Hello.
I have an Audi A6 2.5 V6 TDI AKE engine (210k km ~130k miles) which refuses to start.
The car had a faulty main injector that was replaced.
Thing is that when I tried to prime the injection pump, I can draw almost no fuel on the return side of the fuel filter.
Tried to prime it from feed side (from filter to injection pump) and i keep on getting a lot of pressure on the feed side, but very little amount of diesel coming out the return side.
Is there anything that might restrict the fuel flow inside the VP44 pump ? As far as i could tell, it's not a common fault (restricted fuel flow). 
Anyway, after insisting on the starter for about 15-20 sec i got this code (might be unrelated)
01441 - Fuel level sensor
- Faulty signal
- Permanent
Timing seems to be in sync. Only suspect thing is that i cannot prime the injection pump, other than that everything seems normal. 
ps. There is diesel squirting at union nuts. Engine was dead before main injector replacement. Fuel lines are ok not restricted.
Thanks, and my apologies if there was already a thread on this (i didn't find it).

came across this post is it any help if you read though a fault was found and fixed

http://www.vwaudiforum.co.uk/forum/showthread.php/92889-01441-low-fuel-level-sensor

Update: 

Checked the fuel level sensor; indeed i believe it's faulty. Each time i connect my multi meter to the pins I get a random reading for less then second (130,80,50,300,etc) then it goes to 1.

Also, i started the car on brake cleaner. After a few surges of rpm, it settled to idle rpm, but the acceleration is dead. Absolutely no response. The engine was stopped and restarted a few times, and there was no problem, up until about 10 min in it got below idle rpm and was struggling.

What are you thoughts ?

Is it just the lift pump, or the injection pump that is faulty ?  Or both ?

Thanks.

New Update :

Decided to let it run (idle was about 600 rpm). In about 5 min rpm got to normal values, and acceleration became available only once, after revving past 3000 rpm it dropped back to it's 600 rpm idle. After letting it a good 15 min at normal idle, car seems to be ok. Acceleration is always available, even withstood a 3000 rpm for about 2 min. Even redline. Everything seems normal. Did a code erase, and now i got no codes at all not even the fuel level sensor. 

I'm inclined to believe that the culprit is the lift pump not providing fuel to the injection pump. (to be determined, as i got no power on fuse 28, will check tomorrow)

Keep us posted on how you get on Andrei and glad your on your way to diagnosing the problem :) 

When you get a chance feel free to post a pic of your a6 in France in our Audi's from around the world section :)

Cheers

Steve