A Diesel engine needs three things to run. Air, fuel, and compression. If you really have fuel to the injectors, then you need to look at air, and compression. At the end of the day, any kind of problem with the set, has to be fuel related, IF you have air and compression. It can be electrical related, but it all turns around fuel. Are you getting fuel under pressure to the IP? Are you getting fuel under pressure to the injectors? Are the injectors popping off? No fuel. No start.
If the air is good, its more or less a fuel problem. I would bet my last dollar that its not compression. This is one of the very best engines ever put into a gen set in the last 50 years. Are you getting idiot lights? If not, I would first check the air. Pull the filter, turn the set over. Do you feel the large movement of air into the air intake system? If so, that's probably not your problem.
I would then next crack the injector line the farthest from the IP, and crank it over. Bleeding the air out is not as easy as everyone thinks. When you crank it over, fuel shoot out of the lines.
Do not forget to make sure the batteries are fully charged.