This is what I would do. Fuel in tank of course.
First, put a battery charger on the batteries, they will need it.
Second, make sure the IP is clicking when the key is turned to the on position. Dont get it mixed up with the glow plug relay clicking on and off. Put your head by the IP and let someone turn it on. If you can hear an audible click, your go to go. Thats the FSV (fuel shut off valve). If it doesnt click, the IP wont push fuel.
Crack the injector lines. Crank for 15 seconds, and wait 2 minutes. If you dont have fuel at the injectors in say, about 4 goes of that, move one. Next, there is a shcraeder valve (sp??) at the filter head (like you would find on a tire). With someone cranking, depress and see if fuel comes out. If no fuel comes out, we keep moving back.
For good measure, you can go ahead and put a new filter on there, filled with diesel/fuel additive. Its good to change them anyways.
Next is the fuel pump, on the bottom passenger side of the block. Find the line going to the IP from the fuel pump. Take it off, and have someone crank for a second. If no fuel, take the line from the tank to the fuel pump off. If you have fuel, your fuel pump is bad. If you dont have fuel, keep moving backwards all the way to the tanks.
Thats what I would do.