have a nearly new kohler generator that starts fine ,runs for about 5 minutes and just shuts off. changed spark plugs, oil is fine just a little over full. is there a auto shutoff on them for some condition?

Water pump impeller is probley bad. Will shut off if it gets too hot. Watch and see if it's putting out water.

there are several different sensors that will shut it down, oil level, cylinder head temp, and exaust temp. check the water pump first.

I agree with the two responces above. After 5 minutes it gets too warm without proper cooling. Most likely cause is bad impeller in water pump or hull intake is plugged.

There's an auto shut off on all generatrs. Kohler generators shut down due to high coolant temp, low oil pressure, overspeed, maybe high exhaust temp. Check the gauges when it shuts down.
Gary

I agree,,,,,,, start it up and look for water coming out of its exhaust to confirm or elimintae the impeller.

Easiest way to diag

I had the same problem with my 7.3 Kohler. I found my oil filter wasn't tight and leaked which caused the oil level to drop below a certain level .Kohler has an automatic safety shut off for low oil level. I'll bet that's your problem.......