The biggest thing with ethanol fuel is that it loves absorbing moisture, which we all know. My Honda 40hp had three carbs on it. If that motor sat for anymore then 2 weeks it was a complete dink to start. The fuel in the carbs (less then an ounce per-carb) are open to the atmosphere (all carbs need atmospheric pressure to function) and the ethanol fuel would go stale that fast. If I drained the carbs after using the motor for a day of fishing. The next time I would go out, I'd use the primer bulb to refill the carbs and that motor would start right up. I did also use Seafoam in every tank of fuel. The fuel in my sealed tank would stay good because I made sure that the fuel tank cap was actually working and sealing the tank when there was no draw from the motor. In other words a bit of prevention and a regiment of maintenance is all you need to deal with ethanol fuel. A lot of onboard fuel tanks have a fuel tank vent that is open; we've all seen it at the gas stations, where gas would spill out the vent when the fuel tank was full. That fuel in the tank is exposed to the atmosphere, depending on how humid it is that fuel can go stale if not used right away. We don't see this problem of stale fuel in the automotive industry. Emissions standards (no hydrocarbons are allowed into the atmosphere) require the fuel delivery systems to be completely sealed. It is called the evaporative emission control system (EVAP). This system works only with fuel injected motors. They don't need air pressure to atomize the fuel and can have sealed systems. At the end of this long post all I can advise is keep the fuel, you're using away from the air as much as possible...
Just a side note and a bit of humor. My neighbor next door to me at the trailer park, buys a 2 gallon can of gas every spring. It's nicely sealed not to spill in his car. He opens the can, puts the pour spot on and fills his lawnmower; but leaves the gas can open for the rest of the season. A few weeks later he doesn't understand why the mower is hard to start and if it did start, it ran like a bag of crap. I'd go over drain the fuel tank and carb and then put gas in from my sealed can. Two or three pulls and it starts and runs like new. He doesn't understand why his fuel is bad. "I'll never buy gas from that place again" NO buddy seal you gas can!!!
Dan...