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Small Engine Care and Storage Tips

small engine carburetor

Gum and varnish build-up inside a small engine carburetor will eventually lead to problems. Copyright 2018 Tim Carter

"Gasoline begins to degrade about thirty days after it's pumped."

Small Engine Care and Storage TIPS

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DEAR TIM: Spring has finally arrived in the high country here. It's time to cut the grass, but the small gasoline engine on my lawn mower refuses to start. I use the same gasoline that goes in my truck, and my truck always starts.

My guess is that you work with small engines all the time and know what the problem might be and how to prevent it.

What's the best way to store a small engine for months so when it's time to use it you can depend on it starting? Don G., Baker, NV


DEAR DON: I used to have hard-start issues with small engines. I've also had small engines that refused to start no matter how much starting fluid you squirt in the air filter.

How Can I Start Engine First Pull?

You can have your small engine start first pull if you do the following:

  • store the engine with a full tank of gas
  • use 91 octane or higher gas with stabilizer
  • start the engine every 30-45 days to keep fuel in the carburetor

Years ago I discovered a trick that ensures my small engines start the first pull each time I take them out of winter or summer storage.

CLICK HERE to get FREE & FAST BIDS from local handymen that can clean your small engine carburetor.

Your truck starts all the time because you drive it frequently and the gasoline in the tank and fuel system are almost always fresh. If you add gasoline to your truck every thirty days, you'll rarely have problems.

People that don't drive their cars much should absolutely continue reading because they need to do what I do with my small engines.

Did You Talk With a Briggs & Stratton Engineer?

I decided that I'd blend my years of personal experience with the vast knowledge base of Briggs & Stratton's Wayne Rassel, an engineer, to shed some light on how to store small engines. I have small engines in snow blowers, a lawn mower, a hydraulic log splitter and a standby generator. All the engines sit idle for months at a time, so it's important that they respond when I need them.

What are the Best Storage Practices?

I discovered a simple trick years ago that allows my engines to start each time I pull the starting cord. But information I got from Wayne has caused me to modify my approach to storing small gasoline engines.

Now I incorporate the best practices known to woman or man about how to ensure small engines start.

Is Ethanol BAD for Small Engines?

Yes, ethanol is very bad for small engines and even larger ones like in your car or light truck.

The gasoline you and I purchase contains 10-percent ethanol. Using gasoline that contains more than 10-percent ethanol can cause significant damage to small engines, so avoid it at all costs.

If you want to put the best gas in your small engines, get ethanol-free gasoline.

Where Can You Find the Best Gasoline?

There is a website called pure-gas.org that has a list of over 10,000 locations, broken down by states or provinces, that sell pure, ethanol-free gas.

If you can't locate a station near you, just visit your local small airport. All aviation gasoline is ethanol-free. You can buy great gasoline at any small airport.

Some boat marinas may also sell ethanol-free gasoline.

CLICK HERE to get FREE & FAST BIDS from local handymen that can clean your small engine carburetor.

Does Gasoline Break Down?

Gasoline begins to degrade about thirty days after it's pumped. If you've not used all the gasoline in your gas cans within that time frame, pour it into your truck's fuel tank and drive to the gas station to get fresh fuel for your small engines.

That's what I do. I never put gasoline in my small engines that's older than thirty days.

What is the Chemistry of Gasoline?

Understand that ethanol-based fuels tend to attract water. Water is heavier than gasoline.

IMPORTANT TIP: If you don't operate your engines on a frequent basis, a layer of ethanol-enriched water can settle to the bottom of the tank and be drawn up into the carburetor and engine.

This water-ethanol blend is highly corrosive to small engine parts.

How Does Gum & Crap Form?

Gum and varnish, chemical compounds in the gasoline, form as the fuel degrades. This gum and varnish can lead to stuck intake valves, clogged fuel lines and jets in the carburetor.

This could be why your engine is refusing to start. It could be clogged with this gunk.

Should the Tank Be Filled at All Times?

I keep my small engines in great shape by keeping the gas tank filled to the brim at all times. I do this after I shut the engine off.

I do this even if I'm going to use the engine in a week. Keeping the tank filled with fuel minimizes the oxygen in the tank.

Oxygen reacts with gasoline causing degradation. 

