Starting your lawn mower is usually a straightforward task, but sometimes, that familiar pull on the starter cord yields nothing but frustration. One common culprit? Bad gas. Fuel that has deteriorated over time can wreak havoc on your mower’s engine, preventing it from starting. This comprehensive guide will walk you through the steps to diagnose and address the issue of bad gas in your lawn mower, getting you back to maintaining your lawn in no time.
Understanding Bad Gas and Its Impact
Gasoline, unlike fine wine, does not improve with age. Over time, it undergoes a degradation process, particularly when exposed to air and moisture. This degradation can lead to several problems that prevent your lawn mower from starting.
The Science Behind Fuel Degradation
Gasoline is a complex mixture of hydrocarbons. As it sits, the volatile components evaporate, leaving behind a thicker, gum-like residue. This residue can clog fuel lines, carburetors, and other critical engine components. Ethanol, often added to gasoline, further complicates matters. Ethanol attracts water, which can lead to phase separation, where the ethanol and water separate from the gasoline, forming a corrosive mixture that damages the engine. This phase separation is especially problematic during winter storage or extended periods of inactivity.
Symptoms of Bad Gas in Your Lawn Mower
Recognizing the signs of bad gas is crucial for quick diagnosis and resolution. Common symptoms include:
- The mower refusing to start, even after multiple attempts.
- Difficulty starting, with the engine sputtering or running roughly.
- A noticeable decrease in engine power.
- Excessive smoke coming from the exhaust.
- A strong, pungent odor emanating from the fuel tank.
If you observe any of these symptoms, the chances are high that bad gas is the culprit.
Step-by-Step Guide to Starting a Lawn Mower with Bad Gas
Addressing bad gas in your lawn mower involves several key steps, from safely removing the old fuel to cleaning the affected components and replenishing with fresh gasoline.
Safety First: Preparing for the Task
Before you begin, safety is paramount. Gasoline is flammable, and working with it requires caution.
- Work in a well-ventilated area, preferably outdoors.
- Wear safety glasses and gloves to protect your eyes and skin.
- Keep a fire extinguisher nearby in case of emergencies.
- Avoid smoking or working near open flames.
- Disconnect the spark plug wire to prevent accidental starting.
Taking these precautions will help ensure a safe and incident-free experience.
Draining the Old Gas
The first step is to remove the bad gas from the fuel tank. There are several methods to accomplish this:
- Siphoning: Use a siphon pump to draw the gas out of the tank into a suitable container. Ensure the container is gasoline-safe and properly labeled.
- Fuel Line Disconnection: Locate the fuel line connected to the carburetor. Carefully disconnect it and allow the gas to drain into a container. Be prepared for spills and have rags handy.
- Tank Removal (if applicable): Some lawn mowers have removable fuel tanks. If yours does, carefully detach the tank and pour the gas into a container.
Regardless of the method you choose, handle the old gas responsibly. Do not pour it down the drain or onto the ground. Dispose of it properly at a designated recycling center or hazardous waste facility.
Cleaning the Fuel System
Once the old gas is removed, the next step is to clean the fuel system to remove any residue or deposits.
Cleaning the Fuel Tank
Even after draining, residue may remain in the fuel tank. Rinse the tank with a small amount of fresh gasoline to dislodge any remaining debris. Swirl the gas around and then pour it out into the waste container. Allow the tank to air dry completely before proceeding.
Cleaning the Carburetor
The carburetor is a critical component that mixes air and fuel for combustion. It is also a common point of blockage due to bad gas.
- Carburetor Cleaner: Purchase a can of carburetor cleaner from your local auto parts store.
- Disassembly (if comfortable): If you are comfortable disassembling the carburetor, carefully remove it from the engine. Take pictures during disassembly to aid in reassembly.
- Cleaning: Spray carburetor cleaner into all the carburetor’s orifices and passages. Use a small brush or wire to remove stubborn deposits.
- Reassembly: Reassemble the carburetor, referring to your disassembly pictures if needed.
If you are not comfortable disassembling the carburetor, you can try spraying carburetor cleaner directly into the carburetor while the engine is running (if it can run even roughly). Follow the instructions on the carburetor cleaner can.
Cleaning the Fuel Lines
Fuel lines can also become clogged with residue. Disconnect the fuel lines and spray carburetor cleaner through them to dislodge any debris. If the lines are severely clogged, consider replacing them.
Replacing the Fuel Filter
The fuel filter is designed to trap contaminants before they reach the carburetor. If you haven’t replaced it recently, now is an excellent time to do so. A clogged fuel filter can restrict fuel flow and prevent the engine from starting.
