Thanks for the suggestions . . . here is what I found when running a few tests . . .
First, the recurring problem has been leakage around the metal (brass) thrads of the fuel line barbs in the pump head. The head gets hot, expends a bit and the fuel leaks. Tighten the barb by one turn to seal the leak, or add teflon tape, and next thing you know the housing has split. The last two replaced pumps have microscopic (or not so microscopic) splits in the thread housing. Various thread sealers did not hold. Anyone ever tried making copper to PVC pipe connections using just plain old threaded fittings? That doesn't work reliably either.
In checking around I found that the cube type electronic (as opposed to electric) fuel pumps, like the FACET/Purolator pumps, have a record of quick failures. The British motorcycle guys seem to like them a lot but they also say the pumps in the UK are different somehow from those sold in the US, anyway most of the reports over here say they won't stand up to mower duty very long, a matter of hours in some instances. I might get lucky but with typically only a 30 day warranty that's not a very smart bet.
OK back to the Kohler pump, . . . somewhere in one of my searches I read the word "redesigned" so in hopes they had changed to a metal housng (a futile hope of course) I went back to my local parts house and looked at a fresh pump. The redesign is this, the old metal thread connectors have been replaced by all-plastic snap-in connectors which use an O-ring seal. No expansive pressure is put on the pump housing and the barbs are held in place by a built-in snap ring device. Very nifty. The pump swap took 15 minutes.