Ethanol In Gasoline Reportedly Wreaking Havoc On Small Engines

I know that many of you are having problems with your motors.  Mowers that only run for 15 seconds, tractors that won’t start at all, snow blowers that will only run on full choke. Fuel lines and primer bulbs melting. Carburetors full of varnish and crud.  2 cycle string trimmers and leaf blowers the seize up and die.  Many of you are blaming “shoddy” workmanship from companies like Craftsman, John Deere, MTD and others.  But, who really is to blame?

In addition, the whole lawn and garden industry has been talking about the new E-15 ethanol issue and with the 2011 emissions regulations changes it’s time to let you know what is up and how all this affects you.

Here are three articles about Ethanol Blended Fuel and how it affects you and your small engines. In another article I will specifically talk about the new emissions equipment on your new 2011 motor and how it affects you. I’ll also write about what you need to do to keep your equipment running.

BGS Engine Clinic

Motor Moonshine – That’s what I like to call Ethanol Blended fuels.  – It’s simply corn alcohol blended into gasoline. Too much of it, and your motor gets drunk and does funny things…  Also known as E-10, and these days, E-15, and may also be known as Ethyl Alcohol, Grain Alcohol, or just plain ol’ Moonshine mixed in your gas. Whatever it is called, it can be deadly for your small engines. With the new ruling from the U.S. EPA, the formerly manageable issue of E-10 blended fuel can become a real problem of E-15 blended fuel.

Most all OEM’s will have warranties that state that warranty is void if equipment is operated on fuel blends with greater than 10% ethanol. Up until October 13,2010, this was never really a problem – since the federal limit  on ethanol blends was 10%. However with the new EPA ruling, this means you will have to be even more vigilant at the pump, and watch out for any fuels that may be labeled as E-10 or E-15.

Ethanol has reduced energy potential compared to plain gas, lower boiling point than gasoline, and readily mixes with water (it is, after all, basically just fermented corn mash with the water boiled out of it).

Ethanol can cause rubber parts to swell, dry out, and break apart – fuel lines rot out from the inside (De-Lamination), carburetor parts swell up and block passages, diaphragms become porous, o-ring seals begin to distort and leak, etc.

Prevention is only possible by buying clean, fresh fuel, and do not buy more fuel than you can use in a couple months. Fuel stabilizers are available that helps keep fuel stable for longer periods, but they must be added *as soon as* the fuel is purchased.

Ethanol fuel as purchased at the gas pump may contain up to 15% ethanol content. Refineries may blend in ethanol to increase the octane rating to meet federal requirements and guidelines. So, for example, regular gasoline may be refined to 84 octane, and then ethanol blended in to bring the octane rating to 87. This is important to keep in mind for the rest of the article. Octane rating is a measure of how much pressure gasoline can be compressed before it spontaneously combusts. The higher the octane rating, the more pressure it can handle.

This is important to all gasoline powered engines of all kinds – when fuel is drawn in to the combustion chamber, it is then compressed, and the spark should ignite the mixture. When the octane rating is too low, the fuel – air mixture may spontaneously ignite before it is supposed to – known as detonation or pre-ignition. This can be deadly for any engine. In severe cases, prolonged detonation can punch a hole through the piston, it also contributes to overheating, and severely reduces engine power. in pull-start engines, detonation can be severe enough to literally break your fingers, hand, wrist,etc, if you have a good grip on the starter handle!

Ethanol fuel also does not burn as well (which is why they use it to improve octane rating to begin with), it does not burn as hot, and has less volatility. It has about 30% less potential energy than gasoline alone. This results in reduced power, reduced fuel mileage – about 3% less – (funny, ain’t it? – Government wants to increase mileage and then says refiners can blend fuel that reduces it!! go figure.)  In any case, this magnifies any issues your engine may have with performance – an engine that runs marginally on straight gas, may have real issues when running on ethanol blended fuel. This may result in needing more frequent tune-ups, maintenance, or even overhaul or replacement .

Ethanol also has a lower boiling point than regular gas, which can often result in vapor lock in the heat of summer, and even when engines overheat. It’s a double-whammy since ethanol can contribute to engine overheating in the first place.

Replacement engines are already engineered and designed to run on up to 10% ethanol, but at this time, there are very few, if any, small engines that are designed and capable of running on fuel greater than 10% ethanol blend.

