D2 5J - Spinning Right 'Round but No Go

Open the bleeder on the fuel filter tower and check how much delivery there is. If there isn't but a dribble, clean out the transfer pump relief valve. It could be stuck open preventing the pump from delivering properly to the injection pumps

With bleeder open on tower I get a steady stream of fuel out the tube but seems little difference between cracked & wide open. One of the reasons I changed the filters is I suspected them to be old & plugged which didn't turn out to be the case. Now the tower WAS still full (pulled the drain) prior to the change. But the pump being the lowest point I agree it could be the pump seeing a partial bypass if any sludge is there.

With bleeder open on tower I get a steady stream of fuel out the tube but seems little difference between cracked & wide open. One of the reasons I changed the filters is I suspected them to be old & plugged which didn't turn out to be the case. Now the tower WAS still full (pulled the drain) prior to the change. But the pump being the lowest point I agree it could be the pump seeing a partial bypass if any sludge is there.

I appear to get good flow out the bleeders. Get a drip curtain coming off the backside when they're wide open (at least on a couple). Would be great if CAT had done it where the bleeder orifices faced out instead of towards the engine. I know the lifter adjustment is out since #1 (only one measured so far) plunger appears to read more more than a crude 1.750...probably closer to 1.825 since the butt end of the caliper sits half way between the upper mounting face & inside of the lifter housing.
What I'm going to do is get the thing running again & have all 4 lines safely directed outward so fuel stream cam be observed & still get to the pinion lever.

When you set it to Run, does it sound like it's working against compression?

I appear to get good flow out the bleeders. Get a drip curtain coming off the backside when they're wide open (at least on a couple). Would be great if CAT had done it where the bleeder orifices faced out instead of towards the engine. I know the lifter adjustment is out since #1 (only one measured so far) plunger appears to read more more than a crude 1.750...probably closer to 1.825 since the butt end of the caliper sits half way between the upper mounting face & inside of the lifter housing.
What I'm going to do is get the thing running again & have all 4 lines safely directed outward so fuel stream cam be observed & still get to the pinion lever.

To be sure I'm on the same page. By "rocker covers" this means to remove the 4 covers on the side of the motor that decomp armatures go through?

When left cranking for extended time even in RUN then disengaging then re-engaging the pinion it will briefly sound like it's under compression...a brief moment of lugging before the pony evens back out. But no discernible difference between START & RUN.
((NOTE: Checked when lever is fully in the RUN detent there is still about 1/8in of slop in the rack pivots in the direction of the RUN pull & about 1/4in total of back & forth from the perspective of the arm ends.))

Previous few times it ran it took a long time with the lever in RUN before it would start coughing smoke & eventually catch enough to stay running. When it did it seemed to run fine. However this time I don't get ANY smoke out the stack.

When originally purchased the PO (an older guy) said "don't use this lever" when referring to the decompression & thought it odd when learned the proper start sequence. So first few times it was started the lever was left in RUN but even then it took most of a pony tank to start.

I'm fully expecting a problem on the fuel side since the lifter rack alone is already suspect. Before making any adjustments will pull the injectors so they can show me what they're being delivered. Good thing I nabbed that socket while it was still available.

Is the lifter rack free? meaning does it move freely when you move the throttle lever?

The rocker cover is topmost on the engine, held down by either 2 or 4 nuts (can't remember which) and lifts off to reveal the valve rockers. If there is no discernable difference between no compression and full compression, then I think you have a valve train issue. It should noticeably load on compression. The pony, if running correctly, will still run at the same rpm because it's governed, but it should sound like it's working much harder and the main engine should "feel" like it's pumping against compression. If you don't have any of that, then I suspect you're not actually getting compression. By removing the valve cover, you can check that the decompression mechanism is working correctly. It should not hold down the exhaust valves when set to Run - there should be clearance at all times. Maybe a couple of photos and a video will help us verify operation