I ran across several articles, reviews, etc. referring to a fairly common problem with the fuel pumps. They would stop working after 20 minutes or so, cool down a bit, work again for a few minutes, shut down again, and so on. Those are my symptoms exactly! I went ahead and ordered an Airex E11015 fuel pump ( about $60 from Northern auto parts). I also have a new fuel filter coming, as well as the adapter to replace the carb mounted fuel filter. We'll see if these parts will eliminate the problem.