Hi,
I have a 92 D250 5.9/5 spd with 247K thats giving me problems. I bought it a couple of months ago and it developed a "miss" that has been getting worse. It runs smooth at idle to around 1400 rpms then it starts to run rough. It seems to smooth out a bit then starts in again around 2000 rpms. When I'm driving it, it pretty much does the same thing. I've replaced the filter, lift pump. I pressurized the tank, I've tightened all of the fuel line fittings and cannot find any leaks. I used some injector cleaner and It could be my hopeful imagination, but it seemed to run a little better. Does this seem like an injector problem? Or??? I appreciate any help. Thanks, Craig

 

At first I would have said fuel filter but then you changed it so thats good. Does it start like normal? If it does I would say that your fuel supply is fine.
Make sure that the wires on the fuel shutoff solenoid are tight/snug.

I think your on the right track with an injector going bad. Easiest thing to do would be to take them out and have a shop check them out. I took mine out a while ago and just had a shop clean them up and re-set them just so I would know that they are good, cost about $100 for all 6. If you need new tips they should cost you about $40 a piece.

 

You can find the bad injector (if that's the problem) by loosening the line while the engine is missing. The one that doesn't make the engine run worse when you loosen it is the bad one.

Another possible culprit is retarded timing.

 

Thanks for the help. I checked everything you guys said and it doesn't seem to be the problem. I talked to a mechanic at Southern Oregon Diesel and he said that's about all it can be besides the injector pump. So........Are there any recommended places to buy one? Thanks again, Craig