Ethanol = Water, Gasoline = Fire
Ethanol is
, and small engines just don't run as well with it. My best advice is to find a gas station near you that sells 100% gasoline, no ethanol. Your engines will run best on that. You can find stations near you at
Pure-gas.org. Yes you pay more for it, but if you don't have to drop your carbs every year it's more than worth the headache in time and swearing.
Alternatively, when I couldn't get 100% gasoline I used
Sta-Bil Ethanol Treatment. This one is the marine variant, although it works just as well in small equipment engines too. I've run it through several lawnmowers, weedeaters, and a chainsaw before I found a 100% gas station.
ISO-HEET is also a good product if you've left ethanol gas sit a while before adding a stabilizer.
<Steps onto soapbox>
Ethanol is just a bad idea all around!
This is horrible if you are letting the mixture sit for any period of time more than a couple weeks, like unused lawnmowers, go karts, chainsaws, weedeaters, etc over the winter months. Here's why:
A) It increases the octane rating of a gasoline/ethanol blend.
Wait that's good right? No, because the oil companies are using the increase from ethanol to get to the minimum octane rating and hence are using a lower octane rated gasoline in the mixture.
B) Ethanol does not chemically bond with gasoline.
This means that it's simply a mixture of gasoline and ethanol, and will separate out from each other given a time frame. If you don't know what a separated mixture is, take a small clear glass, pour water and some vegetable oil in it. The oil will always rise to the top when it sits, no matter how much you stir it. Gasoline and ethanol will do the same thing, although not as quickly. You can also search Youtube.
C) Ethanol chemically bonds with water. (Drying agent)
Ethanol will remove water from anything around it. Because the ethanol-water molecule is heavier than fuel it sinks to the bottom of the tank separating into layers even faster. Of course the bottom of the tank is right where your fuel pick up is. So when you go to start your engine after it's been sitting, you're getting mostly the ethanol-water mix and not the gasoline you need. Now remember the gas that's left is a lower octane than it was with the ethanol mixed in suspension. Stirring up the tank, may help, but you're still trying to burn ethanol-water molecules. Remember you're also dealing with the separated fuel that's in the fuel lines and carburetor.
D) Ethanol requires a higher temperature to burn.
Yeap, you've got a cold engine that's been sitting for months, trying to get it started by burning a gas-ethanol mixture which requires a higher temperature and hotter spark to burn. If you changed your spark plug, or cleaned it off, and have a good strong ignition coil this may be fine. Until you realize you're now trying to burn the ethanol-water molecules first from the bottom of the tank. Now your increased spark requirement must also break the ethanol away from the water first, making it a higher requirement than most small engines can manage.
E) Ethanol is a solvent.
That keeps my engine clean right? Well yes, but what happens you use a solvent on gaskets, seals, and hoses which are made of soft pliable rubber? You guessed it, it slowly erodes the rubber. Combine that with the drying agent factor (which can pull moisture out of the rubber) and you get dried up rubber which leaks, breaks easily, and eventually just falls apart. Well it doesn't just disappear, that dried up rubber has to go somewhere. Most if it goes into the fuel system where the ethanol has been working on it from. So now you've got little bits of rubber gumming up and clogging parts of your fuel system that should flow freely, and other rubber parts that start leaking into areas they shouldn't leak. This is how ethanol destroys carburetors. It works slower on hard plastic and fiberglass, but will erode them as well, adding more debris to the fuel line. The older the rubber/plastic/fiberglass is, the easier it is to erode because it has already lost moisture to the surrounding air.
There are other environmental and economic concerns if you really want to go that far into it, but the above is the actual end user type of stuff. Honestly I make extra effort to buy non-ethanol fuels. I drive an extra mile each way to a gas station that doesn't sell any ethanol, and pay more for it as well. How much more depends on the market, but the average cost is an extra 5-15% over the ethanol fuel based on where you live. Sure you are only getting 10% more gas, but you're also saving on maintenance.
It should be noted that even cars and trucks, unless they were produced in the last several years, will eventually suffer the effects of ethanol. I have a friend who runs an auto repair shop out of his home garage, and he is constantly replacing sections of rubber fuel line on vehicles. Newer vehicles have all aluminum or steel fuel lines so this isn't a problem, but it will still erode the rubber O-rings that are used between fittings.
Seafoam.
