I recently bought a new to me 95 ctd with only 71k. It seems and sounds to me that one of the injectors is not firing. It will start and run and when you loosen the injector fittings on 1,2,3,4 and 6 the motor will change pitch and spit fuel from the fitting. When I loosen 5, the motor doesn't change pitch at all but it does spit fuel. The motor has very little power and barely made it up on my trailer. I can hear the turbo whine so I'm pretty sure it is working and there doesn't seem to be any strange valve sounds. Though the truck has very few miles I am sure it was worked hard because it came from the mining industry. Just looking for second opinions and anything I might be missing. Thanks, Don.

 

Very possible something beside injector. Put # 5 injector in any other hole and see if problem follows injector. Pull vcover and see if anything unsual with with valve train. Sometime as you crank engine you can tell if one cyl is weak. It sort of misses the compression stroke on one cyl.

 

I think you just answered your question. It sounds as if the injector is working fine, but there could be something else wrong with Cylinder #5. Compression perhaps?