Hi all. I am new to this group. Thanks in advance for any help. The truck is an 2001 Ram 3500 6 speed manual 5.9L 24 valve cummins, totally stock except for a Fass lift pump. The power is down about 60% sometimes. It feels like a half dead pedal.The power is fine or down 60%, never in between. The problem started occurring once a week, then 3 times a week, then twice a day, then most of the time. Now it is down on power almost all the time. This was over about a six month period. No difference hot or cold. No codes stored, using the key on three times technique to check. Never less than 14PSI at the injection pump inlet. First I replaced the TPS (apps) and fuel filter. No difference. Then I replaced the injection pump (vp44). No difference. Then I was really scratching my head. I have a known running parts truck so I swapped out more parts. Those include Map sensor, cam sensor, engine ECM. Still no difference at all. The problem did not change AT ALL with any of the above parts. What am I not seeing? Any help would be greatly appreciated.

 

The turbo charger is what gives these engines their power. I don't know much about these fixed geometry turbos , but it sure sounds like its not building enough boost sometimes. Do you have a spare "working" turbo to swap?