Its really not the ethanol, its the blend amount. Some gas distributors will put more in the gas because it's cheaper than gas.
That's what happen to me at RT,the blend was 19%. Man it messed up some stuff. I only buy Shell gas now.
I also bought one of these 12.00.You can buy them at most lawnmower shops. And buy a Mercury water separator. 80.00 gas tester