A fault (which has got progressively worse), is that occasionally when you rev to around 2000rpm (the rev counter doesnt work so that's a guess) it runs rough and white smoke comes out of the exhaust. The coolant is fine and hasn't ever needed topping up. The smoke is diesel-smelling, so that (in my mind) narrows it down to overfuelling at high revs, air leak, or bad injector timing.
This can happen at any time but mostly happens nearly all the time having just been started from cold. You rev it and it does the above. You let it idle then rev it again and it's fine.
I have (so far) fitted a non-return valve just before the pump, changed the fuel filter, and added a drop of injector cleaner directly into the fuel filter bowl. I have also added clear piping to the feed and return pipes and I am fairly sure it doesn't have any air leaks. It starts perfectly. It does seem better, and I have been for a 20 odd KM drive with no symptoms, but it will still do it when cold, and maybe more, but I don't want to keep driving it if it's overfuelling.
He has taken it to a garage who changed the gaskets on the injection pump (but weirdly didn't bother changing the fuel filter, which is why I have changed it). The garage basically washed their hands with it and said a new injection pump might solve the problem. The van was only a cheap van so it isn't worth throwing lots of money at it when it might be a simple fault!
At the moment I am about to swap the injectors out for another set of 1.9D injectors I have that are known good, but have seen that one has a wire which is for injector timing, the injectors I have don't have this so all I can really do is change 3 of them and see if that makes.a difference at the moment.
My thoughts on it are that either:
-An injector is sticking open or otherwise defective.
-The injection pump advance/retard mechanism in the pump is not working or the pump is otherwise defective.
I will change the three injectors I can and see if that helps but was wondering if anyone had had something similar before I condemn the injection pump and injectors and send them off for testing.
Picture below of the engine less upper inlet manifold/EGR.
Jack.