There’s nothing more frustrating than starting your lawn mower, only to have it sputter and die a few moments later. Whether you’re a seasoned homeowner or a novice gardener, a malfunctioning lawn mower can quickly turn your weekend chores into an exercise in exasperation. But fear not! This comprehensive guide will equip you with the knowledge to diagnose and troubleshoot common reasons why your lawn mower won’t stay running. We’ll explore potential culprits, from fuel-related issues to spark plug problems, and provide practical solutions to get your mower back in working order.
In a nutshell, a lawn mower that won’t stay running can be caused by a variety of factors, including:
- Fuel-related issues: Old or contaminated fuel, a clogged fuel filter, or a faulty fuel pump can all hinder fuel delivery.
- Spark plug problems: A fouled spark plug or a gap that’s out of adjustment can prevent the engine from igniting properly.
- Air intake problems: A clogged air filter or a damaged air intake can restrict airflow to the engine.
- Ignition system problems: A faulty ignition coil or a broken ignition wire can disrupt the spark needed to start and maintain engine operation.
- Engine problems: A worn-out engine, a broken valve, or a damaged carburetor can all lead to engine failure.
Fuel Trouble: The Most Common Culprit
Fuel issues are the most common reason why a lawn mower won’t stay running. Over time, gasoline can deteriorate, losing its volatility and becoming difficult to ignite. Here’s a breakdown of the common fuel-related problems and how to address them:
1. Old Fuel:
The Problem: Gasoline starts to degrade after about 30 days, and its ability to ignite effectively decreases even further after a few months. Old fuel can leave gummy deposits in the carburetor and fuel lines, hindering proper fuel flow.
The Solution:
- Drain the old fuel: Remove the fuel tank cap and carefully drain the old fuel into a suitable container. You can use a siphon pump or a small hose. Dispose of the old fuel properly according to local regulations.
- Fill with fresh fuel: Fill the tank with fresh, high-quality gasoline. Consider using fuel stabilizer to prevent future degradation, especially if you’re storing your mower for extended periods.
2. Clogged Fuel Filter:
The Problem: The fuel filter is a small but crucial component that traps debris and prevents it from entering the carburetor. A clogged fuel filter can restrict fuel flow, preventing the engine from getting the necessary amount of fuel.
The Solution:
- Locate the fuel filter: It’s typically a small, cylindrical object found near the fuel tank or the fuel line. Refer to your mower’s manual for the exact location.
- Replace the fuel filter: If the filter appears dirty or clogged, replace it with a new one.
3. Faulty Fuel Pump:
The Problem: The fuel pump is responsible for drawing fuel from the tank and delivering it to the carburetor. A faulty fuel pump can either fail to deliver fuel entirely or deliver it inconsistently, resulting in engine stalling.
The Solution:
- Inspect the fuel pump: Check for any visible damage or leaks.
- Replace the fuel pump: If you suspect the fuel pump is faulty, replace it with a new one. Consult your mower’s manual for the correct replacement pump.
Spark Trouble: When the Engine Won’t Ignite
The spark plug plays a vital role in igniting the air-fuel mixture in the combustion chamber. If the spark plug isn’t working properly, your lawn mower won’t start or will stall shortly after starting.
1. Fouled Spark Plug:
The Problem: Over time, carbon and other deposits can accumulate on the spark plug electrodes, creating a gap that hinders the spark. A fouled spark plug will make it difficult for the engine to ignite the fuel.
The Solution:
- Clean or replace the spark plug: Remove the spark plug from the engine using a spark plug wrench. If it’s fouled, you can try cleaning it with a wire brush. However, if the electrode is badly corroded or worn, it’s best to replace the spark plug.
- Check the spark plug gap: Use a spark plug gap tool to check the distance between the electrodes. The correct gap should be listed in your mower’s manual. If the gap is too small or too large, adjust it accordingly.