Storage Tip

At the end of each season, I discovered that if I ran the engine completely out of gas right before storing it for months, I'd be able to restart the engine with no issues. However, after talking with Wayne, I've decided that state-of-the-art fuel treatments and stabilizers are probably the best way to protect my small engines throughout the entire year.

What About Modern Stabilizers?

Some modern fuel additives have a triple anti-oxidant formulation that slows down the fuel degradation issue. The chemicals in the additives react with the gasoline preventing outside water vapor from causing the gasoline to deteriorate.

gas stabilizer

This is the gas stabilizer I use. It's not expensive and it works. CLICK THE IMAGE NOW TO ORDER IT.

The additives protect the entire fuel system and all engine parts exposed to the gasoline. Metal parts receive a protective coating that prevent rust and corrosion.

Metal deactivators in the additives stop aggressive chemical reactions caused by dissolved metal ions in the fuel. Detergents in the additives help prevent the formation of the gum and varnishes that cause hard or no-starting issues.

You can get long-lasting results if you decide to use the advanced formula fuel stabilizers. If you want two years of protection, just add one-half ounce to each 2.5 gallons of gasoline. Double the amount of stabilizer and you can protect gasoline up to three years.

Since I take a conservative approach to small engine care and maintenance, I'm going to start to add the fuel stabilizer to all my gasoline. I want to protect the metal parts in my engine. The fuel stabilizers are not expensive, and one 8-ounce bottle treats up to 40 gallons of gasoline. Believe me, I can blow lots of snow and cut lots of grass with 40 gallons of gasoline!

CLICK HERE to get FREE & FAST BIDS from local handymen that can clean your small engine carburetor.

Column 992


43 Responses to Small Engine Care and Storage Tips

  1. Tim-
    I have had the same problems as Don and while your advice is good, a more immediate solution that I have used is to: empty the tank; empty, clean and /or replace the fuel filter; add an additive called "Start" from Sta-Bil to new gasoline per instructions, then fill it up and start it up. Always started right up,first or second pull. Good Luck!

  2. Tim-
    2 more things:
    The actual name for this is " Start Your Engines!" And always replace the spark plug for the new season.

  3. Hey Tim, I used to own a Kawasaki dealership and we made really good money on people not prepping their small engines. We always added stabil to the fuel and let the machine run to get it into the carb. We also always topp off the fuel tank so no moisture can get in there. If you have a metal tank they can rust over one season. If we had a two stroke motor we removed the spark plugs and fogged the cylinders then put the plugs back in. Just google engine foggers. Also you can spray the engine with the fogger as well this will keep condensation off the metal parts in a hot/cold garage area. This always works. Hope it helps.

  4. I constantly had these same problems with my push mower, weed eater and chain saw. I now use Marine Grade Stabil. I put it in my 5 gallon container every time I get fuel and I have not had a problem since.

  5. So I am assuming that you don't have to be concerned about the 30 day time frame after the gas is pumped because you are using the fuel stabilizers?

  6. At the last mowing of the season I start my lawn tractor run my it until the tank is bone dry. This spring I added gasoline to start my first mowing and it started on a dime. I only add enough gasoline for one mowing at a time. I am a 76 year old lady and a friend told me about old gas becoming shellac if not used within 30 days.

  7. Tim,
    My small engine repair shop told me the same thing that your recent column did. He recommended the Sta-Bil with "ethanol treatment." I have stopped cursing my string trimmer manufacturer. My BMW dealer recommended that I pore a BMW product periodically in the gas tank to deal with the ethanol issue to forestall any potential power problems.

  8. Hi Tim,
    Good article about fuel stabilizers - been using them for years. But two things I never could understand... I just have one small lawn mower and use the gas out of a 1 gallon container, so it's a pain figuring out those formulas for just 1 gallon. OH..... and unless things have changed, the fuel stabilizer itself will go bad on you after about a couple of seasons 🙂 More wasted of money..... earlier I tossed out about 4 ounces.... Yes, hard at times finding those smaller bottles


    • i dont throw out my old gas. i put in my car. it will not hurt the cars engine. it has a 15 gal. tank and to add 1/2 gallon of 6 month of gas is not going to damage the rest of the gas in the tank.


