BMW 325TDS: Intermittent Starting Problems

Hello, I'm having another problem again:

BMW 325TDS, 143 hp, new filter, new glow plugs, some oil residue, oil leak lines checked, 2 leaks replaced (slight leakage on the front of the 2nd ESP), VP37 injection pump.

- Occasionally, the organ doesn't start up within 20 seconds.
- rarely starts immediately.
- Starts much faster when cold compared to when warm.
- No improvement was observed even when increasing the engine speed using a dynamometer.

Yesterday, after turning it off, I noticed that air bubbles were rising from the ESP towards the supply line.


The original fuel filter holder (which was replaced due to a leak) has been replaced with an aftermarket holder (which the original filter fits). Is there a check valve in there that is now malfunctioning?

If the fuel injection system were dirty, wouldn't that also manifest as a jerky feeling? Also, the idle is always constant and perfect; there's no sputtering or anything like that.
Cleaning the MSW would not be too (especially cost-)intensive, and it would also be enjoyable if it is likely to be the cause.


Yesterday, while driving on the highway, I was going a bit faster for a while. Afterwards, the car took an extremely long time to start.
Later, at 180 km/h, the power suddenly dropped; eventually, it could only reach 120 km/h. (The filter was changed 50 km ago.) After a while, at 120 km/h, the power improved again.
Problem wird grösser, wenn ich ne zeit lang schneller unterwegs bin. Tank ventilation?


Thank you for your advice!

This morning, I only loosely placed the gas cap.
And lo, so far, it has started up almost immediately about 10 times.
I hope that remains the case, even when the tank is vented through the lid.

That leaves us with the rough, relatively loud engine running at below 1500 RPM.
Could it be that the ESP chain length was never correctly adjusted, and that's why it's causing this issue? This would shift the injection timing later. Could that cause a rough-running engine?

Quote:

Was if the ESP was never correctly adjusted due to the chain length? This would cause the injection timing to shift later. Could this cause a rough engine running?

It uses a conventional injection system with a needle lift control, after which the injection start is regulated according to a pre-defined map. If the actual value deviates significantly from the target value, the system enters emergency mode.

Sold and the T4 has been taken out of hibernation!

Thank you to everyone who viewed the thread, and to everyone who wrote about this topic in the forum.
I managed to refresh my knowledge on quite a few things while browsing the forum.