Ethanol Damage Up Close

See Ethanol Damage UP CLOSE!

Posted April 6, 2015 by 44 Comments

All this talk about ethanol and bad gas leaves many homeowners and landscapers constantly worried about refueling their power equipment.

Repair shops know it all too well, how ethanol and stale gas affects your equipment. They’re seeing the damage every day.

But for those who want to see it to believe it, here’s your chance. Check out the effects of ethanol up close!

Step into the shoes of a power equipment repair technician as we dissect a lawn mower and generator carburetor.

You’ll see with your very own eyes how ethanol and stale gas can clog and corrode the carburetor and fuel system components.

Crusty Deposits – Deterioration

Carburetor Deterioration from Ethanol

Ethanol has a tendency to absorb water. The water moisture, along with ethanol, slowly deteriorates the metal parts of the fuel tank and carburetor.

The white crusty deposits you see collecting on this generator carburetor are the deteriorated metal particles.

Corrosion Buildup and Water in the Carburetor Bowl

salty deposit buildup in carburetor bowl from ethanol

As ethanol eats away at the metal parts, as well as the rubber and plastic parts of the fuel system and carburetor, it leaves those corroded particles in the carburetor bowl.

These particles can clog the carburetor jets, causing extremely poor engine performance. The particles can even enter your engine’s cylinder!

Gummy Varnish Deposits

ethanol damage

Old, stale gas degrades and breaks down over time, forming gummy varnish deposits that eventually harden and clog the carburetor jets too. Notice the black varnish deposits forming on this lawn mower carburetor.

*If your fuel smells sour or smells like nail polish, it’s stale! Don’t use it.

So there you have it, ethanol damage up close and personal. Keeping your gas fresh, properly treating it with a fuel stabilizer, or buying strictly ethanol-free fuel, is as important as that regular oil change every year.

Hopefully these images weren’t too disturbing for you. But at the very least, you’ll think twice about refueling with stale gas. Right?

Watch this video on how to use ethanol fuel in power equipment.


  1. R Regan
    on August 13, 2013 at 11:52 am

    How much time is required for the ethanol gas to do the damage shown in your pictures? I have never seen a carburetor in that condition with ethanol gas left over in it during the winter (4 to 5 months). RPR

    Reply to this Comment

  2. Chuck
    on August 13, 2013 at 12:36 pm

    I let the gas in my generator dry up and it rusted the tank so bad I had to change it.

    Reply to this Comment

  3. karen russell
    on August 13, 2013 at 1:43 pm

    yea, very informative. people have heard of the terms you are describing, but don’t really have a mental picture to go with it, i think that the photos connect them together very well. along with advice about not buying it to begin with, go ahead and pay a little more for good fuel because in the long run, you are gonna pay dearly. thanks alot

    Reply to this Comment

  4. Ivan Copas
    on August 13, 2013 at 1:48 pm

    My one year old Poulan string trimmer would not start this spring.
    I determined it was not getting gas although the tank was half full.
    I finally removed the carburator and found a little filter screen, about a quarter inch in diameter coated with a brownish film. I was able to clean this with carb cleaner and change the gas I had left in the tank. Then all was well.
    I’m going to drain the fuel this fall before I store the unit.
    Ivan Copas

    Reply to this Comment

    • Mick
      on November 4, 2016 at 9:54 pm

      Hi, it’s better to leave fuel in over storage time so the fuel lines don’t break up.

      Reply to this Comment

  5. Larry
    on August 13, 2013 at 1:53 pm

    I discovered this after two repetitive years of replacing carburetors on my chain saw, generator, and lawn mowers. This ocurred even though I used a fuel stabilizer. Then I found a place that sold Ethanol free gasoline last year. No more problems!

    Reply to this Comment

  6. Pete Klinkhammer
    on August 13, 2013 at 2:27 pm

    I live up in the Ozark mountains.Lots of rocks and clay.Most of my mowers tiller chainsaws are old and used but I put some trearment in every tank of gas and all my old junk runs fine.I have used several things but Startron works well.Allso marvel mystery oil also helps with things like my 65 Dodge d ioo pickup.Trearment stuff cost money but is cheaper than a carb,or other repairs.

    Reply to this Comment

    • Turner Anderson
      on August 14, 2013 at 9:25 am

      Yes, definitely use a fuel stabilizer. Some people make the mistake of adding a stabilizer to gas that’s already gone bad. Won’t be much help there. Thanks for sharing Pete!

      Reply to this Comment

  7. George McGarvey
    on August 13, 2013 at 2:34 pm

    Good sound information about ethanol in gasoline and what damage it can do to engines.

