AC 653 won't start

[ac 653]

I was using my AC 653 dozer, when it quit. I thought it may if run our of fuel, so i filled he tank and bled the lines. Cranked and cranked and nothing. Broke out the old starting fluid, and still no go. Let it sit awhile and gave it another go, with the same results. Need some insight on where to look, or in what direction to go. Thanks

 

[JDemaris]

Make sure the injection pump is actually turning when the engine is cranking. It has a shear-shaft built into it that is supposed to break in half if the pump turns too hard.