Engine Misfires: Smoke, Stuttering, Troubleshooting

Hello everyone,

Before I put my T3 van away for the winter last year, it sometimes 'only' had trouble starting when cold. The crankshaft damper was severely deteriorated, so I suspected a loose timing belt sprocket.

Da die Bus-saison wieder losgeht, wurde das alte Ritzel auf der Kurbelwelle entfernt, mit Handfräse geplant und ein neues Ritzel aufgebaut. Spanrolle und Zahnriemen wurden ebenso erneuert. Nach auflegen des neuen Zahnriemens wurde der Motor 2mal per Hand durchgedreht, danach nochmal alle Makierung geprüft. AEverything is fine.

If I start the engine now, it starts somewhat reluctantly, and it takes a moment for the idle to stabilize. If you increase the RPM, there are misfires, sputtering, and extreme smoke (it really stings the eyes ).

According to the TDI timing checker, it's perfectly aligned with the center mark. We tried replacing the NHG (presumably a component), but unfortunately, that didn't improve the situation.

I now suspect that the problem is likely only related to the pump.
What do you think?

Best regards, Gunnar.