    Reply to this Comment

  8. Shirley Smith
    on August 13, 2013 at 3:38 pm

    Thanks for this article! All of my lawn equipment, whether it be the trimmer, riding mower, push mower or blower runs terribly with the ethanol content in gasoline. A neighbor finally told me about a gas station “off the beaten path” back in the farmlands, that sells gas with no ethanol. I make a trip out there every few months and fill up all my gas cans, and the difference in the running of my equipment now is quite noticeable. The ethanol free gasoline costs over $4.00 per gallon (I’m in Mississippi), plus the cost of the 50 mile round trip out to get it, but it’s worth it! I’m sure I have done damage to my equipment prior to finding this gas that has no ethanol, but hopefully it won’t continue now to deteriorate the metal parts. Your article explained exactly what ethanol is doing to lawn equipment and I really appreciated the opportunity to read it.

    Reply to this Comment

    • Turner Anderson
      on August 14, 2013 at 9:32 am

      A lot of people are finding the benefits of paying a little extra for ethanol-free gas. Hope your 50 mile round trips continue to serve you well. Glad you liked the article Shirley.

      Reply to this Comment

  9. Mr. Jeffries
    on August 13, 2013 at 4:54 pm

    It is such a good idea to put a fuel shutoff on all of your large equipment. Shut the fuel off when you are done, and allow the engine to run until it shuts off from lack of fuel. Small equipment such as leaf blowers and tillers should be dumper of fuel, then ran until they quit as well… Great article though. I plan on using this website in one of the classes that I teach.

    Reply to this Comment

    • Turner Anderson
      on August 14, 2013 at 9:43 am

      Thanks for sharing! Don’t forget to remove the carburetor bowl and drain out any remnants of fuel once the engine runs out of gas.

      Reply to this Comment

  10. Dan
    on August 13, 2013 at 5:05 pm

    Recently got a gocart that hadn’t been run in I don’t know how long. Engine had great compression etc so I filled with gas but it wouldn’t run. Pulled the fuel bowl and found the aluminum was all pitted and all the ports were plugged. But even worse the bowl looked like it was full of a white paste similar to toothpaste.

    Reply to this Comment

  11. kenny stevens
    on August 13, 2013 at 6:36 pm

    Just had to change carb on miller wildcat wouldn’t run took carb a part and it was nothing but white corrosion,white chalky.I put shut off valve on the fuel line.Now every time get finished using it I turn the fuel off and let it run till it burns up the fuel.

    Reply to this Comment

  12. gene sims
    on August 13, 2013 at 7:05 pm

    I work on Honda and Briggs and Stranton engines almost everyday,I’ve seen the damage ethanol is doing to the small engines,I recommend higher octane gasoline with fuel stabilizer and be sure to drain out the gasoline at the end of your summer season.

    Reply to this Comment

    • Turner Anderson
      on August 14, 2013 at 10:16 am

      Great advice Gene. We always recommend to our customers to add a fuel stabilizer to fresh gas. And especially drain all gas from your equipment before storage. Thanks for sharing!

      Reply to this Comment

  13. colin mcintyre ( mowers )
    on August 13, 2013 at 10:11 pm

    hi all
    boy I am glad we are not the only country having this problem here in Australia
    I get this all the time with the farmers you can tell them till you are blue in the face they don’t listen when you tell them they need a new carbie they scream blue murder & when you tell them how much that put’s the icing on the cake
    had one farmer here told me how to solve the problem ( avgas) plane fuel or ethanol shield made in U/S
    hope this helps reg/Colin

    Reply to this Comment

    • Turner Anderson
      on August 14, 2013 at 10:22 am

      Yes, some people actually need to physically see the effects, in order to believe it themselves. Ethanol Shield and Startron are popular stabilizers to use. Thanks for sharing Colin!

      Reply to this Comment

  14. Turner Anderson
    on August 14, 2013 at 9:58 am

    Great to hear Walter! Thanks for sharing.

    Reply to this Comment

  15. Turner Anderson
    on August 14, 2013 at 10:13 am

    Glad you liked the article. Thanks for sharing Bob.

    Reply to this Comment

  16. Turner Anderson
    on August 14, 2013 at 10:26 am

    Maybe the third time’s the charm. You might be seeing his trimmer or chainsaw next. Thanks for sharing Casey.

    Reply to this Comment

  17. Rich
    on August 14, 2013 at 1:52 pm

    The effects of ethanol are widely known and are only going to get worse with E-15 . Phase seperation and water absobrbtion are bad enough with E-10 , add 5% more ethanol and you will add more problems . For those of you who dont know , many marinas sell medium grade (89 Octane) ethanol free gasoline for boats , its more expensive than regular pump gas , but I feel its worth it .

