore (cranks though).

I decided to bleed the fuel line, noticing pump works only about half a second once ignition turned on. It has used to pump at least ten seconds once ignition is switched on.

Tank is nearly full. The pump itself works I guess as it spits diesel for that half sec. (checked from hose disconnected from fuel filter) Also relay, fuse etc. must be fine. Car has fairly new rear SAM. What all is involved in pump control? I think that half sec spit is not enough to fill high pressure pump. The strange thing is that car started twice. No fault codes (checked with iCarsof MB2.0). I don't really have any ideas what to check/do. Any help would be highly appreciated!

 

Check with multimeter whether you get voltage to the pump for half sec only.

 

I bypassed pump relay and pump works. All fuses are fine in front and rear.

I think the issue is wider than I though. When pump is forced to run, car refuses to start. Apparently ECU prevents it also by some other means but just not turning on the pump.

If I disconnect (loosen) the pipe going out from high pressure pump, there is not any high pressure spray you'd expect to see. There are two electrical plugs on high pressure pump, so ECU controls that somehow as well? These two plugs stayed connected during the seal operation.

What data ECU gets or doesn't? Again, car was running for a short period before it died. I am really out of ideas

 

Fixed!
It was just fuel common rail pressure sensor plug that was not plugged in properly. I remember, I needed to unplug it at some point to reroute the wire. Probably I just plugged it loosely to see how the wire goes and then forgot the whole plug. It happens. shame on me though.

Thanks anyway for listening.