    • Some people swear by Stabil, but, my small engine shop swears by Seafoam. At their suggestion, I have used it in all of my equipment for engines that use straight gas and for the ones that use a gas/oil mix. I have not had a starting problem since I started using it. It runs about $8 to $9 per container and that treats a lot of fuel.

  9. I too have had problems with gas - usually in 2-stroke engines. I took the advice of our local Fire Chief who was in charge of equipment with small engines (fans, generators, chain saws, etc). that are used infrequently. USE ONLY NON-OXYGENATED FUEL, It costs a little more but can be stored in engines for months at a time.

  10. The local consumer guy says go to wwwpuregas.com. It has a locator to find stations that sell no ethanol gas. Luckily there was one right down the road. It may be $4/ gal, but I feel better already

  11. Yes, Roger's is my question, too.

    How do we know which fuel stabilizers have advanced formulae?
    What brands/models of stabilizers work well?


  12. Tim. I have gas in my generator since hurricane Sandy. Should I dump it out, run it until its empty or add stabilizer? Also should you add stabilizer then run the engine so the fuel goes throughout the system ? Thank You Frank Russo Staten Island N.Y.

  13. I've used stabilizers for a long time. Sometimes you forget,etc. There is a great product called Seafoam that you can add to the gas to get it started. My snowblower stubbornly wouldn't start just added a little to the gas tank, several pulls it starter. Also sold in spray for directly into carburetor. Put 2 oz in gas can.

  14. I have used sta-bil for years now, I use to run dry my engines the problem was next season the gumming of the carb would freeze the float in place. The sta-bil works fine but if you using in a engine like a snow blower run the engine each year. we had a few years with no snow and when I started it there was a concentration of sta-bil in the carb and it started but the black smoke was intense and left a oily residue were ever it hit.

  15. I take the spark plug out and spray some WD-40 in to help lub and make the start easier. I also change the oil at the start of each season.

  16. For decades I have maintained 15 gallons of gasoline for small engines (mower, snow blower, chain saw, generator) by using Stabil in each 5 gallon can. The 15 gallons were chosen to be sure I could keep my generator running for several days. Every 6 months I pour whatever is left in the cans into my car tank and then refill the 3 cans (leftover gas mixed with oil also goes in the car tank without any harm to the car). I keep each engine gas tank full to decrease space where condensation can occur and foul the gas. Each engine starts on the first attempt. I also have had no problems with using sparkplugs for two years before replacement.

  17. I had a mower that would not start in cold weather. First I used a propane torch --not lit--and placed the tip into the throat of the carburetor. Though awkward it worked. Next I tried placing the tip into the gas tank and let the propane bubble through the gas. The mower fired up first pull. I suspect some of the propane "dissolves" in the gasoline and is released in the carburetor.

  18. Tim - I read with interest your notes about fuel stabilizers & just wanted to say that I have had numerous small engines for over 40 years have never used any type of fuel stabilizer & never given the engines any special treatment when putting them away for long periods. I have never had any problem starting any of them - trimmer, mower, chain saw, lawn tractor or snow blower.

    • Brian,

      You're a lucky man. It's the ethanol in gas that's causing the issues. I'm about to write another very authoritative column about what's REALLY happening.

      It would be very prudent of you to use the BEST stabilizer you can find. These products are very inexpensive and worth every penny.

  19. All sorts of good advice here but once the damage is done then what? I have a Honda-powered pressure washer that I emptied the tank on due to problems starting. I only need this thing to run about once every 3 years and no matter how carefully I prep it for long term storage it always ends up in the shop.
    My V8 flathead Ford truck gets used about as often and starts on the gas that's been in the tank since the last time I used it.

  20. Inexpensive mower with a Briggs & Stratton engine. I've had if for 20 years and I've never followed any of your recommendations. Always starts on the second pull, except the first start of the year which takes one additional pull. Gas that sits in the can all winter (4.5 months) seems to work just fine. Guess I'm just lucky.

    • Wonder if you would have that same experience with one of the small engines made in the past 5 years with more severe carburetor adjustments due to current environmental regulations and ethanol gasoline.

  21. No mention is made how long to "bubble the propane" in the gas tank.

    I have not had problems with a 1985 Toro lawn mower. I replace the (air) filter and oil once every year or two. Spark plug every 2-3 years. The body (cast aluminum) is developing holes however. I run it dry at the end of the season; have used gas from fall left over into spring, no issues. It is probably due to Toro's great reputation back then.