    Reply to this Comment

  18. glen fuller
    on August 16, 2013 at 5:55 pm

    Thanks for a fine article. We have a 100 acre farm and so I have over 30 engines to care for, both 2 and 4 cycle and diesel. In over 40 years of working on small engines I have never seen the amount of damage that E10 causes. I have seen brass floats with pinholes, damaged carburetors beyond saving, clogged jets and filters. You name it and that stuff will attack it. You dont use some tractors every day and consequently when you do, sure enough, you find a plug of water in the bottom of the tank. You can see it in the sediment bowl. A tip is to keep the tank full to minimize condensation from a hot day into cool night. The next best necessary thing to do is to add stabalizer to fresh fuel. The very best thing to do is find a station that sells non ethanol gasoline. Sure it costs more per gallon, a lot more, but it doesnt take much to spend the difference in repair parts and time.
    Here is a good example. A friend called and told me his chain saw had packed up. It is a large saw and quite expensive. He had it fixed once, ran two tanks through it and it packed up again. This time the repair facility required that he have the fuel analyzed. He did and here are the results. The pump read E10 (Here in NY State). The actual content of ethanol in the fuel was over 17%! My point here is that even though you think you are buying E10 what you are getting may be something way over that. We, as consumers, are too trusting of these fuel companies to actually give us the product they claim. Switch to ethanol free. Your engines will run trouble free and last a long time, just like they used to.

    Reply to this Comment

  19. Richard Key
    on August 16, 2013 at 9:01 pm

    Just repaired a generator carb today. Ethanol was the culprit. I tell all my customers not to use it or put some kind of stabilizer in it. Very good article. Wish all my customers could see it.

    Reply to this Comment

  20. maxoverload
    on August 18, 2013 at 3:50 pm

    warren , be happy you are a tech , or mechanically oriented , the thousands of mom & pops , or mow and go equipment owners are not as fortunate .

    Reply to this Comment

  21. The Limb Reaper (Brant)
    on August 22, 2013 at 6:16 pm

    I just replace a carburetor on a Yard-man (MTD)mower which was a “trash-day” find. Someone had ruined a 2 year old push mower with Ethanol gas. My girlfriend was quick to tell me to “pick it up fast before it’s gone”. I ordered a new carb. on Sunday evening from you folks and had it waiting for me on Wednesday. Nice web site and great service. Thanks!

    Reply to this Comment

  22. Robert
    on November 24, 2013 at 10:10 pm

    I cannot count how many carbs I have rebuilt because of this horrible fuel. But I noticed something: None were 2-strokes. My thinking is the oil in the gas is the difference.

    So, I started running all my equipment, 4-strokes included, on pre-mix fuel. Yes I know a lot of people are gonna say it carbons up the valves, combustion chamber, etc. but so far in 3 years of running pre-mix in everything I have had no problems.

    Reply to this Comment

  23. Dan aka da Chowdahed
    on January 13, 2014 at 7:39 pm

    100% agree with Warren about the use of sta-bil. I also use 92 octane gas and airtight tanks. Installed fuel shutoffs in everything. If I know I’m not going to use machine within a few days, when done using I shut the fuel off and let it run until it stops by itself. Getting fuel shutoffs for each piece was time consuming and depending how you look at doing it, it was a little bit of a pain in the a*s, but have not had any start up problems ever since I put them in, about 5 years now.
    One point I would like to add to the very informative video and other posts is also to replace the fuel lines with the best fuel line you can get. If your fuel lines are more than 5-6 years old, they may very well be getting nasty inside, gummy and soft junk which really is not a great thing trying to get thru the carb. Problem with a push lawn mower with a small Tecumseh. It started to run rough and stall. Dropped bowl on carb saw some nasty crud. Looked closer at fuel line and it was all gooey inside. Cleaned carb, replaced fuel line with fuel injector line, found a fuel shut off that would work, not problem since.
    I said in the beginning of my post that I use 92 octane with Sta-bil. I’ve been told that it is not great for the valves but also been told it is not a problem. But, when it is cold, it seems like that extra octane makes it easier & quicker starting. I compression test all my engines spring and fall,check/adjust valves, sounds like overkill, but I have the equipment and some extra time, and have found no problems with valves by using the 92 octane fuel.
    Good luck to all with dealing with this Ethanol.