Modern engines are engineered and designed to run on modern fuels, up to 10% ethanol – The aluminum alloys, the rubber and viton gaskets, the ignition systems, pistons, rings, valves are all engineered to combat the effects of 10% ethanol. (More info on these specifics will be found as you read along..)  – However with this new ruling, which the OPEI (Outdoor Power Equipment Institute) and most all manufacturers were against, for various reasons, including insufficient testing on outdoor power equipment, even brand new equipment is vulnerable to this issue.

Using E-15 fuel in power equipment that is under warranty can, and will void the warranty.

Ethanol blended fuel, if it is fresh and clean (and by fresh, we mean since the time it was blended at the refinery, not from the time you buy it at the pump!)  can safely run in most engines..

Even E-15, IF, and this is a big if – if regular, aggressive maintenance is done – fuel system cleaning and inspection, replacing the fuel lines, filters and rubber parts on a regular basis (annually or more frequently)  – This is a lot to ask for most equipment owners.

What Ethanol does to power equipment:

  • Ethanol is Hygroscopic (absorbs water) – the combination of moisture and ethanol is highly corrosive to aluminum parts.
  • Ethanol can cause rubber parts to swell, dry out, and break apart – fuel lines rot out from the inside (De-Lamination), carburetor parts swell up and block passages, diaphragms become porous, o-ring seals begin to distort and leak, etc.

Ethanol blended fuel that is no longer fresh (even if you just bought it!) can cause a multitude of issues.

When ethanol blends with enough water or moisture (as little as 0.5%) , it experiences what is called phase separation – it becomes heavier than the gas, and drops to the bottom of your fuel tank or carburetor. with most power equipment, that often results in no-start because it’s suddenly trying to run on a mixture of water and alcohol, instead of gasoline. Good thing- it would ruin your engine otherwise.

One of the indicators that your fuel is absorbing water is easy to see – as ethanol absorbs moisture, the gas becomes hazy and cloudy, until there is enough water absorbed for phase separation. Using this little fact you can tell if gas contains ethanol by taking a gas sample and adding a little water, shake it up and either gas becomes hazy after the bubbles settle, or you have a thicker water line at the bottom of the sample than you started with (because it has phase separated, and dropped to the bottom – thats how the testers work).

Even without that, phase separation is a nasty thing –  remember when I explained above how ethanaol boosts octane rating? Well, with the ethanol separated from the 87 octane gas, you’re now running on 84 octane fuel, and an engine with even some age can experience detonation and performance problems. – this is one reason why manufacturers will void the warranty on power equipment when it is run on fuel with greater than 10% ethanol content.

Specific to 2-cycle engines, this is even worse news- as mentioned before, water or moisture absorbed into the gas results in phase separation. When this happens it also sucks down the mix oil as well, so if you were to fill up your chainsaw with gas, use it a little bit, and then let it set long enough, if phase separation occurs and takes the oil with it, even if  you shake up the gas before you start it, chances are good that your 2-cycle equipment will be running on what is basically straight gas, resulting in severe engine damage, and very expensive repairs! (note: you can test 2-cycle gas in the tester, and the results you see will be eye-opening!)

Because ethanol does not burn as well, and yet the fuel system delivers the same amount of fuel, your engine will tend to run a bit “lean”, and this is often a cause of engine overheating, which results in premature wear on all the parts, valve burning, spark plug life is shortened, and often causes blown head gaskets. (overheated aluminum expands and “squishes” the gasket beyond its recovery limit, so the next time it runs, the gasket does not seal completely, allowing combustion gasses to burn through the gasket)

This can also be a problem in cars and 4-wheelers, and even some higher end small engines – these may be equipped with oxygen sensors, and the extra ethanol burned can “fool” the oxygen sensor (O2 sensor) into thinking there’s more oxygen present in the exhaust, which makes the control computer think the engine is running rich. When this happens, the control computer commands the fuel delivery (injectors) system to inject less fuel, causing a lean running condition as noted above – if your engine hesitates on acceleration, or “gallops”, this can be one of the causes (Other causes include dirty or plugged fuel passages in carburetor, and air leaks around gaskets and o-rings all of which can be caused by, or contributed to by, ethanol blended fuel)

Another issue that can occur is with equipment that has electric fuel pumps – Since ethanol conducts electricity better than gasoline, this can contribute to a condition known as electrolysis when the fuel pump is running – basically the same chemical reaction that occurs in a battery – tiny atoms from aluminum may come off and attach to copper parts, or bits of copper corrode off and attach to steel parts, in a nutshell – electroplating. When the fuel pump is not running, but electrical current is present (key on, engine off, for example) there can be galvanic reaction occuring – its a reaction between dissimilar metals resulting in sand-like, powdery deposits forming – basically aluminum corrosion, but it affects other metals as well – which can plug up your fuel filters, carburetor passages, etc.

