I have read many posts and watched many videos to try to fix my no start issue. The story to date:

Truck ran but was leaking oil (HPOP gasket) and just started to have some tough starts where a cloud of white smoke would be generated while cranking and eventually it would kick in. This happened about 50% of the time and that mixed with the oil leak it was time to put the work truck into maintenance (I work for myself, so I am also the maintenance department).

Changed the HPOP gasket and went to start it. Now it cranks, no smoke, no start.

After testing, I started changing parts. I've changed the IPR, the CPS the oil pressure switch the glow plug relay (this tested bad - no connectivity).

I should note that my friend who was helping me put the wires on backwards on the glow plug relay and after fixing to proper position (dual wires towards cab), the GPR still did not show any voltage with key on, so I bought a new one. The new one has a hum to it, the old one clicked, the new one shows voltage. I forget what it was, but it was lower than the volts from the batteries. I compared this to my neighbor's trucks voltage and basically got the same % difference (a few volts lower). His truck runs I should note!

I swapped out my IDM with my neighbors. Tried his in my truck. No start, no smoke. I tried mine in his truck, started right up.

I checked the diode, swapped it out with a spare, checked all the fuses in the truck with an ohm tester.

I cleaned out the little fuel screen and changed the fuel filter.

I have fuel in the bowl. I have batteries hooked up to a charger so that voltage is 12.6v.

The crank position sensor (I think that it what is called) - it is down below towards the bottom of the belt - swapped it out with a spare. Still no start.

While I know that it has nothing to do with the no start, well at least I think - I looked at my back pressure sensor and tube which were completely clogged. Cleaned out sensor, am waiting for new tube to arrive (figured it was only $12, so why not start new since there are so many new sensors on this! I also bought a new sensor.

I'm at my wits end (and also near the end of my credit limit for parts ....

I am now waiting for a friend to arrive with his android phone so I can plug in the OBD2 bluetooth reader to use Torque to read cranking pressures (fuel and oil) to see if these fall within acceptable ranges.

We did test to see if oil would shoot out while cranking. I was on the key side, my neighbor was on the engine side. Given he has owned this truck (I bought mine from him) for 20 years I know his confirmation that there was oil pressure.

I'm at a point that the original project of swapping out the gasket on the HPOP is going to be undone and redone to check to see if my friend messed up any of the connections. I did check to make sure that the hoses from the fuel filter were going to the same spots as my neighbor's truck - which they do.

Any help/guidance would be most helpful. I was happy to eliminate the IDM as being the problem as that would have set me back more $ and produced the same results to date - nothing.

I know most of the no start posts I've scoured through are older so I really hope that all you helpful people are still using this board!!!!

HELP!