Your lawn mower, your faithful companion in the battle against unruly grass, sputters, coughs, and refuses to start. More often than not, the culprit is bad gas. Gasoline, especially when left sitting for extended periods, degrades, leading to a multitude of problems. This comprehensive guide will walk you through the steps to diagnose and treat a lawn mower suffering from the effects of stale fuel, ensuring your mower roars back to life and your lawn looks pristine.
Understanding the Problem: Why Does Gas Go Bad?
Gasoline isn’t just gasoline. It’s a complex cocktail of hydrocarbons, designed to burn efficiently in an internal combustion engine. However, several factors contribute to its degradation over time.
Evaporation: Lighter, more volatile components of gasoline evaporate, leaving behind heavier, less flammable residues. This changes the fuel’s octane rating and its ability to ignite properly.
Oxidation: Gasoline reacts with oxygen in the air, forming gums and varnishes. These sticky substances can clog fuel lines, carburetors, and other vital engine components.
Water Absorption: Ethanol, a common additive in gasoline, attracts water. Water in the fuel tank can lead to corrosion and interfere with combustion. Phase separation occurs when too much water is absorbed, creating a layer of water and ethanol at the bottom of the fuel tank.
The lifespan of gasoline depends on storage conditions and fuel composition. Unstabilized gasoline can start to degrade in as little as 30 days. Always use a fuel stabilizer, especially if you’re storing your mower for the winter or longer periods.
Identifying the Symptoms of Bad Gas
Before diving into repairs, confirm that bad gas is indeed the problem. Several telltale signs indicate fuel-related issues.
Difficulty Starting: This is the most common symptom. The engine might crank but fail to ignite or start only after repeated attempts.
Rough Idling: The engine might idle unevenly, sputtering, or stalling frequently.
Loss of Power: The mower might lack power when cutting grass, struggling to maintain a consistent speed.
Unusual Noises: Popping, backfiring, or knocking sounds can indicate improper combustion due to bad gas.
Visible Residue: Check the fuel filter and fuel lines for signs of gummy or varnish-like deposits.
Smell: Stale gas often has a sour or varnish-like odor, quite different from fresh gasoline.
If you observe these symptoms, chances are you’re dealing with a bad gas situation. However, it’s also wise to rule out other potential issues, such as a dirty air filter or a faulty spark plug.
Step-by-Step Guide to Treating a Lawn Mower with Bad Gas
Treating a lawn mower with bad gas involves several steps, from draining the old fuel to cleaning the affected components. Safety is paramount, so always work in a well-ventilated area, wear gloves, and avoid open flames.
Draining the Old Fuel
The first step is to remove the contaminated fuel from the tank. There are several methods to accomplish this.
Using a Siphon: A siphon is a simple and effective tool for removing fuel. Insert one end of the siphon hose into the fuel tank and the other end into an approved gasoline container. Create a siphon action by sucking on the hose (ensure you don’t ingest any fuel!) and let gravity do the rest.
Fuel Tank Drain Plug: Some lawn mowers have a drain plug located at the bottom of the fuel tank. Place a container beneath the plug and carefully loosen it to allow the fuel to drain.
Tilting the Mower: As a last resort, you can carefully tilt the mower over a container to drain the fuel. However, this method is messy and potentially dangerous. Ensure the mower is stable and avoid spilling fuel on yourself or the surrounding area. Disconnect the spark plug wire for safety.
Always dispose of old gasoline properly. Contact your local waste management facility for information on hazardous waste disposal. Never pour gasoline down the drain or into the ground.
Cleaning the Fuel Tank
After draining the fuel, cleaning the tank removes any remaining residue and contaminants.
Rinsing with Fresh Gasoline: Pour a small amount of fresh gasoline into the tank, swish it around to dissolve any deposits, and then drain it completely. Repeat this process a couple of times to ensure thorough cleaning.
Using a Fuel Tank Cleaner: For more stubborn deposits, consider using a commercially available fuel tank cleaner. Follow the manufacturer’s instructions carefully. Ensure the cleaner is compatible with your fuel tank material.
Drying the Tank: Allow the fuel tank to air dry completely before adding fresh fuel. This prevents any remaining moisture from contaminating the new gasoline.
Cleaning the Carburetor
The carburetor is responsible for mixing air and fuel in the correct proportions for combustion. It’s a common victim of bad gas, as its small jets and passages are easily clogged.
Locating the Carburetor: The carburetor is typically located between the air filter and the engine. Refer to your lawn mower’s owner’s manual for specific location and identification.