Preventing problems with modern ethanol blended fuel is not too difficult. for some people they may never experience problems, since they already don’t buy more gas than they use in a month or so, they take care to keep it in a clean, sealed gas can, avoiding moisture absorption.  For other people, it may require some changes to their gas buying habits – buy less gas, more frequently, and buy from a busy gas station (one that gets fresh shipments every week or so, or more often, is ideal). If you don’t want to buy less gas more often, then you really need to invest in some fuel stabilizers such as sta-bil, for example. Do not use dry gas – it contains alcohol too. Dry Gas is actually a brand name, and generically is known as gas line anti-freeze – read the bottle label – if it says isopropyl alcohol or ethyl alcohol (in fact, any type of alcohol) you should not use it.  Buy fresh gas and immediately add fuel stabilizer.

Fresh ethanol blended fuel remains stable roughly 45 to 60 days in summertime, but as it degrades, initially the more volatile parts of the fuel will evaporate first (which can cause harder-to-start engines), followed by the less volatile hydrocarbon compunds (the “meat” of the gas) to oxidize into other chemicals (Varnish, Gum, etc) – your fuel starts to become dark and cloudy and you may begin to notice a very distinctive, very strong varnish-like odor in the gas. When it gets this bad, an engine is almost impossible to start, and any burned fuel coming from the exhaust will have that strong, distinctive varnish-y odor to it.

Fuel stabilizer is not a magic bullet – if you add it to old, stale gas, you just end up with old, stale gas that stays old and stale much longer! It will not magically make “bad” gas good again.

Fuel should be stored in D.O.T or E.P.A. approved gasoline containers and keep the caps on tightly. Store fuel in a cool, dry place. If you store it in your garage, keep the containers out of sunlight – The sun warms the fuel, causing it to expand, and the gas cans will “vent” the pressure.. When it cools down, it draws in moisture-laden air, and condensation forms on the walls of the fuel can, which, obviously, is moisture that gets absorbed by any ethanol present in the fuel.

So, how can you tell if gas has ethanol blended into it? Short of sending samples to a laboratory (expensive) , the only other way is to use an alcohol content tester. With this simple tester, you add water to the fill line, then fill the tester the rest of the way with gas, shake it up good, and leave it to settle for 10 minutes or so. When you check again, you may note the water line is raised. this means the alchohol has mixed with water and phase separated to the bottom. The fuel tester will have a 10% line which, if the water line is up to or above that line, you’ve got fuel with greater than 10% ethanol.

Best advice in that case is to take the gas to an oil collection facility for disposal.  (dont just dump it out! it’s bad for the environment, and it is also illegal.. it’ll also burn brown patches into your lawn if you happen to dump it there.) If it was freshly purchased fuel, however , you should be fine for a month or two, but it is still advisable to add fuel stabilizer.

From Briggs & Stratton Newsroom

Briggs and Stratton Warns Consumers New Ethanol e-15 Will Harm Small Engines


MILWAUKEE, WISCONSIN- October 25, 2010 – Briggs & Stratton advises outdoor power equipment users to be aware of a new fuel with a higher level of ethanol that could harm small engines. Recently, the Environmental Protection Agency (EPA) approved higher levels of ethanol (E-15 or 15% Ethanol) in gasoline for use in only 2007 and newer automobiles and light trucks.

All Briggs & Stratton small gasoline powered engines are designed to run on up to E-10, or up to 10% ethanol.  Use of higher levels of ethanol will affect engine performance and longevity, permanently damage the engine and void manufacturer’s warranty. The Operator’s Manual clearly explains what fuels can be used to ensure a properly functioning product.  Consumers should also pay close attention to the gas pumps at local filling stations.  Some may offer both E-10 and E-15 or have blender pumps that dispense mid-level ethanol fuels for “flex-fuel” automobiles.  With an estimated 80 million walk behind and riding lawn mowers, valuing almost 50 billion dollars in garages all over the U.S., the financial burden to consumers is astronomical.

