Hello,
Well here is the story I just bought a 1996 chevy c3500 with the 6.5 TD. Truck has been sitting for 3 years ( I put a brand new transmission in it 3 years ago and the guy never drove it since)
The truck fired up but was hard starting and only started with the pedal pressed. It through 2 Codes P0251A and P1216D and the truck has maybe half power I can get up to 60 mph on flat ground and hammer down. The truck downshifts and doesnt feel like it has anymore power in a lower gear than in overdrive. The truck is not making power.

Here is what I have done so far......

1. drained fuel and added 20 Gallons of fresh fuel and 2 bottles of diesel 911 additive

2. Found lift pump not working so it was replaced and now I have good flow from fuel filter bleeder and the T water drain valve

3. added inline frame mounted CAT Filter assembly before the lift pump

4. The truck idles well after the hard start

5. The truck blows no smoke besides a few small white puffs during hard start

6. The turbo sounds like it spools up I am not really schooled in these 6.5 diesels ( seems alot quieter than my D max )

7. The truck back peddles when I hit a hill of any sort

8. pmd has been relocated well before I ever seen the truck and does not stall out randomly like most pmd problems

Like I said I am very new to the 6.5 diesel I have a OTC Genisys 3.0 scanner and any tools I may need to Diag this truck (I Hope)

I have been reading about injector timing and optical sensors alot but would like some opinion from some seasoned 6.5 guys

It doesnt seem like anyone local or in this area are familiar with the 6.5 enough to really help Is this motor a real mystery?

Thanks for any help that is out there!

 

Sounds like the injector pump need replaced, sorry for bad news but I had one that did the same thing and it was the pump.
Bigdogjolly

 

Thanks for the reply That is what I am leaning towards........................