VE Pump Bleeding: How to Remove Air

Hello everyone,

Audi 100 TDI, year 1990, Bosch rotary injection pump: I checked the injection timing (didn't adjust it because it was okay), and now the car won't start. It won't start even after repeated attempts of cranking for a long time. No fuel is reaching the injectors. How can I bleed the pump? The 'Etzold' manual only says: 'Fill the injection pump with diesel.' But where? I've already tried filling it through the fuel inlet and the shut-off valve, but it didn't work.

Sure, no problem. Here's the translation:

'Thank you in advance.'
Björn.

The Bosch ESP usually bleeds itself automatically. If you loosen the locking nuts on the ESDs while cranking the engine and disconnect the contact at the shut-off valve (to ensure it doesn't engage), fuel should start to come out after a few seconds. Then, tighten the screws again and reconnect the shut-off valve - you're done.

My brother's Audi 100 always worked perfectly back then.

I tried it exactly as you described (without the power cut device), but it still didn't work. I'm still not sure when the power cut device is active – that is, whether it's active when there *is* power or when there *is no* power.
Björn.

Hello boernhard,

For all the Bosch VEs that I'm familiar with, the kickstand is down when there's no power, and it's up when there is power (i.e., while you're riding).
Have you made sure that you haven't reversed the fuel supply and return lines on the ESP (if you disconnected the hoses)?
If you've replaced the diesel filter, it's recommended to fill the new filter with diesel before installation, otherwise you might have to crank the engine for a long time to get it started.
In the ESP fuel return system, fuel must be discharged regardless of the shut-off valve when the engine is idling.

Best regards, Rainer.

Hello,
Okay, all I can say is that you really have to pump the brakes for a very long time until the system self-bleeds (at least 1 minute). I've experienced this myself, and I could hardly believe it. It's certainly not good for the engine.

Best regards, Albrecht.

'I had the same problem when changing the diesel filter. It wouldn't start. Then I unplugged the coolant temperature sensor, which made the car pre-glow, and after a bit of cranking, it started! Maybe that will help!'

Hi!

It is important that the tank is full during the fuel filter change!!!! This reduces the hydraulic pressure difference between the ESP system and the diesel level ("water level") in the tank! When I replace this part, I let the car roll down a hill with the ignition on and the gear engaged, while simultaneously pressing the accelerator. -> Of course, this only works in the mountains.

Best regards, Christian.