We were finally able to get schedules to match and run some tests. Here is what we found:
1. Engine will only start with a little shot of starting fluid. Without it, it only cranks.
2. Engine will not stay running at normal idle RPM, but will stay running over 1000 RPM and the truck can be driven.
3. Injector buzz test passed with no problems.
4. When we tried to run the cylinder contribution test, the engine died as soon as the first injector was dropped out by the test - I don't think it related to that injector. I think it is because the RPM dropped too much. We repeated the test and the same thing happened again.
5. He has a DP tuner, and the engine will only stay running if the tuner is on the high idle program. If you take it back to stock, the engine dies immediately.
The IPR Duty Cycle is at about 14% with the engine off, jumps up to about 65% while cranking, and then comes back down to about 14% once the engine is running. If I remember correctly, ICP was around 650-700 psig. I don't have the list of the codes we pulled, but he wrote them down and should be able to provide them. I remember seeing the code for ICP hi/low - don't know if it's related to the DP tuner or not.
From what he told me, he has replaced the fuel filter, injector cups & o-rings, and the IPR.
It seems like there is not enough oil pressure to fire the injectors while cranking and at normal idle speeds. The starting fluid is giving the engine something to fire on, and then once the engine starts and comes up to higher idle, the oil pressure is high enough to fire the injectors.
Any ideas? Thanks.