The sun is shining, the birds are chirping, and you’re finally ready to tackle that overgrown lawn. But as you pull the starter cord, your lawn mower roars to life for a fleeting moment, only to sputter and die. Frustration sets in, leaving you wondering what’s gone wrong with your trusty machine. This article explores the common culprits behind a lawn mower starting and then stopping, providing you with the knowledge and troubleshooting steps to get your mower back in action quickly and efficiently.
In essence, a lawn mower that starts then stops indicates a problem with the fuel system, ignition system, or air intake. A lack of fuel, spark, or adequate air can all contribute to this frustrating issue. The specific cause often depends on the type of lawn mower you own, as well as the symptoms you observe.
Understanding the Basics: Fuel, Spark, and Air
To run smoothly, a gasoline-powered lawn mower requires a consistent supply of three essential elements:
- Fuel: The fuel provides the energy to power the engine.
- Spark: The spark ignites the fuel-air mixture, causing combustion.
- Air: Air mixes with the fuel, creating a combustible mixture.
When any of these elements are compromised, the engine can struggle to start or run properly. Let’s delve deeper into common reasons why your lawn mower may be starting then stopping.
Fuel System Issues
1. Empty Fuel Tank
The most straightforward reason for a lawn mower starting and then stopping is simply an empty fuel tank. This may seem obvious, but it’s easy to overlook, especially if you’ve been using the mower frequently. Always check the fuel level before starting your mower to avoid this simple mistake.
2. Bad Gas
Old or contaminated gasoline can cause a variety of problems, including difficulty starting and stalling. Ethanol, a common additive in gasoline, attracts moisture, which can lead to fuel degradation.
Symptoms:
- Rough running: The engine may sputter and run unevenly.
- Difficulty starting: The mower may take longer to start or require multiple pulls.
Solution:
- Drain the old fuel: Carefully drain the fuel tank and dispose of it properly.
- Refill with fresh fuel: Use fresh, high-quality gasoline, preferably with a fuel stabilizer.
3. Clogged Fuel Lines or Filters
Over time, fuel lines and filters can become clogged with debris or sediment, restricting the flow of fuel to the engine.
Symptoms:
- Consistent stalling: The mower starts but stalls after a short period.
- Difficulty starting: The mower may take a long time to start or require multiple pulls.
Solution:
- Inspect the fuel lines: Check the fuel lines for any kinks, cracks, or blockages.
- Replace the fuel filter: Replace the fuel filter regularly, as recommended by the manufacturer.
4. Fuel Pump Issues
The fuel pump draws fuel from the tank and delivers it to the carburetor. If the fuel pump is malfunctioning, the engine may not receive enough fuel to run properly.
Symptoms:
- Stalling: The mower may stall suddenly, especially under load.
- Difficulty starting: The mower may be difficult to start, especially after it has been sitting for a while.
Solution:
- Test the fuel pump: Use a fuel pressure gauge to test the fuel pump’s pressure.
- Replace the fuel pump: If the fuel pump is not functioning correctly, it will need to be replaced.
Ignition System Problems
1. Dirty or Worn Spark Plug
The spark plug ignites the fuel-air mixture in the combustion chamber. A dirty or worn-out spark plug can prevent the spark from reaching the mixture, causing the engine to stop.
Symptoms:
- Difficulty starting: The mower may require multiple pulls to start.
- Engine misfires: The engine may run rough or sputter.
- Black smoke: The engine may produce black smoke from the exhaust.
Solution:
- Clean or replace the spark plug: Remove the spark plug, clean it with a wire brush, or replace it with a new one.
2. Faulty Ignition Coil
The ignition coil generates the high-voltage spark that ignites the fuel-air mixture. If the ignition coil fails, the engine will not be able to run.
Symptoms:
- No spark: The engine will not start at all.
- Intermittent stalling: The engine may stall randomly.
Solution:
- Test the ignition coil: Use a spark tester to check if the ignition coil is producing a spark.
- Replace the ignition coil: If the coil is faulty, it will need to be replaced.
Air Intake Problems
1. Clogged Air Filter
The air filter prevents dirt and debris from entering the engine. A clogged air filter restricts airflow to the engine, causing it to run poorly or stall.
Symptoms:
- Difficulty starting: The mower may take longer to start or require multiple pulls.
- Loss of power: The engine may lose power or sputter.
- Black smoke: The engine may produce black smoke from the exhaust.
Solution:
- Clean or replace the air filter: Regularly clean or replace the air filter as recommended by the manufacturer.
2. Blocked Air Intake
The air intake allows fresh air to enter the engine. A blockage in the air intake, such as a bird’s nest or debris, can prevent the engine from receiving enough air to run.
Symptoms:
- Difficulty starting: The mower may take a long time to start or require multiple pulls.
- Stalling: The engine may stall suddenly.
- Engine misfires: The engine may run rough or sputter.
Solution:
- Inspect the air intake: Check the air intake for any obstructions.
- Clear any blockage: Remove any debris or obstacles from the air intake.
