Van engine T4 ACV starts poorly in both warm and cold conditions.

Hello, maybe someone of you has an idea. My bus only starts with a cold start spray anymore.

Before, he was always there immediately. No memory errors!

It stutters around 2000 RPM and diesels at 120 km/h. Recently, it has also been cutting out occasionally while idling ? My first attempt was with a "Knackfrosch" fuel filter. No improvement. Then, the start of the funding has been checked, and it is okay.

Then I replaced all the light bulbs, two of them were already broken. Also, no improvement, and I had all the nozzles checked, which were also okay for their age. Now, the Bosch service believes that the problem lies with the pump, which is no longer able to build up enough pressure?
What do you think? Have you ever experienced something like this before?

Do you have a transparent fuel line in front of the pump, so that you can check if there is air in the system?

If that's the case, I would remove the timing belt. If that's also okay, and considering the previously checked items, would I also conclude that the issue lies with the pump?

I am assuming that you have already checked the obvious things, such as the start and amount of spraying, with VCDS, and therefore can largely rule out any wobbling or similar issues. Okay.

Greetings
Guste

Ok, thank you for the response. Next week I'll be building it, and then the Bosch service should come and check it

Hello!
So, ich würde mich erstmal trotzdem noch auf die Kraftstoffversorgung konzentrieren.

I also have an ACV, but in a construction truck.
also irgendwie um die 300.000 km,
with the pump, there was nothing. It's also still working perfectly.

What I noticed was that the tank had become compacted.
The fuel tank cap seals completely, and there is also a valve in the fuel tank ventilation.
that was settled.

But I only realized this by chance, without any problems, and I replaced the valve.

Then, as already written, while the engine is running, check the transparent fuel lines to see if there are any air bubbles. In normal circumstances, there should be a small bubble that moves back and forth. There should not be any continuous "bubble effect" detectable.

Furthermore, I've also experienced a number of other issues, such as damaged fuel pumps in the tank, and new fuel filters with tiny holes in the housing (original VW).
all possible leaky hose connections,
and leaky rubber rings on the frog
Huge amounts of dirt, rusted pipes, etc.
There have also been cases of damaged condensate drains in fuel filters.

Then, take a closer look to make sure everything on the fuel pump is sealed properly.

Furthermore, I would then try to run the engine from a verschandeln container with verschandeln diesel.
Before starting, make sure to bleed the pump. And then, let's see what happens. Will the CDU also be returning to the center?

I am not a psychic, but based on my long experience, I would say that it is often very small causes that are responsible, and you just need to find them. It's often quite complicated...

Another thing I've gotten into the habit of doing is checking to see what repairs have been done on the vehicle recently.
Sometimes, something gets stuck, squeezed, or damaged.

Hi,

I would first check the injection start with VCDS. And the two timing belts to the pump.

Hi, Rainer

Hi everyone, problem solved. The pump was faulty, so they removed the springs from the high-pressure part.
I had them repaired and reinstalled, and it's running properly again. It's amazing that he was even able to run.

Thank you again for your responses until next time.

Tyler5 wrote:

Hi everyone, problem solved. The pump was faulty, so they removed the springs from the high-pressure part. I had them repaired and reinstalled, and it's running properly again. It's amazing that he was even able to run. Thank you again for your responses until next time

Thank you for your feedback!