Crank no Start Diesel FORD\International 6.0D

Hello everyone, I need help with an International 4300 6.0L Diesel (or its sister engine, the Ford 6.0L Diesel). The issue is a crank but no start condition.Background:The truck was brought in with an intermittent no-start issue. The customer had previously tried to start it to the point where they burned out the starter.Initial Diagnostics:After running some basic diagnostics, we found that the ICP (Injection Control Pressure) percentage was too high during cranking, between 70-85%. At the same time, the high-pressure oil system was only reaching about 300 psi.
To address this, we replaced:

• All injectors o-rings (with OEM parts),
• "Dummy" tubes,
• All related gaskets,
• The ICP valve.

Now, during cranking, oil pressure in the high-pressure system reaches up to 1500 psi, which is much better, but the truck still won't start.Current Symptoms:

1. After cranking for about 10-15 seconds, white smoke comes out of the exhaust, and it smells like unburnt fuel.
2. If we spray a small amount of starting fluid (the "magic spray"), the truck starts and runs fine. However, after the engine is off for a while, it goes back to the no-start condition.

Any ideas?

It's been a bit since I worked on a 6.0L, but I remember having struggles with no starts and long crank times after high pressure oil system repairs. Ford had a TSB out on it for some model years:

 

The TSB talks about doing several high load runs, but I also found some extended idling time really helped. 45 minutes or more if possible.