    My brother owns a late model Toro that you have to "prime" with a push bulb and that thing is a royal PITA!

    If anyone is only going to use a pressure washer once every few years, it would be better to rent the unit from a rental center, you're guaranteed to have a unit that works. Don't spend the money on buying. Besides it's a space waster in your garage.

    Just sayin'...

  22. It depends on which appliance it is on. For infrequent usage items like generators and pressure washers, I run them dry then dismantle the carb clean & dry out the bowl, coat with mystery oil, take off the sparkplug and put motor oil pulling the rope then buttoning up ready to refill gas at next use. for seasonal items like lawn mowers and snow blowers I do the gas stabilizer.

  23. I've been using Star Tron with great results. It was recommended by my small engine mechanic as being superior to Sta-Bil, but does cost more.

  24. I also have been using Star Tron for almost four years now and am very pleased with it. I try to buy it in the 32 oz. bottle and the cost comes out very inexpensive per gallon of fuel. I put it in all my gas cans before I go to get them filled, about 17 gal. at a time and use it in everything, 1960 Ford tractor, Gravely zero turn mower, push mowers, weed eaters, chain saws, etc. Very happy with it.

    • Still using Star Tron, been 7 years now and still no problems. Before I started using it I was constantly having starting problems, 2 cycle gas lines would just kind of desolve in the tank. My NAPA dealer recomended it to me and he was right, it works.

  25. In small engines why not find non alcohol gas and use it? Only a couple of states don't have it. Has any one used this in non alcohol gas?

  26. No mention of aviation fuel. At end of season, I run my small engines on AVF prior to storage for winter. This eliminates gas related issues for me.

  27. This article and responses are priceless. It should be repeated every year as it is ageless information. So many responses from those that make their living off small engines and have first hand knowledge. Decades of knowledge in one article. A winner.
    I'm 76 and it took me a lifetime to figure out things mentioned for small engine success.

  28. I used the product you recommend and kept the gas in the lower over the winter. I had to clean the carb in order to get it to start.

  29. For my snowblower and chainsaw that gets very infrequent use I use either trufuel, or aspen synthetic fuels. They keep for up to two years, and are prestabilized. No fussing around. Starts up all the time.

    Also, keep fuel tanks full all the time to prevent condensation.

    Gas station fuel is ALWAYS stabilized and even so I rotate it in 30 days if I haven’t used it. No exceptions.

    I don’t trust gas station fuel for more than 30 days.

    Canned fuel ive left for over a year and no issues on start up. None.

    If you find canned fuel too expensive (cheaper than carb fixing unless diy) than here is your compromise:

    Utilize stabilized fuel all season (rotated at 30 days)

    At the end of the season I.e drain all the stabilized fuel from your mower, and fill up with canned fuel, let it run for 10 minutes, top up the tank with canned fuel and anxiously await for that start on the first pull. I guarantee it will happen.

  30. One thing nobody has mentioned. Gasoline is seasonally formulated. The difference is primarily butane content. More in winter so it evaporates quicker for easier starting, less in summer so it doesn't evaporate too much, which causes vapor lock. You shouldn't have any problem starting a lawnmower on leftover winter gas, but starting a snowblower on summer gas can be difficult. I always try to wait until the end of November to refill the gas can for the snowblower. Occasionally it snows before that, but it's not cold enough yet to make starting on summer gas impossible.

  31. I agree with your suggestions, Tim. The other tips are good as well. I own a Toro lawnmower that was new when Ronald Reagan was in the White House. It continues to run to this day. I have a Homelite weed whacker that's 22 or so years old. It, too, continues to run each year.

    The tip I have not seen noted here and which I have had success with doing on these as well as other small-engine devices would be to remove and inspect the spark plug. Clean it if it looks OK. Furthermore, I clean the combustion chamber using an awl or a small screwdriver to scrape away the black soot that usually coats the chamber. Don't scratch the chamber, just scrape it enough to remove the black deposits inside.

  32. Ethanol also does great harm to antique automobiles. It can eat all sorts of seals. If the gas has not been treated, as discussed above, it turns much of the gasoline in the tank into gunk, which next time you run the engine will clog the gas line, filters, vacumn tanks and gas pumps, and the tank itself.

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