- Locate the Fuel Filter: The fuel filter is typically located in the fuel line between the fuel tank and the carburetor.
- Remove the Old Filter: Disconnect the fuel lines from the old filter.
- Install the New Filter: Connect the fuel lines to the new filter, ensuring it is installed in the correct direction (follow the arrow on the filter).
Adding Fresh Gas and Stabilizer
Once the fuel system is clean, it’s time to add fresh gasoline.
- Use Fresh Gasoline: Purchase fresh gasoline from a reputable gas station.
- Add Fuel Stabilizer: Add a fuel stabilizer to the gasoline to prevent future degradation. Fuel stabilizer helps keep the gas fresh for longer periods, especially important if you don’t use your lawn mower frequently. Follow the instructions on the fuel stabilizer bottle for the correct ratio.
- Fill the Tank: Fill the fuel tank with the fresh gasoline mixture.
Attempting to Start the Lawn Mower
After completing all the above steps, it’s time to try starting the lawn mower.
- Reconnect the Spark Plug Wire: Ensure the spark plug wire is securely connected.
- Prime the Engine: If your lawn mower has a primer bulb, press it several times to prime the engine with fuel.
- Start the Engine: Pull the starter cord firmly. It may take several attempts for the engine to start, especially if it has been sitting for a while.
If the lawn mower still doesn’t start after several attempts, there may be other underlying issues, such as a faulty spark plug or a problem with the ignition system.
Preventive Measures to Avoid Bad Gas Problems
Preventing bad gas problems is much easier than dealing with them. By taking a few simple precautions, you can keep your lawn mower running smoothly for years to come.
Using Fuel Stabilizer Regularly
As mentioned earlier, fuel stabilizer is a valuable tool for preventing fuel degradation. Add it to your gasoline every time you fill the tank, especially if you don’t use your lawn mower frequently.
Emptying the Fuel Tank Before Storage
If you plan to store your lawn mower for an extended period, such as during the winter, it’s best to empty the fuel tank completely. This prevents the gas from degrading and causing problems when you try to start the mower again in the spring.
Using Ethanol-Free Gasoline
Ethanol-free gasoline is less prone to water absorption and phase separation than gasoline containing ethanol. If available in your area, consider using ethanol-free gasoline in your lawn mower.
Storing Gasoline Properly
Store gasoline in a tightly sealed, approved container in a cool, dry place away from direct sunlight and heat sources. Avoid storing gasoline for more than a few months, as it will eventually degrade even in optimal storage conditions.
Troubleshooting Starting Issues Beyond Bad Gas
Even after addressing the issue of bad gas, your lawn mower might still refuse to start. Here are some other common causes and how to troubleshoot them:
Spark Plug Problems
A faulty spark plug can prevent the engine from starting. Inspect the spark plug for signs of damage or fouling. If it looks worn or dirty, replace it. Also, check the spark plug gap and adjust it if necessary.
Air Filter Issues
A dirty or clogged air filter can restrict airflow to the engine, making it difficult to start. Inspect the air filter and clean or replace it if necessary.
Ignition System Problems
The ignition system is responsible for generating the spark that ignites the fuel-air mixture. If the ignition system is faulty, the engine won’t start. Test the ignition system with a spark tester to see if it is producing a spark. If not, the ignition coil or other components may need to be replaced.
Compression Problems
Compression is essential for the engine to run. If the engine lacks compression, it won’t start. Compression problems can be caused by worn piston rings, damaged valves, or a blown head gasket. Testing compression requires specialized equipment and knowledge. If you suspect a compression problem, it’s best to consult a qualified mechanic.
Conclusion
Dealing with bad gas in your lawn mower can be frustrating, but by following the steps outlined in this guide, you can diagnose and resolve the problem effectively. Remember to prioritize safety, clean the fuel system thoroughly, and take preventive measures to avoid future issues. By understanding the causes of fuel degradation and implementing proactive maintenance practices, you can keep your lawn mower running smoothly and enjoy a well-maintained lawn for years to come. If, after attempting these solutions, your lawn mower still refuses to start, it might be time to consult a qualified mechanic for professional assistance. They can diagnose more complex issues and perform necessary repairs to get your mower back in working order.
What are the signs that my lawn mower has bad gas?
The most common signs of bad gas in your lawn mower include difficulty starting, sputtering or stalling during operation, a weak engine performance, and the presence of a strong, sour, or varnish-like odor emanating from the fuel tank. You may also notice a gummy or sticky residue around the carburetor and fuel lines, indicating that the fuel has begun to break down and oxidize. These symptoms are all indicators that the fuel is no longer providing the necessary combustion properties for efficient engine operation.
