VP44 fuel injector on Audi A6 AKN model drawing air, causing starting problems in the V6 engine (Solution)

"Help! My VP44 injection pump on my Audi A6 2.5 TDI is drawing air. If the car sits for more than 5 hours, it won't start. There's no air in the clear fuel supply line, but when I use a vacuum pump on the return line, a lot of air comes out. After pumping about 5 times, the engine starts immediately without any problems. I've already disabled the fuel preheating, installed a new return valve, connected a direct hose from a canister, and even replaced the pump's shaft seal. The problem definitely comes from the ESP (Electronic Stability Program), but where?" I'm slowly running out of ideas.

Hello,

Okay, I'm ready. Please provide the German text you want me to translate.

O-ring, see exploded view diagram.

Best regards,

Edit Admin: Please ALWAYS pay attention to the copyrights of uploaded material!

Looking at the VP44 from the drive wheel, there is a fixing screw on the right-hand side, with a small retaining bracket underneath it. The O-ring, which is often hardened, is located on the screw and is in position 392. The Bosch part number is 1 460 225 083.

See:
http://eu-auto-2000.de/downloads/Ersatzteile%20%208778.pdf{MARKER}

Thank you very much, I will take a look. I also thought it might be somewhere in the suction side of the ESP. On the other hand, if the internal pump pressure is too high, diesel would leak out. I'll replace it right away.

I just replaced the O-ring; it was really hard, like plastic. Tomorrow is the big day, but I have a good feeling about it.

It's been doing this for two days now. When starting, it cranks a few times and then starts up very quickly. Thanks again for the tip. The mechanics quoted a price of €485 for the diagnosis, stating that the fuel injector control valve and the fuel pump in the ESP system were broken.
A new one would cost approximately €2500 including installation.