Small Engine Won’t Start?

Bad gas is the number-one reason, and here’s how to prevent it.

Len Groom | TECHNICAL PRODUCT MANAGER, POWERSPORTS

In northern Minnesota, where I live, the temperature occasionally breaks 80°F (27°C) in the summer. When it does, it’s time to fire up my Jet-Skis* and hit the lake. The last thing I want to do on a sunny summer day is mess around with equipment that refuses to start or run properly.

Bad gasoline is the number-one reason seasonal equipment starts hard or runs rough. Over time, gasoline changes, leaving behind gums, varnish and other solids that foul the fuel system and prevent gas from flowing into the combustion chamber. In severe cases, gasoline can change so dramatically that it no longer ignites.

Gasoline is predominantly a mixture of carbon and hydrogen atoms bonded together into energy-dense hydrocarbons. Like conventional base oils, it’s derived from crude oil via a distillation process that uses heat, pressure and other catalysts to create different fractions. Gasoline is comprised of hydrocarbons that are lighter than those found in, for example, diesel fuel or conventional base oils. Refiners add ethanol to the formulation, typically 10 percent, but as high as 85 percent.

Time, however, takes its toll on gasoline. Exposure to heat, humidity, atmospheric pressure, oxygen and other variables degrade fuel.

In addition to gums and varnish becoming more concentrated and less soluble as lighter hydrocarbons  evaporate, gas is continually oxidizing, which further contributes to varnish and other gunk. Gasoline oxidizes more quickly than motor oil and its negative effects are more immediately noticeable. That’s why it’s important to use high- quality gas and store it in approved containers where air infiltration is limited, like inside a ventilated garage or shed, and not in the back of your truck or under the deck.

Meanwhile, ethanol added to gasoline at the refinery can absorb water from the atmosphere, which can lead to phase separation, which occurs when ethanol and gas separate, much like oil and water. Ethanol that has absorbed enough moisture and has sat long enough can foul the fuel system and prevent the engine from starting.

Comparison of Sea Foam Motor Treatment and AMSOIL Gasoline Stabilizer in the modified NACE TM0172 test using synthetic sea water per ASTM D665 part B.

This all sounds dire, but it’s nothing treating your gasoline with AMSOIL Gasoline Stabilizer (AST) can’t solve. Gasoline Stabilizer keeps fuel fresh up to 12 months. AMSOIL Ouickshot® (AOS) stabilizes gasoline during short-term storage up to six months, in addition to providing potent cleaning benefits and protection against ethanol issues.

What does stabilizer do?

That explanation may suit some people, but this is Tech Talk, so let’s look at the chemistry behind gasoline stabilizers.

You’ve probably heard terms like “free radicals” and “antioxidants” in relation to your health. A free radical is an unpaired electron, and most are unstable and highly reactive. They can either donate an electron to, or accept an electron from, other molecules. This starts a chain reaction that can lead to oxidative stress and cell damage. Left unchecked, free radicals can lead to health problems, like cardiovascular disease and cancer. To help fight free radicals, we should eat plenty of foods rich in antioxidants, which lessen their effects. Antioxidants can “donate” an electron to free radicals or trap them, effectively reducing their instability without becoming unstable themselves. Antioxidants aren’t silver bullets, but they go a long way toward improving our health.

By analogy, gasoline stabilizer is an antioxidant for your gasoline. It disrupts the free-radical-induced chain reaction that causes gas to oxidize and form varnish and gums. Some stabilizer products, like Quickshot, also contain chemistry that increases solvency and breaks down existing varnish, helping clean a dirty carburetor and restore performance. As shown, Gasoline Stabilizer also fights corrosion better than Sea Foam* Motor Treatment.

Neglecting to stabilize your gas can lead to all sorts of headaches when it’s time to remove your lawn mower, generator, string trimmer or Jet-Ski from storage. For best results, stabilize your gasoline all year long. That’ll ensure your equipment is ready to roll when you are.

Article is from the October 2019 Issue of the AMSOIL Dealer Magazine

*All trademarked names and images are the property of their respective owners and may be registered marks in some countries. No affiliation or endorsement claim, express or implied, is made by their use. All products advertised here are developed by AMSOIL for the use in the applications shown.

SLS Note: For years I followed the recommendations of the time by draining all the fuel from small engines and running the carburetors dry before storing for extended periods. What I found was upon refilling the fuel tanks, I had significant leaking at gaskets in the fuel system. To prevent the leaking from dried out gaskets, I tried leaving fuel in the system. What I got was gummed up carburetors that needed to be disassembled and cleaned before they would work the next season. Keep in mind that this was before the use of methanol in the fuel. About 20 years ago I started using AMSOIL Gasoline Stabilizer (AST) (and AMSOIL Quick Shot (AQS) when it was introduced) when I fill the gasoline containers I use for my various small engines. Since using the AST I have never had a problem starting any small engine after extended storage. The other thing that is important is to always fill the fuel tank after using the equipment. As mentioned above, oxidation is the enemy of fuel. By keeping the tank full of fuel when not in use, you reduce the amount of air space above the fuel which reduces the amount of oxygen available to react with the fuel. It also reduces the amount of moisture that can cause problems, especially with fuel with methanol.

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