My 9600 has excessive black smoke coming from the exhaust.  The combine does not smoke when it is not under a load.  Before you tell me what you think the problem is, let me tell you what I have done to it.

During wheat harvest ('09), this problem developed.  It was late during harvest, and I did not have much left to cut.  I first checked the usual stuff:  I made sure there were clean air filters in it, and I also made sure there were no restrictions in the air tube.  I also changed the fuel filters and I even checked the screen in the bottom of the tank.  I had been suspicious of the injectors (never been changed), so I put a new set of injectors in the engine.  This helped a lot.  The power was better, the smoking was less, some of the injectors looked pretty bad--so no matter what, it was a good thing to do.

Ok, after the injector change, the smoke was reduced by ~a third, but it is still excessive.  The smoke is black/dark, but the engine is not using oil.  Wanting to eliminate the problem completely, and after talking to the JD tech, yesterday morning I put a new injection pump on it (cha-ching $$ --$1900 exchange)

The power is better on the combine, and there were plungers and little widgets worn out in the old pump (so says the Diesel Injection guy), but the combine is STILL smoking too much !  I can let the combine warm up and then start cutting milo...it will not smoke too bad for about the first 30-45 min, then it gets worse, and stays that way.

I am wild about maintenance.  I change filters, oil, and keep clean fuel.  I dont know what else it could be except maybe the turbo, and I do not feel that is the problem.  I may have forgotten a step or two that we took before the injectors, but I went through "the checklist".

I would really appreciate any help or ideas, cuz its drivin' me nuts.  It did not used to be like this...The power is good, and the pump did make a noticable difference, but it did not (also) cure the smoking.  I know that there are no restrictions, and the engine is getting clean air.  I have checked for vacuum leaks, too.

TIA for the help... I am going to the field right now, but I will check back, here, sometime late tonite. Plz help.