1986 f250 with 250k miles. I have put new return lines, caps, injectors, injection pump, lift pump and it wont start. It cranks and blows white smoke out the exhaust meaning fuel is getting to cylinders. There are no leaks on the caps or lines l. I have retarded and advanced the IP to no avail. There is plenty of fuel pressure at the shrader valve at the fuel filter housing. The injectors are brand new. The IP was rebuild from a questionable rebuilder pensecola. I have tested with another IP from a different 6.9 I own and it still didn't start. Before any of this work the truck started fine in sub zero temps NOT PLUGGED IN. I live in Colorado and spend a lot of time in the mountains below 10 degrees over night. Started fine all the time. Now it wont start at all. My question is, will a rebuilt IP cause a scenario where the truck would now need to be plugged in to start? Would a different IP make a truck harder to cold start? If so, why?