A smooth functioning lawn mower is essential to keep the lawn clean. However, sometimes a lawn mower may experience disruptions in its functioning. One of the common problems lawnmowers face is that they Rev up and down while running. The reason lawn mower Revs up and down or fluctuates is because it is facing a condition called idle surge.
It occurs when the engine is just surging and its governor fails to maintain a steady speed. This could be due to a clogged air filter, a defective spark plug, or a loose carburettor. Hence, the lawn mower needs to be cleaned at regular intervals to keep it working smoothly. Moreover, it needs proper maintenance to run effectively.
In this guide, we aim to provide you with the knowledge of what causes the lawn mower to fluctuate, how to prevent idle surge, and practical steps to troubleshoot and diagnose it to ensure the reliable operation of your lawn mower.
Why does my lawn mower keep fluctuating?
If your lawn mower’s engine is fluctuating there might be some causes that are forcing it to do so. Hence, these causes need to be identified as soon as possible. If you will not fix these issues they will end up deteriorating the lawn mower completely. Let’s dive into the topic to get a more detailed understanding of this:
1. Clogged Air Filter
A lawn mower needs a sufficient amount of clean air for the combustion of fuel and smooth running. An air filter is a crucial component of a lawn mower. It ensures a clean air supply to the combustion chamber. It does this by filtering dust, debris, and other air contaminants.
If the air filter gets clogged, it fails to filter air anymore. Consequently, air pollutants will enter the combustion chamber. As a result, the fuel becomes contaminated. This causes the engine to suddenly get too fast or too slow while running. Therefore, an obstructed air filter should be cleaned to avoid engine fluctuations.
2. Insufficient Amount of Fuel
A lawn mower keeps working properly when it receives a sufficient amount of power. Fuel is one of the essential sources of producing power, the other one is air. Both of them mix to provide mechanical motion that drives the motor.
When a lawn mower has an insufficient amount of fuel, it is unable to produce enough power to run the motor effectively. As a result, the engine starts surging or runs erratically. Therefore, maintaining a proper amount of fuel in the mower is essential to deliver optimal power to the engine. Thus, check the fuel level regularly.
3. Aged or Polluted Fuel
A lawn mower needs clean fuel for an efficient combustion process for powering the engine. It prevents the engine from damage, thus ensuring the smooth starting of the motor. Besides this, it prolongs the life span of the mower. On the other hand, polluted or old fuel contains pollutants like water or debris.
When this fuel is burned it forms an uneven mixture that clogs the lining of the engine with impurities. Consequently, its efficiency is reduced. This makes it difficult for lawnmowers to get power. Thus, its motor faces difficulty in starting or if it starts to run unevenly. To ensure, the lawn mower works evenly you need to use clean and high-quality fuel.
4. Malfunctioning Spark Plug
A spark plug is a small but crucial component of the combustion chamber. The engine’s ignition system is responsible for creating an electric spark. This spark ignites the fuel and air mixture to produce power. In other words, it ensures that the combustion is done smoothly.
When the spark plug becomes defective it leads to various issues of engine and performance. One of the issues is that it is difficult starting. The engine feels trouble igniting the fuel because the spark plug is damaged. Hence, it requires multiple attempts to run the engine or it won’t start at all. Therefore, it is essential to examine the spark plug and replace it if needed.
5. Loosely Connected Carburetor
A carburettor is also a part of the combustion engine of a lawn mower. Its primary function is to mix up fuel and air in appropriate ratios before they enter the combustion chamber. Moreover, it regulates the amount of power and speed of the engine. Therefore, the carburettor must be attached firmly in its place.
When it is connected loosely, it mixes up an irregular amount of fuel and air. It is because an irregular amount of air starts entering the engine. This affects the power that is being delivered to the engine. As a result, the lawn mower experiences revving up and revving down. So, check the carburettor of your lawn mower and connect it firmly.
