Ethanol based gas has probably been the greatest boon to small engine manufacturers there has ever been.
I had about 3/4 quart of gas left in my tiller from last year, and it was running, but very rough.
Dumped it out and let the gas sit, totally blew the tank dry and filled it with new gas, ran like a champ!
Gas that was dumped out soon settled and was literally about 1/7 water. (plus the rust the water caused).
Ethanol gas is crap, plain and simple.
Ethanol draws water to itself.