Other Possible Causes
While the issues mentioned above are among the most common causes of a lawn mower starting then stopping, other factors can contribute to this problem. These include:
- Battery problems (for electric start mowers): A weak or dead battery can prevent the engine from starting.
- Choke problems: The choke is used to enrich the fuel mixture when starting the engine. If the choke is not working properly, the engine may stall.
- Carburetor problems: A dirty or malfunctioning carburetor can cause a variety of problems, including starting and stalling issues.
- Engine overheating: An overheated engine can cause the mower to stop running.
Troubleshooting Tips
If your lawn mower starts then stops, it can be frustrating to pinpoint the exact cause. However, by following these troubleshooting tips, you can increase your chances of identifying the problem and getting your mower back in working order.
- Check the obvious: Ensure the fuel tank is full, the spark plug is clean and in good condition, and the air filter is clean or replaced.
- Start with the simplest solutions: Try replacing the spark plug, cleaning the fuel lines and filter, or clearing any obstructions from the air intake.
- Observe the symptoms: Pay close attention to the mower’s performance. Does it stall immediately after starting? Does it run for a short period before stopping?
- Consult the owner’s manual: Refer to the owner’s manual for troubleshooting tips and specific information on your mower model.
- Seek professional help: If you’re unable to identify the problem, it’s best to seek assistance from a qualified mechanic.
Prevention is Key
The best way to avoid a lawn mower starting then stopping is to practice regular maintenance.
- Use fresh fuel: Always use fresh, high-quality gasoline in your lawn mower.
- Change the fuel filter regularly: Replace the fuel filter at least once a year or more frequently if you use your mower often.
- Clean or replace the air filter: Regularly clean or replace the air filter as recommended by the manufacturer.
- Maintain the spark plug: Clean or replace the spark plug regularly.
- Store your mower properly: During the off-season, store your mower in a dry, well-ventilated area and drain the fuel tank.
Conclusion
A lawn mower that starts then stops can be a frustrating problem, but it’s often a sign of a simple issue that can be easily resolved. By understanding the basics of fuel, spark, and air, you can effectively troubleshoot common problems. Remember to perform regular maintenance to prevent future issues and keep your lawn mower running smoothly. If you’re unsure about the problem, don’t hesitate to seek assistance from a qualified mechanic. With a little effort, you’ll soon be back to enjoying a perfectly manicured lawn.
FAQs
Why does my lawnmower start then stop?
This is a common issue that can be caused by a few different things. The most common culprits are a clogged air filter, a dirty carburetor, or a lack of fuel. If your lawnmower is starting but then stopping, the first thing to do is check the air filter. If it is dirty or clogged, it will restrict the flow of air to the engine, causing it to stall.
To clean the air filter, simply remove it from the mower and tap it against a hard surface to remove any loose debris. If the filter is heavily soiled, you may need to wash it with soap and water. Let the filter dry completely before reinstalling it in the mower.
How do I clean the carburetor?
If the air filter is clean, the next thing to check is the carburetor. The carburetor is responsible for mixing fuel and air, and if it is dirty, it can cause the engine to run poorly or stall. To clean the carburetor, you will need to remove it from the mower and disassemble it.
Once you have disassembled the carburetor, use a carburetor cleaner spray to clean all of the parts. Be sure to pay close attention to the jets, as these can become easily clogged. Once the parts are clean, reassemble the carburetor and reinstall it in the mower.
What if I have enough fuel?
If you have enough fuel, and the air filter and carburetor are clean, the problem may be with the spark plug. The spark plug is responsible for igniting the fuel-air mixture in the engine, and if it is fouled or damaged, it can prevent the engine from running properly.
To check the spark plug, remove it from the mower and inspect it. If the spark plug is fouled, you can clean it with a wire brush. If the spark plug is damaged, you will need to replace it with a new one.
Why does my lawnmower stop when I try to mow?
If the lawnmower starts but then stops when you try to mow, the problem may be with the clutch. The clutch is responsible for transferring power from the engine to the wheels, and if it is slipping, it can cause the engine to stall.
To check the clutch, start the mower and observe the blades. If the blades are not spinning, the clutch is not engaging. If the blades are spinning but the mower is not moving, the clutch is slipping.
How do I fix the clutch?
To fix the clutch, you may need to adjust it or replace it. To adjust the clutch, you will need to loosen the adjustment nut and turn the adjustment screw until the clutch engages. If the clutch is still slipping, you will need to replace it.
What if my lawnmower is overheating?
If your lawnmower is overheating, it can cause the engine to stall. Overheating can be caused by a few different things, including a clogged air filter, a lack of oil, or a faulty cooling system.
To fix an overheating lawnmower, check the air filter, add oil if needed, and check the cooling system. If the cooling system is faulty, you will need to repair or replace it.
What if my lawnmower is getting old?
If your lawnmower is old, it may be time to replace it. Old lawnmowers can be unreliable and expensive to repair. If your lawnmower is constantly breaking down, it may be time to invest in a new one.