No start
 

Ok, so my 2002 lb7 is not wanting to start in the cold. People said to rebuild the fuel filter housing because thats a common problem thus causing air in the lines. I tried that and had no luck. Then i thought maybe the whole housing was junk not just seals so i then completely replaced the hole housing. I later came accross the same issue. After that trial and error i changed my glow plugs (a few were shot and the others weren't too far behind). It was cold out and i was having good luck with that until it started to get really cold 25 or below. It gets plugged in every night as well and now it turns over but will not fire to save its life. Ive tried priming it cause that has worked before but still nothing. And it does have 2 new fresh batteries put in november of last year. The injectors were also replaced by local dealer around 35k miles ago. No check engine light or any sort of codes popping up because i thought it could be my glow plug relay but no codes. I am stumped and have tried every little logical thing i can think of. Anyone else have this problem that found the solution?

Any help would be greatly appreciated

found this post from the other day.
https://www.dieselbombers.com/chevy-...ontroller.html
Does it have a fuel heater?
sorry not up on the Duramax's