Removing the Carburetor: Carefully disconnect the fuel lines, linkage, and any other components attached to the carburetor. Take pictures as you disassemble it to aid in reassembly.
Cleaning the Carburetor Components: Disassemble the carburetor and clean each component thoroughly. Use carburetor cleaner spray to dissolve varnish and deposits. Pay close attention to the jets, which are small openings that control fuel flow. Use a small wire or carburetor cleaning tool to clear any blockages.
Reassembling the Carburetor: Reassemble the carburetor in the reverse order of disassembly. Ensure all components are properly seated and tightened. Replace any worn or damaged parts, such as gaskets or O-rings.
Adjusting the Carburetor: After reassembling the carburetor, you may need to adjust the fuel mixture for optimal performance. Consult your lawn mower’s owner’s manual for specific adjustment procedures.
Replacing the Fuel Filter
The fuel filter prevents contaminants from entering the carburetor. If your lawn mower has a fuel filter, replace it regularly, especially after dealing with bad gas.
Locating the Fuel Filter: The fuel filter is typically located in the fuel line between the fuel tank and the carburetor.
Replacing the Filter: Disconnect the fuel lines from the old filter and install the new filter, ensuring the flow direction is correct (indicated by an arrow on the filter).
Checking and Replacing the Spark Plug
A faulty spark plug can also contribute to starting problems. Inspect the spark plug for signs of wear, fouling, or damage.
Removing the Spark Plug: Disconnect the spark plug wire and use a spark plug wrench to remove the spark plug.
Inspecting the Spark Plug: Check the spark plug for signs of carbon buildup, oil fouling, or cracked porcelain. A healthy spark plug should have a clean, dry electrode.
Replacing the Spark Plug: If the spark plug is fouled or damaged, replace it with a new spark plug of the correct type. Consult your lawn mower’s owner’s manual for the correct spark plug specifications.
Gapping the Spark Plug: Before installing the new spark plug, ensure the gap between the electrode and the ground electrode is correct. Use a spark plug gapping tool to adjust the gap to the specified value.
Adding Fresh Fuel and Fuel Stabilizer
After cleaning the fuel system and replacing any necessary components, add fresh gasoline to the fuel tank.
Use Fresh Gasoline: Use gasoline with an octane rating recommended by your lawn mower’s manufacturer.
Add Fuel Stabilizer: Add a fuel stabilizer to the gasoline to prevent future degradation. Follow the manufacturer’s instructions for the correct dosage.
Start the Engine: Prime the engine by pressing the primer bulb a few times (if equipped). Then, attempt to start the engine. It may take a few tries for the engine to start, as the fuel system needs to be primed.
Preventing Future Problems: Best Practices for Fuel Storage
Preventing bad gas is far easier than dealing with its consequences. Follow these best practices for fuel storage to keep your lawn mower running smoothly.
Use Fuel Stabilizer: Always add fuel stabilizer to gasoline, especially when storing your lawn mower for extended periods.
Store Gasoline in Approved Containers: Use approved gasoline containers that are designed to prevent evaporation and leaks.
Store Gasoline in a Cool, Dry Place: Store gasoline in a cool, dry place away from direct sunlight and heat sources.
Use Gasoline Within Six Months: Gasoline starts to degrade after about six months, even with fuel stabilizer. Use gasoline within this timeframe for optimal performance.
Drain Fuel Before Long-Term Storage: If you’re storing your lawn mower for the winter, drain the fuel tank and run the engine until it stalls to remove any remaining fuel from the carburetor.
Troubleshooting Additional Issues
If you’ve followed all the steps above and your lawn mower still isn’t running properly, there may be other underlying issues.
Check the Air Filter: A dirty air filter can restrict airflow and affect engine performance. Clean or replace the air filter as needed.
Inspect the Ignition System: Check the spark plug wire, ignition coil, and other components of the ignition system for damage or corrosion.
Check the Compression: Low compression can indicate worn piston rings or valves. Perform a compression test to assess the engine’s condition.
Seek Professional Help: If you’re unable to diagnose and repair the problem yourself, take your lawn mower to a qualified repair technician.
By understanding the causes of bad gas, recognizing the symptoms, and following the steps outlined in this guide, you can effectively treat a lawn mower suffering from fuel-related problems and keep your lawn looking its best. Remember safety first, and enjoy the satisfaction of a well-maintained machine!
What are the common signs of bad gas in a lawn mower?