“Briggs & Stratton supports efforts towards energy independence and the use of biofuels; however, our products were not designed to run on any fuel containing ethanol over 10%.”  said Laura Timm, Communications Director at Briggs & Stratton. “We are deeply concerned for consumers who own our products and who may inadvertently put E-15 in their products, ultimately causing damage and voiding their warranty.  We are strongly encouraging the EPA to educate consumers on the adverse impacts E-15 will have on small engines and to put methods in place for consumers to preventmisfueling.”

Briggs & Stratton Corporation, headquartered in Milwaukee, Wisconsin, is the world’s largest producer of gasoline engines for outdoor power equipment. Its wholly owned subsidiary Briggs & Stratton Power Products Group LLC is North America’s number one manufacturer of portable generators and pressure washers, and is a leading designer, manufacturer and marketer of lawn and garden and turf care through its Simplicity®, Snapper®, Ferris® and Murray® brands. Briggs & Stratton products are designed, manufactured, marketed and serviced in over 100 countries on six continents.

Deanna Zabel
Briggs & Stratton Corporation


If you’ve been having trouble with your small gasoline power equipment lately, MSNBC reports that you’re not alone: Small-engine mechanics nationwide are seeing a spike in engine damage they claim is attributable to the increasing use of ethanol in gasoline. We’re not talking about E85 here either; apparently, it’s the much more common (and in some places ubiquitous) E10 blend, which is 10% ethanol and 90% gasoline, that technicians are blaming for gummed-up carburetors, internal rust and lubrication issues.

Of course, ethanol trade groups are claiming their extensive testing showed no adverse effects from running E10 in small gas engines. But the mechanics’ descriptions of what they’re seeing, coupled with the known properties of ethanol, make for a compelling argument. Since ethanol combines readily with water, gasoline containing ethanol easily transports that suspended water into the engine. Once inside, the water can gum up carburetors and cause rust on key components, leading to rapid wear and eventual breakdown.

On two-stroke engines, the potential for damage is even more acute. Small two-strokes carry their lubricating oil suspended in the air/fuel mixture. Mechanics are reporting that the presence of water in that mixture, carried by ethanol, is causing the lubricating oil to disperse before it reaches critical engine components. Since an oil-starved engine doesn’t last long, customers are reporting mechanical failure after only a season or two of use.

And heads up to you maintenance junkies: draining the tank every season won’t prevent problems. The deposits and damage apparently occur independently of the “gum and varnish” issues previously associated with old, stale gasoline. So what can you do? Read pump labels carefully, and if you can find ethanol-free gasoline in your area, buy it. If not, there isn’t much you can do except hire a lawn service and let their equipment take the abuse.

The Outdoor Power Equipment Institute (OPEIweighed in as well, saying that it has serious concerns with a “premature rush” to 15% ethanol (E15) or other mid-level fuel blends.

The fact is that the use of E15 and higher levels of ethanol is a complex issue, and it can’t be rushed by efforts that overlook the impacts on consumer safety and economic interests. OPEI fully supports congressional efforts to increase the use of cellulosic fuels. We can design products to run on higher levels of ethanol.

—Kris Kiser, Executive Vice President at Outdoor Power Equipment Institute

However, Kiser said, existing small-engine equipment will likely experience performance irregularities and possible failure. In a new report cited by OPEI, independent researcher Dr. Ron Sahu critiqued the DOE report (above) that tested a small sample size of legacy vehicles and small non-road engines. DOE’s engine test results indicated that, for the off-road, non-vehicle engines:

  • Engine exhaust temperatures rose to an extent that may cause premature engine and equipment failure,
  • Safety hazards increased due to unintentional clutch engagement caused by high idle speeds,
  • Products were damaged to the point they could no longer operate, and numerous adverse operational issues arose – such as erratic engine and equipment operation, stalling of engines, and dramatic power reduction.(DOE also noted that the effect of E15 and E20 on the durability of smaller, less expensive residential engines (e.g., line trimmers) was not clear given that a number of these engines failed regardless of fuel type.)In his remarks, Gen. Clark noted that the waiver request would not impact small engines since gas stations would still be able to sell lower blends of ethanol, including gasoline with zero ethanol (E0).

Go here to see all of my 2011 reviews:

My 2011 Reviews.  You can find larger and smaller mowers from this list.


  1. Bruce Kurtz April 25, 2014
    • Paul Sikkema April 25, 2014
  2. dave February 15, 2013
    • Paul Sikkema February 15, 2013

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