Ill get right to the point...
*Check to see if fuel is getting to the engine
*Check to see if fuel is passing through the fuel filter and into the inejction pump
*Check to see if fuel is getting to the injectors (if no, check fuel shut off solinoid for power, if power is present, disconnect wire and touch to post with power..clicking noise whould be heard..if not, a new solinoid is needed..note that a sudden solinoid failure would lead to immediate shut down, not sputtering etc..)
*Check fuel return check valve for black or metal particles..valve should move free and return (If particles are present, governer weight retaining ring has deteriorated..Injection pump must be rebuilt and fitted with updated STEEL retaining ring)
If engine has fuel going to the injectors, but still wont start or run, resort to the gas rag trick...The engine will start, if the engine does not run on its own after doing this a few times, its probrably the injection pump.