Gasoline from the “pump” in NJ has ethanol in it. Ethanol is an alcohol added to gasoline to reduce petroleum usage by volume. For example, most gas stations in NJ use a blend of 90% gasoline and 10% ethanol. Thus reducing gasoline usage by 10%. Ethanol for use at the pump is primarily derived from corn which is classified as a renewable resource. This all sounds good as far as reducing fossil fuel usage but has plagued the small engine repair community in ways that were never intended.

Ethanol attracts water! As a result, over time, the ethanol/water mixture becomes saturated enough to move it to the bottom of the tank due to the added weight of the water. I’m sure you already know that oil(gas) and water don’t mix. I’m also sure that you realize that oil(gas) is lighter than water. The result is that you have a layer of water-saturated-alcohol at the bottom of the tank and the gasoline is floating on the top of the tank.

“Phase separation occurs in E10 gas when it absorbs only 0.5% of water (3.8 teaspoons) per gallon of E10. When 0.5% of water is absorbed into the ethanol-gasoline blend, the bonded water and ethanol will separate and dissipate from the rest of the gasoline. The water and ethanol will drop out of the gas and you will be left with a layer of water on the bottom of the tank, a layer above that of ethanol/water mix, and above that a top layer of gasoline that is now 3 octane lower than it was when it was mixed with the higher octane ethanol.

The remaining components of this phase separated gas are not re-mixable and should be discarded. Phase separation is a significant problem when storing E10 more than 100 days.” OR LESS.

Ethanol has the ability to hold contaminants in suspension. What this means is that, rather than having solid contaminants lay harmlessly on the bottom of the fuel tank, those contaminants are lifted into suspension and carried into the various fuel system components. As the alcohol evaporates, those solid contaminants are left behind to clog up the finite orifices of things like carburetor jets.

As a result of this, engines, especially older ones that were never designed to use fuels mixed with ethanol, are plagued with problems. This is especially true when they are stored for long periods. Smaller displacement engines are more prone to the effects of this due to the smaller size of the orifices of their internal fuel related parts (carburetor jets, etc). The smaller the orifice the more easily it will clog from a contaminant.

What can the average person do to mitigate this issue???

If you ask this question online, the predominant response is to ensure that you don’t store ethanol blended fuel for long periods. Well, how does one accomplish that?

1) Use ethanol free fuels (best method). This may not be so easy or financially appropriate. Ethanol free fuels are only available “in-store” in NJ. You can get ethanol free gasoline and 2-stroke at big box stores. They are sold in small cans and at an increased premium, approx $25.00/Gal. You can also get ethanol free gasoline “at the pump” in PA for approx $5.xx/Gal.

2) You could drain the entire fuel system any time you suspect that the equipment might sit idle for a long period of time. BUT, how do you know when you’ll be storing? Are you able to predict the future? Also, most machines do not have an easy way of draining the fuel system…..even for a mechanic. Is the average user capable of doing this?

3) You could have a fuel drainage and shut-off system installed on your equipment. (my preferred method) This would involve a simple set of valves to allow you to easily drain the fuel in the tank and then burn off the leftover fuel in the carburetor leaving the fuel system vacant and thus avoiding the pitfalls of ethanol treated fuels. This is probably the easiest and preferred method for the typical equipment user. Unfortunately this requires a knowledgeable technician to install and is not a factory set-up in most instances.

4) Utilize an existing, built-in, fuel shut-off. The shut-off, if appropriate for ethanol fuels, will keep the fuel out of the carburetor, IF the carburetor is properly drained. (bare minimum method) Close the fuel shut-off valve and let the machine continue to run until the carburetor is empty and the engine stalls. It’s not a perfect method but it is a BIG step that’s easy to do. This will minimize, but not entirely eliminate, unnecessary buildup when storing for a machine for long periods.

So, in a nutshell, avoid using ethanol when possible, drain the fuel system when possible, and as a bare minimum, use up any fuel left in the carburetor before storing.