How to Fight Ethanol Problems in Small Engines

In 2005, Congress instituted a new renewable-fuel standard. In response, refiners removed methyl tertiary butyl ether (MTBE) from gas and started blending fuel with ethanol. Ethanol helps reduce petroleum use and greenhouse-gas emissions. Derived from corn, it supports U.S. agriculture and promotes energy independence. Ethanol, however, can be bad for small engines.

These problems center on the two following issues:

1) Ethanol can dissolve plastic and create deposits

Ethanol is an excellent solvent and drying agent that dissolves old gum and varnish deposits from the gas tank and fuel lines.

However, ethanol can also dissolve plastic and create deposits, like those seen in the carburetor bowl shown here.

Carburetor

Honda states that the dissolved material can clog filters or pass through and leave deposits on fuel injectors, fuel pumps, fuel-pressure regulators, carburetor jets, intake tracts, valves and valve guides.

The result can be a lawnmower, snowblower, chainsaw or other equipment that won’t start or runs poorly.

Small-engine manufacturer ECHO agrees, stating in its warranty that these deposits can lead to poor engine performance; loss of power; overheating; fuel-vapor lock; improper clutch engagement caused by increased engine idle speeds, which allows cutting attachments to turn while the unit is idling; and premature deterioration of fuel lines, gaskets, carburetors and other engine components.

2) Ethanol and water don’t mix

Small-engine manufacturers have spent considerable time studying the relationship between ethanol and water.

ECHO warns that ethanol will absorb a small amount of moisture and stay in suspension within the gasoline for a while.

However, the ethanol will only absorb up to three-quarters of an ounce of water in a gallon of gas before it reaches its saturation point. Once the ethanol has absorbed enough moisture to reach its saturation point, phase separation occurs.

Phase separation means the ethanol and absorbed water drop to the bottom of the fuel container since it is heavier than the gas and oil, leaving the gasoline and oil mix to float on top of the tank.

Ethanol problems
Phase separation occurs when ethanol/water mixtures fall to the bottom of the fuel container, leading to potentially damaging lean-burn conditions.

Most operators never notice water in the can when they refuel their equipment. The end result is often a carburetor ruined with rust and corrosion. These repairs can be costly and are not typically covered by warranty.

Stihl stresses that the layer of gasoline left floating on top has a lower octane level than the original ethanol-gasoline blend, which can result in unstable engine operation, power loss and major engine failures.

Ethanol’s affinity for water explains why so many ethanol-related problems surface in the marine industry.

In fact, some marina personnel say up to 65 percent of their service orders are attributable to fuel-system problems.

Combating ethanol problems

Although some fuel additives on the market claim to reverse the effects of phase separation, there’s no way to reintegrate gasoline and ethanol once they’ve separated. Instead, it’s best to prevent it.

One solution is to use non-oxygenated, ethanol-free gas in your small engines. It costs a little more, but it eliminates problems associated with ethanol.

Another solution is to treat every tank of fuel and container of gas with AMSOIL Quickshot. It helps keep water molecules dispersed in the fuel to prevent phase separation. It also cleans varnish, gums and insoluble debris while stabilizing fuel during short-term storage.

AMSOIL Quickshot

Quickshot was tested in fuel containing 10 percent ethanol. Controlled plugging of injectors showed a 70 percent flow improvement, while oxidation stability improved 44 percent over untreated fuel. It addresses ethanol-related problems and helps keep your small engines running strong.

Regardless whether you’re pro- or anti-ethanol, we can all agree on the importance of taking care of our small engines.

Updated. Originally published: July 12, 2017

Comments

  1. I use nothing but ethanol free fuel because I was experiencing fuel problems in all of my power equipment. Since switching over, I have had no problems with my mowers, snow thrower, generator, tillers, or weed whips!

  2. We run 25 Honda eight hp outboard motors in a marina rental fleet. Had to rebuild ALL the carburetors on all of these BRAND NEW motors due to ethanol swelling rubber in float bowls. The mercury outboards (40hp) also suffered fuel pump damage in brand new motors.

  3. My neighbor just bought a new weed whacker, He read the instruction book cover to covered and it states to use “fresh gas” at all times. Didn’t go in to why fresh gas all the time. So I looked up phase separation of alcohol blended fuel. Now this is where it seems to differ, depending on who is blogging, the alcohol separates from the fuel with in 60 to 90 days. Why it separate is because alcohol absorbs moisture like a sponge. The longer fuel sits the more it absorbs…till it can’t anymore. I tried phase separating my lawn equipment fuels this summer, both lawn mower and edger/weed whacker…it was messy but it did help with keeping my fuel fresh longer. Its not for everyone and I’ll go back just buying a gallon at a time and treat just what I need. I know if its on a larger scale and my engines sit for many days at a time then I’d run them dry and keep buying fresh fuel as needed.

  4. The negative comments made about ethanol in the story and responses above are all ridiculous lies. If Andy Arendt ever knew anything about internal combustion engines and fuels he forgot it all.

    Why Do Small Engines Suffer From Ethanol Problems? Hint, they don’t!
    http://www.theautochannel.com/news/2015/09/01/140446-why-do-small-engines-suffer-from-ethanol-problems-video.html

    Famous Manufacturer of Anti-Ethanol Additives Proves Ethanol’s Safety and Benefits
    https://www.theautochannel.com/news/2019/08/10/677743-is-it-is-or-is-it-ain-t-famous-manufacturer.html

    Automotive Aftermarket Saturated with Snake Oil Engine Additives
    https://www.theautochannel.com/news/2019/08/16/680489-automotive-aftermarket-saturated-with-snake-oil-engine-additives.html

    1. You have some valid points, however, ethanol does cause problems for small engines. I have witnessed this on several pieces of equipment and I have since made changes to my equipment maintenance.

      You can’t say that it doesn’t for everyone because unless you have seen every single piece of equipment and verified that it wasn’t the ethanol then you’re making an assumption based on invalid and incomplete information.

    2. Marc Rauch I beg to differ. I used gas with 10% ethanol in my brand new 2000 Watt Harbor Freight generator. The generator ran perfectly at first but began idling roughly and surging within a few months. I used several fuel conditioners and cleaners trying to clean out the fuel system. Nothing worked. I finally drained the ethanol fuel, replaced the carburetor and switched to ethanol free gas and the generator runs perfectly again. NEVER use ethanol contaminated gas in small engines!!!!

  5. Thank you very much for the request Christian,
    The merits of ethanol stem from its environmental benefits as an oxygenate Vs alternatives like MTBE, its solvent properties are excellent, as well as its ability to displace water. However, these same properties can also create issues related issues related to deposits and corrosion. Lastly, ethanol has 28% less energy density than gasoline.

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