Another sign is the appearance of dark or cloudy fuel in the tank or when you drain it. This discoloration is caused by the formation of gums and varnishes as the gasoline ages and reacts with air and moisture. If you suspect bad gas, it is always best to drain the old fuel and replace it with fresh, stabilized gasoline to prevent further damage to your lawn mower’s engine.
Can I start a lawn mower with bad gas if I just add fresh gas?
Adding fresh gas to a lawn mower with bad gas may provide a temporary improvement, but it is generally not a reliable solution. While fresh gas can dilute the bad gas to some extent, the degraded fuel will still contain contaminants and varnishes that can clog the carburetor and fuel lines, leading to poor engine performance and potential damage over time. It’s analogous to mixing a little bit of clean water with dirty water; it’s still dirty.
The best course of action is to completely drain the old, bad gas from the fuel tank and carburetor before adding fresh, stabilized gasoline. This will ensure that the engine receives a clean supply of fuel and prevent further buildup of harmful deposits. Cleaning the carburetor may also be necessary, depending on the severity of the fuel degradation.
What is the best way to drain bad gas from a lawn mower?
The safest and most effective way to drain bad gas from a lawn mower involves disconnecting the spark plug wire to prevent accidental starting, then locating the fuel drain plug or petcock, usually located at the bottom of the fuel tank or carburetor. Place a suitable container underneath to catch the drained fuel, and carefully open the drain plug or petcock to allow the fuel to flow out.
If your lawn mower does not have a drain plug, you can use a siphon pump or carefully tilt the mower (following safety precautions) to pour the fuel into a container. Be sure to dispose of the used fuel properly at a hazardous waste disposal site or recycling center. Never pour gasoline down drains or into the ground.
What type of fuel stabilizer is recommended for lawn mowers?
For lawn mowers, a fuel stabilizer formulated for small engines and containing ethanol protection is highly recommended. These stabilizers typically contain antioxidants and corrosion inhibitors that prevent fuel degradation, gum formation, and ethanol-related issues like water absorption and phase separation. Look for products specifically labeled for use in 2-cycle or 4-cycle engines, depending on your lawn mower’s engine type.
Popular and effective fuel stabilizers include brands like STA-BIL Storage Fuel Stabilizer, Sea Foam Motor Treatment, and Lucas Oil Fuel Stabilizer. Always follow the manufacturer’s instructions regarding the correct dosage and application frequency. Adding fuel stabilizer to your gas can significantly extend the fuel’s shelf life and prevent costly repairs.
How often should I replace the fuel filter on my lawn mower?
Replacing the fuel filter on your lawn mower annually or every 100 hours of operation is generally recommended. A clogged or dirty fuel filter can restrict fuel flow to the carburetor, leading to poor engine performance, difficulty starting, and potential engine damage. Regular replacement ensures a clean and consistent fuel supply.
The frequency may need adjustment based on the operating conditions and the quality of fuel used. If you frequently operate in dusty or dirty environments or use non-stabilized fuel, you may need to replace the fuel filter more often. Inspect the fuel filter regularly for signs of contamination or blockage, and replace it if necessary.
What are the risks of running a lawn mower with bad gas?
Running a lawn mower with bad gas poses several risks to the engine’s health and performance. The degraded fuel can cause the formation of gums and varnishes that clog the carburetor jets and fuel lines, leading to poor engine performance, difficulty starting, and even complete engine failure. The engine may also run rough, sputter, or stall frequently.
Furthermore, bad gas can damage the fuel system components, including the fuel pump, fuel filter, and rubber hoses. In severe cases, it can even lead to corrosion and damage to internal engine parts, such as the pistons, cylinders, and valves. Prolonged use of bad gas can result in costly repairs or the need for a complete engine replacement.
What are some preventative measures to avoid bad gas in my lawn mower?
The most effective preventative measure to avoid bad gas is to use fresh gasoline and add a fuel stabilizer when storing the lawn mower for extended periods, such as during the off-season. Fuel stabilizers prevent the gasoline from breaking down and forming harmful deposits. Properly storing the fuel container itself is also critical. Use a sealed container and store it in a cool, dark, and dry place.
Another good practice is to avoid purchasing more gasoline than you will use within a reasonable timeframe, typically within 30 to 60 days. Ethanol-blended fuels are especially susceptible to degradation, so using ethanol-free gasoline, if available, can also help prevent fuel-related problems. Finally, always drain the fuel tank and run the carburetor dry before storing the lawn mower for extended periods.