2000 6.5 Crank no start

Hello, new here.

I just recently replaced a IP on a 2000 6.5 3500 GMC. prior to this, truck had been sitting for 6 months due to white smoke and no start. After IP replacement, Truck fired right up and would start/drive all week. During this week I was attempting to perform the TDC offset learn & adjusting the pump position ALL WEEK. Trying to get it within spec per repair manual -.25 -.75. Well after the second week, I came to the shop and went to start it to pull it outside, crank - no start. I thought maybe I adjusted the pump too far to the point it went out of spec. Nope. Made sure I'm getting fuel at the IP and lines. Made sure in tank pump was working, made sure glow plugs were operating, made sure there was no air in the system etc... at a full stop with this project. I tried 3 different known good PMD's. I'm stuck because the truck ran perfectly fine and then all of the sudden nothing. I didn't change anything, nobody even touched the truck. So I'm not entirely sure what changed. The only thing that I noticed was, on my Tech2; the last time I tried to re learn the TDC offset. The engine load was reading 99% with key ON ENG OFF. This was something new. as it would read 15-18% at idle. So, I thought maybe the pedal position sensor or ASSY was the cause, unplugging it changed nothing. I have looked & looked on this forum through numerous threads and nothing seems to be the same issue I am having. I've tried to disconnect the ECT while cranking to "induce a longer glow plug cycle", tried adjusting the pump numerous times incase it was out of spec. Before the truck stopped turning over, the last TDC learn I attempted to perform; wouldn't work due to "Engine Speed too High" when rpm's were IDLE and I was not driving; I think it has something to do with the engine load stating 99% on my Tech2. Please, I'd like to get rid of this dang thing haha. Thank you in advance and I'm sorry this is so long.

p.s. truck is a manual, if that changes anything. Yes, I have brand new batteries that I leave on a trickle charger & i left the block heater plugged in for 8ish hours last night. Still no change, just light white smoke coming out when cranking. New fuel filter installed as well.

2000 6.5 3500

How did you verify the glow plugs are working? If for some reason they shorted out and aren't actually working, you will have a no start situation.

Casey

Remove the intake top piece, then dribble a little clean diesel fuel into a few of the intake runners... about a half to one teaspoon in each runner.

Allow the glow plugs to cycle, then crank it. It it hits, stumbles and wants to start... the mechanical side of the engine is likely fine. It's not running on its own because the fuel injection system isn't delivering fuel... (assuming the glow plugs are working). Jim