7.3 do not like cold weather... Ive had 6 of them still have 3 .2 have had everything changed batteries ,solenoid ,glow plugs wireing harness and still have to be pluged in to start well. Weather is so fickle here on day its 30 at night next its -10 . So in the winter I just always plug it in it is so much better for the truck and easier on the motor. Maybe I get 500,000 miles out of them.:cool2::drink:
Started fine if all the glow plugs are working (including the relay), two good batteries and good starter.
One thing to keep in mind, the computer shuts off the fuel if voltage drops too low....the starter will spin til the battery is dead but no way will it fire....
If you aren't getting smoke out the tail pipe no fuel....
Mine would start with 2 working glow plugs below 0C/32F in several attempts
:cool2::drink: