Leaving old gas in your lawn mower might seem like a minor oversight, but it can lead to a cascade of problems that impact your mower’s performance and lifespan. From gummed-up carburetors to corroded fuel lines, the consequences of neglecting this aspect of lawn mower maintenance are often more significant than you might expect. This article will delve into the various issues that arise from using old fuel in your lawn mower and provide guidance on preventing them.
The Chemistry of Old Gas: Why It Goes Bad
Gasoline isn’t a stable compound; it’s a blend of various hydrocarbons that are susceptible to degradation over time. The aging process is accelerated by exposure to air, moisture, and temperature fluctuations.
Evaporation and Volatile Compounds
One of the primary issues with old gas is the evaporation of its more volatile components. These light hydrocarbons are essential for easy starting and smooth engine operation. As they evaporate, the remaining fuel becomes heavier and less combustible, making it harder to ignite in the engine. This can lead to starting problems, rough idling, and reduced power.
Oxidation and Gum Formation
Another significant factor is oxidation. When gasoline is exposed to oxygen, it undergoes a chemical reaction that results in the formation of gummy residues and varnish. These sticky substances can clog fuel lines, jets in the carburetor, and other critical engine components. Gum formation is a common culprit behind lawn mower engine problems, especially after periods of storage.
Water Absorption and Phase Separation
Gasoline can also absorb moisture from the air. This is especially problematic with ethanol-blended fuels, as ethanol readily attracts water. When gasoline absorbs enough water, it can lead to phase separation, where the ethanol and water separate from the gasoline and settle at the bottom of the fuel tank. This water-ethanol mixture is highly corrosive and can damage the fuel system. Engines cannot effectively burn this mixture, causing significant performance issues.
Impact on Lawn Mower Components
Leaving old gas in your lawn mower can affect various parts of the engine and fuel system. Let’s look at the components most susceptible to damage.
Carburetor Problems
The carburetor is responsible for mixing air and fuel in the correct ratio for combustion. The narrow passages and small jets within the carburetor are easily clogged by gum and varnish from old gasoline. A clogged carburetor can cause starting problems, poor idling, and reduced engine power. In severe cases, the carburetor may need to be professionally cleaned or even replaced.
Fuel Line Deterioration
Fuel lines are responsible for transporting fuel from the tank to the carburetor. Old gasoline can cause fuel lines to become brittle, cracked, and leaky. Leaks not only waste fuel but also pose a fire hazard. Replacing deteriorated fuel lines is essential for safe and efficient operation.
Fuel Tank Corrosion
The inside of the fuel tank can also suffer from the effects of old gas. Corrosion can occur, especially if water has accumulated in the tank. Rust particles can then clog fuel filters and carburetors, further exacerbating engine problems.
Engine Damage
While less common, persistent use of old gas can eventually lead to more significant engine damage. Poor combustion can result in carbon buildup on the pistons and valves, reducing engine efficiency and potentially causing valve damage.
Symptoms of Using Old Gas
Recognizing the symptoms of using old gas is crucial for addressing the problem before it leads to more serious issues. Here are some common signs to watch out for:
- Difficulty Starting: This is often the first sign that old gas is causing problems. The engine may crank but fail to start, or it may take multiple attempts to get it running.
- Rough Idling: If the engine idles unevenly or stalls frequently, it could be due to a clogged carburetor caused by old gas.
- Reduced Power: The engine may lack its usual power and struggle to cut through thick grass.
- Stalling: The engine may stall unexpectedly, especially when under load.
- Unusual Noises: Strange noises, such as popping or knocking, can indicate engine problems related to old fuel.
- Black Smoke: Excessive black smoke from the exhaust can be a sign of incomplete combustion due to stale fuel.
Preventing Problems Caused by Old Gas
Fortunately, preventing problems caused by old gas is relatively simple and inexpensive. Here are some strategies to implement:
Use Fresh Fuel
Always use fresh gasoline in your lawn mower. Ideally, purchase fuel in small quantities that you can use within 30 days. Avoid storing gasoline for extended periods, especially during the off-season.
Use a Fuel Stabilizer
Fuel stabilizers can help prevent the degradation of gasoline during storage. Add a fuel stabilizer to the gas can or directly to the fuel tank before storing your lawn mower for an extended period. Fuel stabilizers can extend the life of gasoline by several months. Always follow the manufacturer’s instructions for the correct dosage.