Lawn Mower Keeps Surging? 4 Ways To Fix It
When a lawn mower surges sometimes it is normal. But when it keeps surging again and again it is abnormal for its functioning. Although it doesn’t feel wrong because the lawn mower keeps working.
However, the sound that it produces will probably make you think about why it is surging. Here are a few reasons that might cause lawn mower surging, along with the ways to fix these causes.
1. Loosely Attached Bolts
The bolts and nuts are critical parts of the engine of a lawn mower. When bolts are loose they cause extensive vibration during the operation of the mower. This causes the components to shift and misalign from their place. Moreover, loose bolts such as loose carburettor leakage of air and fuel. All these causes lead to the surging of lawnmowers.
To diagnose surging caused by loosely connected bolts, it is crucial to visually inspect the lawn mower regularly. For its proper functioning, you should tighten all the critical nuts and bolts with fasteners or drills. You can also purchase a carburettor adjusting tool kit or maintenance kit for this purpose. Hence, with proper maintenance, you can prevent the surging of the lawn mower and help it in operating safely.
2. Faulty Fuel System
A faulty fuel system can lead to surging in lawnmowers by causing insufficient delivery of fuel to the motor. It could be a clogged fuel filter that prevents the fuel from reaching the combustion chamber. As a result, an inappropriate mixture of air and fuel causes fluctuations.
On the other hand, it could be a damaged fuel pump that fails to provide enough pressure for the fuel to flow through the system. There are other causes too than address surging. These include contamination of fuel with water or impurities, leakage of the fuel line, and a faulty carburettor.
To deal with this issue you can follow the steps listed below:
- First of all, make sure the lawn mower is turned off and it is at room temperature.
- Inspect the fuel chamber to see if there is any clogged debris. If present, remove it thoroughly.
- Check the fuel line for any leakage or blockage. If necessary replace the damaged components.
- Remove the carburettor from the lawnmower and clean it using a carburettor cleaning kit.
- Next, examine the fuel filter. If it is clogged with dirt, clean it completely by following manual instructions.
3. Obstructed Carburetor
An obstructed carburettor leads to repeated speeding up and slowing down of the engine of the lawn mower. When it is clogged it disrupts the mixing of fuel with air. This causes an abruption in the engine. Moreover, if the passage of fuel in the carburettor is blocked it prevents the fuel from reaching the engine.
Besides this, it causes the lawn mower to work on either insufficient or excessive fuel which causes surging. Another cause of surging that is caused by the obstructed idle circuit of the carburettor is the struggle to maintain the idle speed
To troubleshoot the obstructed carburettor follow these steps:
Unplug the electrical plug from the socket to prevent sudden starts.
Access the carburettor by removing all the parts that cover the carburettor. For instance, a carburettor cover or air filter.
Inspect the carburettor to see if there are any blockages or debris in the fuel jets or the air path.
Use a carburettor cleaner to thoroughly remove all the dirt. If necessary put the carburetor in the cleaner for one or two hours and then clean it with a brush.
For cleaning the fuel jet and air passage use compressed air. This will blow out the debris blocking them.
Put all the components back into their places in the reverse order.
4. Defective Air Screen
An air filter is responsible for providing clean air for the mixing of fuel. If the air screen is damaged or clogged it will not provide enough air to the carburetor. As a result, the carburettor forms an uneven mixture of air and fuel. This mixture is lean because it contains less fuel. Hence, the engine starts surging as it struggles in maintaining the speed of the mower.
For regular maintenance of the air screen follow these instructions:
- To prevent any accident turn off the power to the lawn mower and wear safety gear before maintenance
- Locate the air filter using the user’s manual. It is usually located near the carburettor of the engine.
- Remove the covering of the air screen. You can use a fastener or any other tool for this purpose.
- Examine the internal area of the air filter. Check if there is any clogged dirt or debris blocking the air passage.