    Reply to this Comment

  24. Steve La Duke
    on April 5, 2014 at 11:43 am

    I found very early what ethanol in your gas can do to your small engines and have for the past 20 years buying super unleaded, high octane gas without any ethanol added. And here’s the problem I see with this scenario.
    Most gas stations offer 3 grades of gas with only one pump hose despencer. So you fill your 5 gallon gas tank with the one hose available. And who do you thing used this pump last. Of course, the guy before you filled his tank with low lead ethanol gas. And how much gas is left in that hose do you suppose? Well, I figure around at least 1/4 gallon of ethanol adultratetd gas goes into you plastic tank before your can even starts getting the super unleaded gas that you want because that hose has to empty before it begins to pump out of the super unleaded supply tank. Right? Think about it.
    Anyway, what I do now is drive up to a gas pump that has no ethanol gas in one of the offerings on the pump, push the super, high octane button on the pump and then put one gallon into my auto’s tank before I fill up my gas can. That is the only way to eliminate that ethanol that is in the line already.
    So how many people in this country fill up their gas cans every day and pour at least a 1/4 gallon of udulterated gas into their cans when they are paying for a higher premium gas that cost almost .50 cents more a gallon than that crappy ethanol gas?
    Most gas stations don’t have a seperate hose for all three of the different grades of gas that they offer, and this is the only way to eliminate the ethanol in the gas they purchase at the station when pumping from a single hose pump.
    And after I finish filling my gas tanks with the non ethanol gas, I shut off the pump, then restart the pump and empty the high test gas still left inside the hose into my auto with an extra gallon of gas. Why should I let some other guy get my .50 cent per gallon more expensive gas that I paid for?
    S. La Duke

    Reply to this Comment

  25. Joe
    on January 3, 2015 at 10:35 pm

    What I did was put Silicone Grease on all my seals to refurbish a carburetor that was previously leaking on my Tecumseh Snow Blower engine since the E10 Fuel had shrunk the rubber seals and dried them out a little. This seemed to keep it from leaking anymore but do not know how long it will last. I went by the local Small Engine Shop today to get a rebuild kit but it does not contain the O-Rings on the Pickup Tube that injects the fuel into this carburetor the O-Rings were shrunken and the tube fell right out. I rubbed the Silicone Grease on the O-Rings and reinserted it back into the Carburetor. Ran like a charm afterwards.

    Seems this is major problem 1 person came into the shop to pickup a new Carburetor and the other 2 were there to pickup their Snow Blowers with Carb Repairs.

    Reply to this Comment

    • Jeff T.
      on February 2, 2016 at 7:06 am

      The O-Rings on the Pickup Tube can be found in almost any hardware store. Look in the O Ring box and they should be the smallest ones. I have replace thousands of them.

      Reply to this Comment

    • Gary Collins
      on September 28, 2016 at 6:51 pm

      Silicone grease is glass you will find warnings on all auto manufacturers not to use it anywhere in any fuel flow device. It damages valves and catalytic converters by forming glass on those devices. If you have used it in a fuel flow situation in any device that has a catalytic converter it is already damaged. I think valves take more to damage but catalytic converters are damaged at first burn because they get coated with fine glass particles in the hot exhaust flame. Don’t use Silicone of any kind in a fuel flow area.

      Reply to this Comment

  26. Jerry
    on January 27, 2015 at 6:14 pm

    What is the effect if you have a pitted float bowl but the rest of the carb is spotless?

    Reply to this Comment

  27. Bob Koch
    on March 10, 2015 at 6:44 pm

    Years ago we used to purchase a product nicknamed day gas for use if you had water in the tank. Could that be used to absorb the water that the alcohol attracts?

    Reply to this Comment

    • Mark Wallner
      on May 12, 2015 at 11:51 pm

      Bob Koch said “Years ago we used to purchase a product nicknamed day gas for use if you had water in the tank. ”

      It was actually called “Dry Gas”, and was used a lot up in New England. As I was told, it was supposed to mix with the water AND the gas, thereby dispersing the water throughout the gas and preventing fuel-line freezups.
      I once put some gasoline in a jar, added a little water, and added some Dry Gas to see what would happen. Even if I shook it up, and no matter how much Dry Gas I added, I ended up with a thick blob of wet Dry Gas rolling around in the bottom of the jar of gasoline.
      I’m guessing it was alcohol, and it might have mixed with the water in high enough concentrations to prevent freezing, and maybe even to burn in the engine, but it didn’t look good in the bottom of that jar. I stopped using it.

      Reply to this Comment

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  29. Miler
    on July 2, 2015 at 5:31 am

    Im no expert but i believe those engines require a gas/oil mixture for lubrication, and burning pure ethanol might cause them to overheat

    Reply to this Comment

  30. Gary
    on July 16, 2015 at 3:25 pm

    I use Sea Foam in all my gasoline products. Truck, lawnmower, edger, weed trimmer, blower, etc.

    Reply to this Comment

  31. Dave Lindsay
    on July 17, 2016 at 6:20 am

    Germany tried ethanol and they STOPPED because it was causing problems.

    Ethanol is For DRINKING, not for my 1985 Alfa Spider !

    Reply to this Comment

  32. Chuck
    on August 14, 2018 at 6:41 pm

    New Holley 4 barrel, sat on engine for over 18 months. Carb. Ruined . Ate gasket and metering block and jets pitted.
    Out $625.00 for new carb.

    Reply to this Comment

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