What year is your gen-set ? If its is your temp sender just unplug it (the temp sender that is) and see if it still acts up. It works on a grounding switch sender. It more than likely is a water pump problem if it runs for a while and then shuts down, if they don't move enough water the sensor will shut it down. Check the pump impeller and I'll bet you have a blade missing and is lodged in the line somewhere. Been there done that 2 summers ago. Chased it all summer cause I didnt get all the pieces of the impeller out of the lines after I installed a new one.