Agreed with the two above suggestions. First ensure that the pump is properly primed -- much faster and easier on your starter if you use some kind of external feed pressure (e.g. hand primer bulb or low-pressure electric lift pump inline before fuel filter) to help the process along, and even then it does take considerable cranking. Give your primer bulb some good squeezes until you feel some resistance build up, or energize your lift pump, then keep injector unions loose and hold fuel pedal to the floor and crank until a good amount of fuel is running out of all six of the unions.
Then you get to close them back up, and see if it will start. If it does, hooray. If not, you get to figure out whether it is a fuel delivery or injection timing issue, or even a glow plug problem. Look and smell for white smoke from the exhaust. If present, then you are getting fuel into the combustion chamber, but either at the wrong time or without preheating from the glow plugs. If it will start but only poorly, or won't stay running, or makes big smoke and noise after it starts, then you need to check timing again as well. If no run and no smoke at all, then you are still not getting fuel through the injectors, which, assuming the pump is adequately primed, indicates an internal pump problem such as a broken high pressure piston or a problem with the throttle linkage that you didn't catch before. Hopefully you won't have to go there!
My guess is that once you get it primed and timed, it will fire up just fine.
