Starting a small lawn mower might seem straightforward, but understanding the process and potential pitfalls can save you time, frustration, and even costly repairs. This guide provides a detailed walkthrough, covering everything from basic preparations to troubleshooting common starting problems.
Preparing Your Lawn Mower for Starting
Before you even think about pulling the starter cord, taking a few preliminary steps is crucial. These preparations ensure a smoother start and prolong the life of your mower.
Checking the Fuel Level
Perhaps the most obvious, but often overlooked, step is verifying the fuel level. A lawn mower won’t start without gasoline. Make sure the fuel tank has an adequate amount of fresh gasoline. Using old or stale fuel is a common cause of starting problems. Consider using a fuel stabilizer, especially if the mower has been sitting idle for an extended period. This prevents the gasoline from degrading and forming gum and varnish deposits that can clog the carburetor.
Inspecting the Oil Level
Engine oil is the lifeblood of your lawn mower’s engine. Always check the oil level before each use. Locate the dipstick, usually near the engine. Remove it, wipe it clean, reinsert it fully, and then remove it again to check the oil level. The oil level should be between the “min” and “max” marks on the dipstick. If the oil is low, add the appropriate type of oil as specified in your owner’s manual.
Examining the Air Filter
A clean air filter is essential for proper engine performance. A dirty or clogged air filter restricts airflow, making it difficult for the engine to start and run efficiently. Regularly inspect and clean or replace the air filter. The frequency of cleaning or replacement depends on the operating conditions, but generally, cleaning every 25 hours of use and replacing it annually is a good practice. Most air filters are easily accessible and can be cleaned with compressed air or washed with soap and water. Allow the filter to dry completely before reinstalling it.
Verifying the Spark Plug
The spark plug ignites the air-fuel mixture in the engine’s cylinder. A faulty or fouled spark plug can prevent the engine from starting. Check the spark plug for signs of wear, damage, or carbon buildup. If the spark plug is dirty, clean it with a wire brush or spark plug cleaner. If it’s damaged or heavily worn, replace it with a new spark plug of the correct type. The owner’s manual will specify the correct spark plug for your mower. When reinstalling the spark plug, ensure it’s tightened to the correct torque specification.
The Starting Procedure: Step-by-Step
Now that you’ve prepared your lawn mower, let’s go through the actual starting procedure. The specific steps may vary slightly depending on the model of your mower, but the general principles remain the same.
Priming the Engine
Many small lawn mowers have a primer bulb that needs to be pressed several times before starting. The primer bulb injects a small amount of fuel directly into the carburetor, making it easier to start the engine. Typically, you’ll need to press the primer bulb three to five times, allowing a few seconds between each press. Over-priming can flood the engine, making it difficult to start. If you suspect you’ve over-primed the engine, wait a few minutes for the excess fuel to evaporate before attempting to start it again.
Setting the Throttle
The throttle control regulates the engine speed. For starting, it’s usually best to set the throttle to the “fast” or “start” position. Consult your owner’s manual for the specific throttle setting recommended for starting. Some mowers have a choke lever that needs to be engaged for starting a cold engine. The choke restricts airflow to the carburetor, enriching the air-fuel mixture and making it easier to start. Once the engine starts, gradually disengage the choke.
Pulling the Starter Cord
This is where the real work begins. Grip the starter cord handle firmly and pull it with a smooth, steady motion. Avoid yanking the cord forcefully, as this can damage the starter mechanism. Pull the cord until you feel resistance, then give it a strong, controlled pull. The engine should either start immediately or sputter slightly. If the engine doesn’t start on the first pull, let the cord retract slowly and repeat the process. Avoid letting the cord snap back quickly, as this can also damage the starter mechanism.
Adjusting the Choke (If Applicable)
If your mower has a choke lever, you may need to adjust it after the engine starts. Gradually disengage the choke as the engine warms up. If you disengage the choke too quickly, the engine may stall. If the engine is running rough, try adjusting the choke slightly until it runs smoothly. Once the engine is fully warmed up, the choke should be completely disengaged.
Troubleshooting Common Starting Problems
Even with proper preparation and technique, your lawn mower might still refuse to start. Here are some common problems and their potential solutions.
Engine Won’t Start at All
If the engine doesn’t even sputter when you pull the starter cord, there could be several reasons.
- No Fuel: Double-check the fuel level in the tank. Even if the gauge shows fuel, there might not be enough to reach the carburetor.
- Spark Plug Issues: A faulty or fouled spark plug is a common culprit. Remove the spark plug, inspect it, and clean or replace it as necessary.
- Ignition Problems: The ignition system might be malfunctioning. This could be due to a faulty ignition coil or a broken wire. Testing the ignition system requires specialized tools and knowledge, so it’s best to consult a qualified mechanic.
- Safety Switch Issues: Most lawn mowers have safety switches that prevent the engine from starting if the operator presence control lever is not engaged or if the bag is not properly attached. Make sure all safety switches are properly engaged.
Engine Starts but Stalls Immediately
If the engine starts briefly but then stalls, it could be due to:
- Fuel Delivery Problems: The carburetor might be clogged or the fuel line might be blocked. Cleaning or replacing the carburetor might be necessary. Also, check the fuel filter for any obstructions.
- Choke Problems: If the choke is not properly adjusted, the engine might not be getting the correct air-fuel mixture. Adjust the choke as needed.
- Vacuum Leaks: A vacuum leak can disrupt the air-fuel mixture and cause the engine to stall. Inspect the intake manifold and vacuum lines for any cracks or leaks.
Engine Runs Rough
If the engine starts and runs, but it runs rough or misfires, it could be due to:
- Dirty Air Filter: A dirty air filter can restrict airflow and cause the engine to run poorly. Clean or replace the air filter.
