The issue of ethanol in fuel is definitely not limited to Yamaha but can affect all brands of snowmobile. We're putting this information here because Yamaha was nice enough to share the technical aspects of ethanol and the potential harm it can cause snowmobile engines. Preventative maintenance doesn't get any more important than this.
For purposes of this section, we're referring specifically to E-10 fuel, which is gasoline containing 10 percent ethanol.
Patrick Busler, an instructor/developer of technical training in Yamaha's service division, pointed out that fuel with a content of up to 5 percent ethanol does not have to be reported. He added that Yamaha engines can detect as small as 3 percent ethanol content in fuel.
We've all seen signs at the gas station on the pumps which say, "May contain up to 10 percent ethanol." Sometimes gas stations don't even know if their fuel has ethanol in it.
That can make it tricky to find a station that does not have ethanol in its fuel. E-10 fuel, a mixture of 90 percent gasoline and 10 percent ethanol, has been introduced into various regions of the United States and, in many locations, E-10 fuel is the only type available.
The Environmental Protection Agency (EPA) has implemented Ground Level Ozone Air Quality Standards. Part of the EPA's strategy to meet these standards requires the addition of fuel oxygenates to gasoline to improve the internal combustion process. Ethanol or MTBE (Methyl Tertiary Butyl Ether) are approved fuel oxygenates.
Ethanol has a very high octane rating and when mixed with low octane unleaded gasoline, increases the octane level of unleaded gasoline. Ethanol also has some less desirable properties that are explained below.
MTBE does not have negative effects on engine fuel systems but does have some negative environmental issues; it does not biodegrade easily and is a suspected carcinogen. MTBE contamination from leaking underground fuel storage tanks has been detected in groundwater supplies. Many states are now prohibiting use of MTBE.
The following questions and answers provide important information regarding the use of fuel containing ethanol.
Q. Are Yamaha engines compatible with E-10 fuel?
A. Yes, all current models as well as most engines built since the late 1980s have been designed with fuel system components that are tolerant to fresh fuel containing ethanol up to 10 percent.
Q. Can I use fuel with a higher percentage of ethanol, such as E-15 or E-85?
A. No, all of the negative issues discussed below will be increased and may cause major damage to the engine.
Q. What are the properties of ethanol in E-10 fuel that make it less compatible with fuel systems than straight gasoline?
A. Ethanol has several properties that contribute to fuel system issues:
Ethanol is hygroscopic (i.e., it has a strong attraction to moisture).
Ethanol is a strong cleaner (solvent).
Ethanol produces less energy (BTUs) than an equivalent unit of gasoline.
Q. What issues are caused by ethanol's attraction to water?
A. Ethanol molecules have a stronger bond to water molecules than to gasoline molecules. In the absence of water, ethanol and gasoline molecules will bond. When water is added to E-10 fuel, the bond between the ethanol and gasoline will weaken. When the percentage of water in E-10 fuel reaches approximately 0.5 percent, the bond between the ethanol and gasoline molecules will break and the ethanol molecules will attach to the water molecules. This is called phase separation. The ethanol and water molecules settle to the bottom of the fuel tank, forming a distinct layer of water and ethanol on the bottom and gasoline without ethanol on the top. As little as 1.6 oz. of water can promote phase separation in 2.5 gallons of E-10 fuel. The result would be 33.6 oz. of unusable ethanol and water mixture on the bottom of the tank.
Q. What happens when phase separation occurs?
A. Several things happen:
Fuel for the engine is drawn from the bottom of the tank. An engine will not run properly, if at all, on ethanol and water.
The ethanol and water mixture is very corrosive to some metals and can cause corrosion or rust in the fuel tank and damage internal engine components.
The remaining gasoline, without ethanol, will have an octane level below the original E-10 fuel's octane level, approximately 2-3 points lower. This octane level may be below the requirements of the engine.
Q. Can phase separation be reversed?
A. No, there are no additives or processes that will recombine phase separated ethanol and gasoline.
Q. Can I use the gasoline remaining after removal of the phase separated water and alcohol?
A. No, the remaining gasoline, without ethanol, will have an octane level below the original E-10 fuel's octane level, approximately 2-3 points lower. This octane level may be below the requirements of the engine.
Q. What issues are caused by ethanol's strong cleaning (solvent) properties?
A. It is normal for gasoline to leave varnish deposits and for surface corrosion to occur inside the tanks and pipes used for fuel transportation and storage: rust on steel and oxides on aluminum. Ethanol will clean any varnish as well as rust and oxides from any surface it contacts. Gasoline without ethanol does not clean the varnish, rust or oxides. Since ethanol is added at the distributor facilities, it will clean any storage pipes and tanks, truck tanks, gas station storage tanks and your engine fuel systems. The amount of material cleaned from all of these systems can quickly exceed the filtration capacity of filters located in fuel systems, resulting in restricted fuel flow. If these filters are not replaced, engine performance is reduced and potentially, damage to the engine can occur.
Q. What issues are caused by ethanol's lower energy content (BTUs) than an equivalent unit of gasoline?
A. E-10 fuel will produce approximately 3 percent less power than gasoline. This is not enough to be noticed in most applications.
Q. How long can E-10 fuel be stored?
A. There are many different opinions concerning how long it is okay to store any fuel (E-10 fuel or gasoline). Two weeks, 90 days, ???, before losing the properties that are required for proper and safe operation of your engine. There are too many variables, such as the age of fuel when purchased, temperature, humidity, use of stabilizers and the type of storage containers, to accurately predict how long.
Q. What can I do to reduce or prevent issues with E-10 fuel?
A. Total prevention of issues may not be possible but there are steps you can take to minimize the occurrence and severity of the negative effects of E-10 fuel.
Remove any accumulated water from your fuel tank periodically.
Avoid mixing E-10 and MTBE gasoline blends. Mixing may cause precipitates to form, which can clog filters.
Do not drain a used filter and reinstall. Contaminated fuel can enter the filtered side of the filter while draining.
Buy name brand fuel.
Buy fuel from the same source if possible.
Buy fuel from stations that have newer, cleaner storage tanks.
Regularly use Yamaha Fuel Stabilizer to retard fuel aging.
Note: Stabilizers do not help fuel that has already aged. Stabilizers are the most effective when immediately added to fuel fresh from the gas station.
Ensure stabilized fuel is circulated through all of the engine's fuel system components prior to storage.
Drain fuel from carburetors that have open air vents.
Store fuel tanks approximately 7/8 full, minimizing the amount of air space above the fuel inside the fuel tank.
Note: Storing completely full may allow some fuel spillage as the fuel expands during hot weather. Do not attempt to seal a vented fuel system. The inability to vent could cause damage to the fuel tank or other fuel system components.
Minimize the time fuel is allowed to age in your fuel tank or other storage containers.
Do not attempt to use fuel with ethanol content higher than 10 percent. If in doubt of the ethanol content of the fuel, test the fuel to verify the amount of ethanol is not higher than 10 percent. Inexpensive test kits are available. A web search will provide many sources. Just type in: E-10 fuel test kit.