generator turns over if carb cleaner sprayed down carb throat, but only runs 3 seconds.

Odds are there are issues with your automatic choke, idler (governor) mechanism. For a shortcut this Saturday I placed a small piece of wood between the arm that controls the butterfly valve on the carb closing it all of the way and it ran like a champ. Without the wood forcing the valve closed the valve would bounce between closed and fully open in an uncontrolled ocilation causing the engine to eventually choke. I am looking for the proper and longer run solution to the problem and the web has not been much help. All of the sites say that this has to be fixed by a trained sears mechanic.