Drain the Fuel Tank
If you know you won’t be using your lawn mower for several months, drain the fuel tank completely. Run the engine until it stalls to ensure that the carburetor is also empty. This prevents gum and varnish from forming in the fuel system.
Proper Storage
Store gasoline in a clean, airtight container in a cool, dry place. Avoid storing gasoline in direct sunlight or near sources of heat. Proper storage can help slow down the degradation process.
Regular Maintenance
Regular maintenance, including changing the air filter, spark plug, and oil, can help keep your lawn mower running smoothly and efficiently. A well-maintained engine is less likely to be affected by the minor issues caused by old gas.
What to Do If You Suspect Old Gas Is the Problem
If you suspect that old gas is causing problems with your lawn mower, here’s what you should do:
- Drain the Old Fuel: Drain the fuel tank completely and dispose of the old fuel properly. Never pour old gasoline down the drain or into the ground. Contact your local waste management authority for information on how to dispose of gasoline safely.
- Clean the Fuel System: Clean the fuel tank, fuel lines, and carburetor to remove any gum or varnish. You can use a carburetor cleaner spray or a specialized fuel system cleaner.
- Replace the Fuel Filter: The fuel filter is designed to trap contaminants and prevent them from reaching the carburetor. Replace the fuel filter regularly to ensure a clean fuel supply.
- Use Fresh Fuel: Fill the fuel tank with fresh gasoline and add a fuel stabilizer.
- Start the Engine: Attempt to start the engine. If it still doesn’t start or runs poorly, you may need to have the carburetor professionally cleaned or rebuilt.
Long-Term Storage Considerations
Preparing your lawn mower for long-term storage requires extra attention to prevent fuel-related problems.
- Stabilize and Drain: Combine fuel stabilizer with the remaining gas in the tank and run the engine for a few minutes to circulate the treated fuel through the system. After that, drain the fuel. This coats the internal components with stabilized fuel and prevents corrosion.
- Fogging Oil: For added protection, consider using fogging oil. This is sprayed into the engine’s cylinder through the spark plug hole after draining the fuel. It coats the cylinder walls and prevents rust formation.
- Battery Care: If your lawn mower has an electric start, disconnect the battery and store it in a cool, dry place. Consider using a battery tender to keep the battery charged during storage.
The Role of Ethanol in Fuel Problems
Ethanol, an alcohol added to gasoline to increase octane and reduce emissions, presents unique challenges for small engines like those in lawn mowers. As mentioned earlier, ethanol attracts water, which can lead to phase separation and corrosion.
Understanding Ethanol Blends
Most gasoline sold today contains some percentage of ethanol, typically E10 (10% ethanol). While E10 is generally safe for most modern vehicles, it can cause problems in older engines and small engines that are not designed to handle ethanol.
The Impact of Ethanol on Small Engines
Ethanol can damage rubber and plastic components in the fuel system, leading to leaks and fuel delivery problems. It also promotes corrosion of metal parts. The water absorption issue is particularly problematic, as it can lead to phase separation and engine damage.
Using Ethanol-Free Fuel
If possible, use ethanol-free gasoline in your lawn mower. Ethanol-free fuel is less likely to cause corrosion and phase separation problems. It is often available at marinas and specialty fuel retailers.
Final Thoughts
Leaving old gas in your lawn mower can lead to a range of problems, from starting difficulties to engine damage. By understanding the chemistry of old gas and taking preventive measures, you can keep your lawn mower running smoothly and extend its lifespan. Always use fresh fuel, add a fuel stabilizer, and drain the fuel tank before long-term storage. Regular maintenance and attention to detail will ensure that your lawn mower is ready to tackle any lawn care task.
FAQ 1: How does old gas affect a lawn mower’s performance?
The primary issue with old gasoline in your lawn mower is its degradation over time. Gasoline begins to break down, forming gum and varnish deposits that can clog the fuel system. This includes the carburetor, fuel lines, and fuel filter. These deposits restrict fuel flow, leading to hard starting, rough idling, reduced power, and even complete engine failure.
