Slow Cranking (Help??)

[Berge9798]

I have a 2002 powerstroke that I am having problems with the truck as 140000 on it and till about a month ago has had no problems. I live in Montana and the temp. has dropped and sense then my truck has been the biggest pain in my a**. If i don't plug it in and i come out in the morning it will not start. The temp here is not to cold i have a 99 that has 150000 on it and it starts like a dream and I don't even plug it in. So far have changed the starter on and that made a world of difference till last week when i made the mistake of not plugging it in and I ran the battery's down to nothing trying to get it going. After that day The truck turns over so slow. It seems like my Batteries have taken a crap but they test out fine. I even went ahead and changed them and no difference. It does not matter if the truck is cold or warm it still cranks super slow and almost does not want start up. Any Help would be great I am out of ideas what is could be short of going to get a new starter again.

[dieselburner21]

Im going to state the obvious, maybe its your GPR, you didnt say if you cjecked it or not. However I have good GPR, good glowplugs, and mine still doesnt like to crank if it dips below 20 at night. I know mine is because I didnt swap to 5w-40 on the last change. I would look into it if I were you 7.3L's are the worst in the cold and having a thinner oil in the winter would help your situation since your out of ideas

[Berge9798]

I have pulled my Valve covers and checked all my glow plugs all are in working condition. i checked the harness also and the relay is good to.

[19558077]

you need to use the advice of the posted link to properly check the gpr, and glow plugs, it sounds like your problem. good luck
Troubleshooting GPR & GP's

[dieselburner21]

What oil do you run and what grade?

[Berge9798]

I run 15-40 in it. and the cranking problem I'm having should not have to do with glow plugs i dont think. that would be the starting problem but when i crank it over it turns over so slow like if u had dead battery's