Great to hear! How old are your batteries? I'd recommend having them load tested first. You'd be surprised how poor it will make these trucks run with weak batts. Then test your FICM. Those two areas (batts/FICM) are the resultant of probably 90% of cold start issues with 6.0's. :c:

One was replaced about 6 months ago and the other was about a year ago. Yes I know they should be changed as a pair, but I can't get my dad to listen to me...this is his truck. The older battery was load tested when the newer one was put in and it tested good. The FICM sits at 47.5-48 volts KOEO, Cranking, and KOER.

Yeah even when they test good, chances are that older one will die first and it will just bring the new one down with it.

Anyways, glad to hear it's going good now, and thanks for posting back to let us know too, so many people never tell us anything after.:c:

Another update. Dad started the truck up this morning i would say it was 40ish degrees out and he said it started right up no cycling of the key just wait for the GP light to go out and couple seconds it started. so i had to go out and check it. its been sitting for the last four hours and its 55 degrees out and it started up on the second crank. i would say that's good. I guess when i started the truck up yesterday there must have been air in the rails still.

It can take a while to get the air out, normally 40 miles of various driving should get it out.

Well i diffidently didn't drive 40 miles when i was running it Saturday. but it probably got 10 miles or more of hard driving between Saturday and Sunday.