- Spark Plug Issues: A faulty or fouled spark plug can also cause the engine to run rough. Check the spark plug and clean or replace it.
- Carburetor Problems: A dirty or improperly adjusted carburetor can cause the engine to run rough. Cleaning or adjusting the carburetor might be necessary.
Flooded Engine
If you’ve over-primed the engine, it can become flooded with fuel. This makes it difficult to start.
- Wait it out: The easiest solution is often to wait. Remove the spark plug and pull the starter cord several times to help clear the excess fuel from the cylinder. Allow the engine to sit for 15-20 minutes to allow the fuel to evaporate.
- Bypass Priming: Try starting the engine without priming it. Set the throttle to the “fast” position and pull the starter cord.
Long-Term Maintenance for Easy Starting
Preventive maintenance is key to ensuring your lawn mower starts easily every time.
Regular Cleaning
Keep your lawn mower clean, especially the engine and carburetor area. Dirt and debris can accumulate and cause problems.
Fuel Stabilizer
When storing your lawn mower for extended periods, add fuel stabilizer to the gasoline to prevent it from degrading.
Sharpening the Blade
A sharp blade reduces the load on the engine, making it easier to start and run efficiently.
Professional Servicing
Consider having your lawn mower professionally serviced annually to ensure it’s in good working order. A qualified technician can identify and address potential problems before they cause starting issues.
By following these tips and procedures, you’ll be well-equipped to start your small lawn mower quickly and easily, minimizing frustration and maximizing your lawn-mowing efficiency. Remember to always consult your owner’s manual for specific instructions and recommendations for your model.
Why won’t my lawn mower start even though it has gas?
Even if your lawn mower has gas, several issues could prevent it from starting. First, the fuel might be stale, especially if it’s been sitting in the tank for several months. Gasoline degrades over time, losing its combustion properties. Second, the spark plug might be dirty or damaged, hindering the ignition process. A dirty air filter can also restrict airflow to the engine, preventing it from starting properly.
Check the age of the gasoline and replace it with fresh fuel if necessary. Inspect the spark plug for carbon buildup or damage, cleaning or replacing it as needed. Examine the air filter and clean or replace it if it’s clogged with dirt and debris. These are common culprits when a lawn mower refuses to start despite having fuel.
How often should I change the oil in my lawn mower?
The frequency of oil changes for your lawn mower depends on usage. As a general rule, you should change the oil every 25 to 50 hours of use, or at least once a year, whichever comes first. Regular oil changes are critical for maintaining engine performance and prolonging the life of your lawn mower.
Old oil becomes contaminated with dirt, debris, and metal particles, reducing its ability to lubricate the engine’s moving parts effectively. This can lead to increased friction, overheating, and ultimately, engine damage. Consistent oil changes ensure optimal engine performance and longevity.
What type of gasoline should I use in my lawn mower?
Most lawn mowers require regular unleaded gasoline with an octane rating of 87 or higher. It’s crucial to avoid using gasoline with ethanol content higher than 10% (E10), as ethanol can damage the fuel system components over time. The best option is often non-ethanol gasoline, if available.
Ethanol attracts moisture, which can lead to corrosion and other problems within the engine and fuel lines. Look for gasoline specifically formulated for small engines, as these fuels often contain additives that help stabilize the fuel and prevent corrosion. Always check your owner’s manual for specific fuel recommendations for your model.
How do I clean or replace the air filter on my lawn mower?
Cleaning or replacing the air filter is a simple process that can significantly improve your lawn mower’s performance. First, locate the air filter housing, usually on top of the engine. Remove the cover and take out the air filter.
If the filter is foam, wash it with mild detergent and water, then squeeze out the excess water and allow it to dry completely before reinstalling. If it’s a paper filter, gently tap it against a hard surface to remove loose dirt and debris. If the filter is excessively dirty or damaged, replace it with a new one. Ensure the filter is properly seated in the housing before replacing the cover.
Why is my lawn mower smoking?
Lawn mower smoke can indicate several problems. Blue smoke often means the engine is burning oil, which could be due to worn piston rings or valve seals. White smoke usually indicates that water or coolant is entering the combustion chamber. Black smoke suggests that the engine is running too rich, meaning there’s too much fuel in the air-fuel mixture.
Overfilling the oil can also cause smoking, as the excess oil can get into the combustion chamber. Check the oil level and drain any excess if necessary. If the smoking persists, it’s essential to diagnose the root cause and address it promptly to prevent further engine damage. Consult a qualified mechanic if you’re unsure how to proceed.
How do I sharpen the blade on my lawn mower?
Sharpening the lawn mower blade is crucial for a clean and efficient cut. Disconnect the spark plug wire to prevent accidental starting. Remove the blade from the mower, noting its original orientation for proper reinstallation.
Secure the blade in a vise and use a file or a bench grinder to sharpen the cutting edges, maintaining the original angle. Be careful not to overheat the blade during grinding, as this can weaken the metal. Balance the blade after sharpening using a blade balancer to ensure even weight distribution, which reduces vibration and stress on the mower.
What should I do to prepare my lawn mower for winter storage?
Properly preparing your lawn mower for winter storage is essential to prevent damage and ensure it starts easily in the spring. First, drain the fuel tank completely or add a fuel stabilizer to prevent fuel degradation. Run the engine until it stalls to ensure the carburetor is empty.
Change the oil and replace the air filter to remove contaminants that could cause corrosion during storage. Clean the underside of the mower deck to remove grass clippings and debris. Store the mower in a dry, protected area, such as a garage or shed, to prevent rust and weather damage. Disconnect the spark plug wire and remove the battery (if applicable) for separate storage in a cool, dry place.