We have had the same sort of problems in the past with some of our smaller engines at the fire department, like on brush truck skid units, sump pumps, etc. The ethanol in the gas really will make your smaller hoses brittle and fuck up your carb. We would take the carbs apart ourselves to clean them, so it's not like anybody was really jerking us around. Finally we decided to wise up and turn the fuel flow off while the motor was running and let it burn off what was in the fuel line and let it shut itself down. That seemed to help us out quite a bit. Now since a station in town has started selling 100% gas and we use that, no problems whatsoever.