Dew-z - 11/4/2026 21:52

Solved: It was the injectors

So after my update above, I did the following:
-checked valve tapped clearance; good
-checked pump timing, pin method;good
-checked pump timing using timing light and neighbors snapon mt257 pulse adapter; good, showed pump/governor was advancing with increasing rpm
-had wife run combine while i rode on platform; everything fine, no collapsing hoses

The only thing I didn't check was fuel flow, I couldn't bring myself to hacking steel lines to do that.

Decided it had to be injectors, grabbed the old ones and got 3 up to spec and was happy with spray pattern. I had to get 3 new nozzles to get a good spray pattern on them.

Now the combine has more power, can go up to 6mph with 6 row chopping head in damp stalks today. Turbo boost is only showing 16-18psi, which I wish was a little higher but maybe the gauge reads on the low side. Neighbor was across the road, had him watch and he said absolutely no smoke.

The aftermarket injectors I bought were Reliance brand and were a direct cross from case number to cummins, J908511 to 3908511. Out of the box they were popping off between 3500psi and 4000psi. I didn't like that, so shimmed them to be 3450-3600. Maybe should have taken that as a sign and tossed them. Also, there are no markings on the nozzles, so you are just hoping the kid in the factory put the right nozzle on the right injector body. I'm really wondering if the spray angle was wrong on these but don't have any way to tell for sure.

Also, I'm kinda dumbfounded that I couldn't notice the low power in soybeans. Pushing a 30ft head, I would think it would be similar power requirements as 6 row in corn.

Well, after wasting almost 2 weeks of diagnosing, ordering/waiting for parts, and more diagnosing, its finally fixed. I'll sleep better tonight!

Thank you all for the help!