QSB 4.5 NOT START

[chrismds]

Found many times working on grape harvesters that when these 4.5's are placed under any load on start-up e.g. hydraulic pumps not displacing, the engine will over fuel and blow excessive white smoke on cranking but not start! Sounds rough but spray SOME solvent into air intake on crank and will start ok........afterwards starts and stops ok! I've changed speed/position sensors, fuel pumps, ecm's, starter motors, injectors, lift pumps etc. but nothing works! Not sure why they respond so poorly to load on startup.