2. Broken or Damaged Ignition Wire:
The Problem: The ignition wire carries the electrical current from the ignition coil to the spark plug. If the wire is broken or damaged, it will prevent the spark plug from receiving the necessary electrical charge.
The Solution:
- Inspect the ignition wire: Check the wire for any signs of damage, such as cracks, fraying, or loose connections.
- Replace the ignition wire: If the wire is damaged, replace it with a new one. Be sure to disconnect the spark plug wire before working on the ignition system.
Air Intake Woes: The Engine Needs to Breathe
The engine needs a constant supply of fresh air to function correctly. An obstruction in the air intake can restrict airflow and lead to engine problems.
1. Clogged Air Filter:
The Problem: The air filter prevents dirt and debris from entering the engine. Over time, it can become clogged with dust and other particles, restricting airflow to the engine.
The Solution:
- Clean or replace the air filter: Remove the air filter and inspect it. If it’s dirty, you can try cleaning it with compressed air or by washing it with soap and water. If the filter is severely damaged or beyond cleaning, replace it with a new one.
2. Damaged Air Intake:
The Problem: The air intake is the passageway that allows air to enter the engine. If the air intake is damaged or obstructed, it can restrict airflow and cause the engine to stall.
The Solution:
- Inspect the air intake: Check for any damage, cracks, or obstructions.
- Repair or replace the air intake: If the air intake is damaged, it may need to be repaired or replaced.
Ignition System Malfunctions: A Spark is Essential
The ignition system is responsible for generating the spark that ignites the fuel-air mixture. If the ignition system is malfunctioning, the engine won’t start or will stall shortly after starting.
1. Faulty Ignition Coil:
The Problem: The ignition coil transforms low-voltage current from the battery into high-voltage current that powers the spark plug. A faulty ignition coil can fail to produce the necessary high voltage, preventing the engine from starting.
The Solution:
- Check for spark: Disconnect the spark plug wire from the spark plug and hold it near a grounded metal object. Have someone crank the engine while you observe the spark plug wire. If there is no spark, the ignition coil may be faulty.
- Replace the ignition coil: If the ignition coil is faulty, replace it with a new one.
2. Broken Ignition Wire:
The Problem: The ignition wire carries the high-voltage current from the ignition coil to the spark plug. If the wire is broken, it will prevent the spark plug from receiving the high voltage necessary for ignition.
The Solution:
- Inspect the ignition wire: Check the wire for any signs of damage, such as cracks, fraying, or loose connections.
- Replace the ignition wire: If the wire is damaged, replace it with a new one.
Engine Troubles: When the Heart of the Mower Fails
While the issues above are common culprits, sometimes the problem lies within the engine itself.
1. Worn-Out Engine:
The Problem: Like any mechanical device, a lawn mower engine experiences wear and tear over time. Worn-out components, such as piston rings, valves, or bearings, can lead to decreased engine performance and eventually cause the engine to fail.
The Solution: A worn-out engine often requires a complete overhaul or replacement. This is usually a complex task best left to a qualified mechanic.
2. Broken Valve:
The Problem: The valves in the engine control the flow of air and exhaust gases. A broken valve can prevent the engine from running smoothly or even cause it to stall completely.
The Solution: A broken valve typically requires a repair or replacement by a qualified mechanic.
3. Damaged Carburetor:
The Problem: The carburetor mixes fuel and air to create the combustible mixture. A damaged carburetor can lead to incorrect fuel-air ratios, affecting engine performance and causing stalling.
The Solution: Depending on the severity of the damage, the carburetor may need to be cleaned, adjusted, or replaced.
Taking a Proactive Approach
While troubleshooting your lawn mower’s problems can be satisfying, taking preventative measures can save you headaches in the long run.
- Regular maintenance: Clean or replace the air filter, spark plug, and fuel filter regularly.
- Use high-quality fuel: Use fresh gasoline with a high octane rating, and consider using a fuel stabilizer to prevent fuel degradation.