Furthermore, ethanol-blended gasoline, commonly found at gas stations, attracts moisture. This moisture can separate from the gasoline, forming a corrosive layer that damages fuel system components and reduces the octane rating of the fuel. The lower octane rating can cause engine knocking and further degrade performance.
FAQ 2: What are the signs that my lawn mower has old gas in it?
Several indicators can suggest that your lawn mower is suffering from the effects of old gasoline. Difficulty starting the engine is a common sign, as the degraded fuel may not ignite easily. You might also notice the engine running rough, sputtering, or stalling frequently, especially under load.
Another telltale sign is a noticeable decrease in the lawn mower’s power. The engine might struggle to cut through thick grass, or you might experience a reduction in the overall cutting speed. Visually inspecting the fuel can sometimes reveal problems; old gasoline may appear darker, have a varnish-like smell, or contain visible sediment.
FAQ 3: How long does gasoline typically last in a lawn mower?
Gasoline’s shelf life in a lawn mower is generally shorter than many people realize. Unleaded gasoline without any stabilizers typically starts to degrade within 30 days, while gasoline with ethanol can degrade even faster due to its tendency to absorb moisture. After 3 to 6 months, the degradation becomes significant enough to cause noticeable performance issues.
The storage conditions also play a crucial role. Storing your lawn mower in a cool, dry place away from direct sunlight can help prolong the gas’s lifespan. However, it’s still recommended to use fuel stabilizers if the lawn mower will be stored for more than a month or two to prevent the formation of gum and varnish.
FAQ 4: Can using a fuel stabilizer prevent problems with old gas?
Yes, fuel stabilizers are designed to prevent the degradation of gasoline and protect your lawn mower’s fuel system. They work by inhibiting oxidation, preventing the formation of gum and varnish deposits, and helping to control moisture absorption, particularly in ethanol-blended fuels. Adding a fuel stabilizer to fresh gasoline before storing your lawn mower can significantly extend the fuel’s lifespan.
Using a fuel stabilizer is a proactive measure that can save you time and money in the long run by preventing costly repairs. It’s crucial to follow the manufacturer’s instructions for the correct dosage. Remember, fuel stabilizers are most effective when added to fresh gasoline; they can help prevent degradation but can’t fully restore already degraded fuel.
FAQ 5: What should I do if I suspect my lawn mower has old gas in it?
The first step is to drain the old gasoline from the fuel tank. Safely dispose of the old gas according to your local environmental regulations; do not simply pour it down the drain or onto the ground. Once the tank is empty, consider adding a small amount of fresh gasoline to the tank and sloshing it around to help loosen any deposits that may have formed.
Next, check and clean the fuel filter. If the filter is heavily clogged, replace it. You may also need to clean the carburetor to remove any gum and varnish deposits that are restricting fuel flow. In severe cases, you might need to disassemble the carburetor for a thorough cleaning, potentially soaking it in a carburetor cleaner. If you are not comfortable performing these tasks, it’s best to take your lawn mower to a qualified repair shop.
FAQ 6: Are there specific types of gasoline that are better for lawn mowers?
For lawn mowers, using gasoline with a lower ethanol content, or even ethanol-free gasoline if available, is generally recommended. Ethanol-blended gasoline can attract moisture, which can lead to corrosion and fuel system problems. If you must use gasoline with ethanol, ensure it is E10 (10% ethanol) or lower.
Another option is to use premium gasoline, which often has a higher octane rating and may contain additives that help keep the fuel system clean. Always use the octane rating recommended by your lawn mower’s manufacturer. Regardless of the gasoline type, using a fuel stabilizer is highly recommended, especially if you plan to store your lawn mower for an extended period.
FAQ 7: How can I properly store my lawn mower to prevent gas-related problems?
Proper storage is key to preventing fuel-related issues in your lawn mower. Before storing it for the off-season, drain the fuel tank completely or, alternatively, fill the tank with fresh gasoline treated with a fuel stabilizer. Running the engine for a few minutes after adding the stabilizer ensures that the treated fuel circulates through the entire fuel system.
Disconnect the spark plug wire to prevent accidental starting during storage. Store the lawn mower in a clean, dry place, preferably indoors, away from direct sunlight and extreme temperatures. Covering the lawn mower can also help protect it from dust and moisture. Following these steps will significantly reduce the likelihood of fuel-related problems when you’re ready to use your lawn mower again.