Cummins/Onan shuts down when majority of load is dropped

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My Cummins/Onan QD-3200 RV diesel generator with 220 hours on it just started to do this. It will be loaded to over 50% for hours with no issue then when most of the load is removed it will run for another minute or so, then drop RPM and just putter out. Oil, fuel filter, air filter all new 20 hours ago, oil level is good. RV fuel level over half. Outside temps very high, triple digits. Not sure why it's started doing this.Miller Challenger 172Miller Thunderbolt AC/DC 225/150Miller Maxstar 150 STLVictor 100CVictor JourneymanOxweld OAHarris O/ASmith O/A little torchNo, that's not my car.
Reply:Is it a mechanical injection engine? It sounds like a governor issue not load compensating fast enough, but I may be wrong since I'm not really familiar with it.NRA LIFE MEMBERUNITWELD 175 AMP 3 IN1 DCMIDSTATES 300 AMP AC MACHINELET'S GO BRANDON!"Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety.” BENJAMIN FRANKLIN
Reply:Many types of engines hate to go from a high load to little or no load,, especially when the ambient temp is high.Could the load and high air temp have the engine operating at an overtemperature situation??I have a 50 HP diesel tractor, if you flail mow in tall grass at too much ground speed, on a hot day,,  the engine will stumble, and stall.(tightening the fanbelt helped my engine problem,, but, it is not perfect)My temp gauge showed slightly high temp, but, the engine coolant was not boiling over,,
Reply:

Originally Posted by bigb

My Cummins/Onan QD-3200 RV diesel generator with 220 hours on it just started to do this. It will be loaded to over 50% for hours with no issue then when most of the load is removed it will run for another minute or so, then drop RPM and just putter out. Oil, fuel filter, air filter all new 20 hours ago, oil level is good. RV fuel level over half. Outside temps very high, triple digits. Not sure why it's started doing this.
Reply:

Originally Posted by tadawson

I'll guess gunk in the idle/low power circuit causing the mixture to lean out and die when off throttle . . .
Reply:

Originally Posted by bigb

My Cummins/Onan QD-3200 RV diesel generator with 220 hours on it just started to do this. It will be loaded to over 50% for hours with no issue then when most of the load is removed it will run for another minute or so, then drop RPM and just putter out. Oil, fuel filter, air filter all new 20 hours ago, oil level is good. RV fuel level over half. Outside temps very high, triple digits. Not sure why it's started doing this.