Common signs include difficulty starting the mower, sputtering or stalling shortly after starting, and a noticeable lack of power during operation. You might also observe a thick, dark smoke coming from the exhaust or a strong, unusual odor different from fresh gasoline. These symptoms indicate the gas has likely degraded and is no longer combusting efficiently.
Beyond the operational issues, you might visually inspect the gasoline in the tank. Bad gas often appears discolored, ranging from a darker yellow to brown. It may also have a varnish-like consistency and a sour smell, as opposed to the sharp, clean scent of fresh gasoline. These visual and olfactory clues are strong indicators that the fuel needs replacing.
How does bad gas affect a lawn mower’s performance?
Bad gas, especially gasoline that has aged and separated, affects a lawn mower’s performance by hindering proper combustion. The volatile components of gasoline evaporate over time, leaving behind heavier, gummy residues. These residues clog fuel lines, carburetor jets, and other engine components, restricting fuel flow and preventing the engine from running smoothly.
The reduced volatility of aged gasoline also makes it difficult for the engine to start and maintain a stable idle. The fuel may not ignite properly, leading to misfires, stalling, and a general lack of power. In severe cases, the engine may not start at all due to the accumulation of deposits and the compromised quality of the fuel.
What safety precautions should I take when draining bad gas from a lawn mower?
Safety is paramount when handling gasoline. First, ensure the lawn mower engine is completely cool and turned off. Work outdoors or in a well-ventilated area away from any open flames, sparks, or heat sources. This reduces the risk of accidental ignition of the flammable gasoline vapors.
Wear appropriate personal protective equipment, including chemical-resistant gloves and eye protection, to prevent skin and eye irritation from gasoline exposure. Have a UL-approved gasoline container readily available to safely collect the drained fuel. Dispose of the old gasoline properly at a designated hazardous waste collection site or recycling center according to local regulations.
What is the best way to dispose of old gasoline?
The best way to dispose of old gasoline is to take it to a local hazardous waste collection site or recycling center. These facilities are equipped to handle flammable liquids safely and responsibly, preventing environmental contamination. Contact your local municipality or waste management service to find the nearest drop-off location.
Never pour old gasoline down drains, into the sewer system, or onto the ground. This poses significant environmental risks, including soil and water contamination. Avoid burning the gasoline as well, as it releases harmful pollutants into the air. Utilizing designated disposal channels is the safest and most environmentally conscious approach.
How can I clean the fuel system after draining bad gas?
After draining the bad gas, cleaning the fuel system involves several key steps. Start by removing and cleaning the fuel filter, either by replacing it with a new one or rinsing it thoroughly with carburetor cleaner. Next, carefully inspect and clean the carburetor, paying close attention to the jets and passages, using a dedicated carburetor cleaner.
For more thorough cleaning, consider disassembling the carburetor and soaking the individual components in carburetor cleaner. Ensure all parts are completely dry before reassembling. Finally, flush the fuel lines with fresh gasoline to remove any remaining debris. This process helps remove any residue left behind by the old gasoline and ensures a clean fuel supply to the engine.
Can I add a fuel stabilizer to prevent gas from going bad in the future?
Yes, adding a fuel stabilizer is highly recommended to prevent gasoline from going bad, especially if the lawn mower will be stored for an extended period. Fuel stabilizers work by preventing the breakdown and oxidation of gasoline, which are the primary causes of fuel degradation. They also help to prevent the formation of gum and varnish deposits in the fuel system.
To use a fuel stabilizer effectively, add the recommended amount to fresh gasoline before storing the lawn mower. Run the engine for a few minutes to ensure the stabilized fuel circulates through the entire fuel system. This simple step can significantly extend the lifespan of the gasoline and prevent starting problems in the future. Always follow the manufacturer’s instructions for the specific fuel stabilizer product you are using.
How long can gasoline typically last in a lawn mower before going bad?
Unstabilized gasoline typically lasts for approximately 3 to 6 months in a lawn mower before it starts to degrade and lose its combustion properties. Factors such as temperature, humidity, and exposure to air can accelerate this process. The gasoline’s octane rating can decrease over time, leading to reduced engine performance and potential starting issues.
With the addition of a fuel stabilizer, gasoline can remain viable for up to 12 months or even longer, depending on the specific stabilizer used and storage conditions. Storing the lawn mower in a cool, dry place and ensuring the fuel tank is mostly full can also help extend the fuel’s lifespan and prevent it from going bad quickly. Regular use of a fuel stabilizer is a cost-effective way to protect your lawn mower’s engine and ensure reliable starting and performance.