- Store your mower properly: During the off-season, drain the fuel tank, clean the mower, and store it in a dry, covered space.
By understanding the common causes of a lawn mower that won’t stay running, you can approach troubleshooting with confidence. Armed with this knowledge, you can tackle the problem head-on and get your mower back in action quickly. And remember, if you’re unsure about any repair, don’t hesitate to consult a qualified mechanic for assistance.
Frequently Asked Questions
Why won’t my lawnmower stay running?
This is a common problem that can be caused by a number of factors. The most likely culprit is a fuel-related issue, such as a clogged fuel filter or a bad carburetor. However, it could also be an ignition problem, like a faulty spark plug or a broken ignition coil. If your lawnmower is still relatively new, it could also be a simple matter of not having enough fuel in the tank.
If you’re having trouble with your lawnmower, it’s always a good idea to start by checking the simple things first. Make sure you have enough gas in the tank, and check the fuel filter to see if it’s clogged. If neither of these fixes the problem, then you’ll need to start troubleshooting the ignition system.
What are some common causes of a lawnmower not staying running?
As mentioned above, the most common causes of a lawnmower not staying running are fuel-related issues, such as a clogged fuel filter or a bad carburetor. Another common problem is a faulty spark plug. A spark plug that is fouled or worn can prevent the engine from igniting the fuel properly.
Finally, a clogged air filter can also cause a lawnmower to stall. A clogged air filter restricts airflow to the engine, which can prevent the engine from getting enough air to run properly. If you suspect any of these issues are causing your lawnmower to die, try cleaning or replacing the affected parts.
How can I troubleshoot a lawnmower that won’t stay running?
The first step in troubleshooting a lawnmower that won’t stay running is to check the fuel system. Make sure the fuel tank is full and that the fuel line is clear. You can also check the fuel filter to see if it is clogged. If the fuel system is in good condition, you can then check the ignition system.
Check the spark plug to make sure it is clean and that there is a good spark. You can also check the ignition coil to see if it is working properly. If the ignition system is in good condition, the problem may be with the carburetor. You can try cleaning the carburetor or replacing it if it is damaged.
How do I check the fuel filter?
To check the fuel filter, you will need to locate it. The fuel filter is typically located near the fuel tank or the carburetor. Once you have located the fuel filter, you can remove it and inspect it. The fuel filter should be clean and free of debris. If the fuel filter is dirty or clogged, you will need to replace it.
You can usually just twist the filter off and replace it with a new one. If the fuel filter seems okay, you may have another issue. There are various fuel filter types, so be sure to consult your owner’s manual for the proper filter for your lawnmower.
How do I check the spark plug?
To check the spark plug, you will need to remove it from the engine. Once you have removed the spark plug, you can inspect it. The spark plug should be clean and free of carbon buildup. If the spark plug is dirty or fouled, you will need to clean it or replace it.
To check for a spark, you can hold the spark plug against the engine block while someone starts the engine. You should see a spark jump between the spark plug and the engine block. If you don’t see a spark, the spark plug or the ignition system may be faulty.
How do I clean the carburetor?
To clean the carburetor, you will need to remove it from the engine. Once you have removed the carburetor, you can disassemble it and clean the various parts. You will need to use a carburetor cleaner to clean the parts. Be sure to follow the instructions on the carburetor cleaner bottle.
Once you have cleaned the parts, you can reassemble the carburetor and install it back on the engine. After cleaning the carburetor, you’ll need to check if the lawnmower is running properly. If not, you may have a different issue, and a professional mechanic may be needed.
What should I do if I’m still having trouble with my lawnmower?
If you’ve tried all of the troubleshooting steps above and your lawnmower still won’t stay running, you may need to take it to a qualified mechanic. A mechanic can diagnose the problem and make the necessary repairs.
It’s always a good idea to consult your lawnmower’s owner’s manual for specific troubleshooting instructions. The manual will provide valuable information about the specific model of your lawnmower.