Did the fuel come from a bulk tank on your place?
Todays gas (ethanol or non ethanol) does not have a very long shelf life. Both start going bad 30 to 45 days after you fill you gas tanks. You have to use a fuel stabilizer like Startron, or Stabil, or K-100 to keep your fuel from going bad. In my area someone using a bulk tank have the most problems like the lack of power to not running. I have had several people have had carb problems on non ethanol gas. The local station doesn't sell enough.....gas is going bad.
I turn the fuel off at the fuel tank and let the carb run dry when I'm done using the tractor-engine for the day. Another thing I do is shake fuel container before I start the tractor-engine. The different additives in your fuel will separate with the heaviest additives going to the bottom of the fuel tank. Two cycle fuel is a good example. Try pouring some 2 cycle gas in a clear container without shaking the container.......You will get straight gas for a few seconds before you get the gas-oil mixture. The ethanol part in the gas is the heaviest additive. I try to leave the fuel tanks in my small engines empty and shake the fuel container before I add fuel to my tractors. I will shake/rock the tractor back and forth for 5 to 10 seconds to mix the fuel in the fuel tank. I've been doing this for 10-15 years with no fuel related problems.
Todays fuel is design for vehicles that have fuel injection and a seal fuel system. I read an article that had the suggestion of putting a plastic bag between the fuel opening and gas cap. This suppose to help keep the vapors from escaping from your fuel mixture. Not sure how much this will help.....planning to give it a try.
I been running E10 in my small engines 15 years with no problems. I will buy gas at the beginning of the month and add a fuel stabilizer. My fuel is stored on 2 X 4s so it helps from attracting moisture. I will shake my fuel container before I add any fuel to my small engine. Any fuel left will be added to my truck at the end of the month.
I have been running E85 in 2012 Chevy 2500HD truck with no problems. The gas mileage isn't same....$.40 to $.50 a gallon cheaper makes it cheaper for me to use.