Hydraulic head issues. The bolt on the center of the hydraulic head gives you visual access to the plunger which should reciprocate 3 times for every revolution on the engine. Remove this bolt (after cleaning the area well) and with electric priming pump disconnected, have an assistant work the starter. It should reciprocate AND turn as it also distributes fuel to each cylinder ( one turn per two revolutions of the engine).
If it doesn't turn, it could be the drive key. This is designed to shear to protect the quill drive gears. If the drive key has sheared, the timing will be off and the pump won't time correctly. If it doesn't reciprocate, naturally there will be no fuel delivered.
One other issue here is the plunger button could have fallen off. This again is a sign of a binding plunger since the plunger spring should keep the button between the tappet and plunger. I saw this problem this week, the lack of the button will prevent adequate fuel. The stroke at 55 MPH and 8 miles per gallon at 2400 RPM is 0.70 mm, missing the button reduces the stroke by about 4mm.
Fortunately, the hydraulic head is easy to pull, just take pictures of how the lines are routed, the numbers on the head can get confusing. Pull the stop solenoid cover, the two safety wired screws retaining the control lever and the governor rod. Pull the control lever and look for the timing arrow, slowly turn the engine over until the red gear tooth lines up, then pull the 4 nuts and retainers, the head comes right off.
The retainer and button pop off, then the gear cover snaps off. The plunger spring comes off like an engine valve retainer, compress spring and fish the two retainer halves out. Now the key can be seen and plunger removed for cleaning. I use a gun cleaning product call Pro Shot Copper Solvent IV as it dissolves diesel gunk fast. Flush out with carb cleaner, then lube with clean fuel or light oil. The plunger must slide smoothly without binding.
Also, the timing mechanism will cause the quill gear to shift, there is only ONE window for reassembly, turn the engine over SLOWLY using a pry bar on the jackshaft between the transmission and transfer case to line the window up, then set the red timing mark one tooth back from the index point. Gimpyrob has a great photo of this.
Most injector line nuts are corroded, clean well before reassembly. Preservative oil is a good idea here.