- Clean the air filter. If it is made of any type of fabric you can wash it with the cleaner. Otherwise, if it is a paper filter replace it with a new one.
- After cleaning make sure the air screen is dry before you place it back into its place.
- Insert the air trap back into the housing. Fasten the nuts and bolts firmly.
- Put the air filter cover back from where you removed it. After maintenance, you can check if the issue is resolved.
5 Reasons Causing Hunting and Surging in an Engine
For smooth engine functioning certain parameters need to be followed. These include getting an appropriate ratio of air and fuel, perfect sparking, and effective exhaustion. If these parameters fail to perform, the engine of the lawn mower starts surging. However, there might be some reasons too. The following are the 5 primary reasons that cause hunting and surging in the engine:
1. Hyperparameter tuning
Hyperparameter tuning is a condition in which an engine hunts and finds the optimal settings or parameters for its working. One of the common causes of surging in lawnmowers is irregular parameter tuning. When a lawn mower fails to find appropriate adjustments for smooth running the engine experiences fluctuations.
These revs up and down can be due to inappropriate speed and power. Hence, the instability caused by the irregular settings repeatedly causes the engine to perform erratically. Consequently, there is a high need for tuning to be done by choosing appropriate parameters.
2. Idle Running Problems
A lawn mower has an idle speed controller. The primary function of this control valve is to regulate the idle speed of the mower. It does this by controlling the ratio of air that passes through the throttle plate (it is a crucial component in a mower to control speed).
Hence, the working of an idle speed controller is crucial in maintaining stable idle speed. However, when it is obstructed or damaged it causes irregular and unstable engine speed. Therefore, it is necessary to clean the idle speed control valve or replace it if necessary.
3. Malfunctioning Ignition System
The ignition system of the mower ensures the smooth combustion of air and fuel in the combustion chamber. From igniting the spark to maintaining the combustion it has to perform all the tasks perfectly. A malfunctioning ignition system behaves irregularly. It either fails to ignite the spark or starts igniting the spark unevenly.
Moreover, sometimes the faulty timing of igniting spark causes abnormal behaviour. Hence, faulty ignition leads to faulty combustion ultimately causing surging of the engine. To diagnose this problem it is essential to inspect the ignition system and install new spark plugs, igniting coils, or other components.
4. Damaged Fuel Pressure Regulator
A lawn mower’s engine needs a sufficient amount of fuel to keep running. For this purpose, a fuel pressure regulator is used. It provides suitable pressure through which fuel reaches the components of the engine. If this pressure regulator is damaged the parts of the engine will not receive enough fuel.
As a result, the engine starts running at insufficient power(as the amount of air is greater than the fuel). Consequently, it leads to revving up and down of the lawn mower. Examine the lawn mower’s engine to see if the regulator needs to be replaced. However, to ensure a longer lifespan of the fuel pressure regulator keep checking the fuel pressure of the mower.
5. Broken Fuel Shut Off Valve
In a lawn mower, a fuel shut-off valve is responsible for maintaining the flow of fuel from the tank to the engine. Thus, it helps you in stopping the flow of fuel when the mover is not working. This prevents leakage of fuel and provides a sustainable storage option.
However, if the shut-off valve breaks it is unable to control the fuel flow. This results in excessive fuel functioning of the engine as the fuel is more while air is less. This functioning causes the surging of the engine. Therefore, replace the broken valve for optimal functioning.
How do you troubleshoot an engine exhibiting idle surge?
Troubleshooting an engine exhibiting idle surge involves multiple steps. It could be cleaning the clogged air screen, replacing a faulty spark plug, or cleaning an obstructed carburettor. However, there might be other things too.
For instance, ensure that there are no ignition system problems and that all idle speed control adjustments are appropriate. However, if the problem remains you should go for professional assistance. Here are the steps to troubleshoot the idle surging issue of lawn mower:
- Check the air filter if it is clogged. Remove all the debris inside it. You can soak it in a cleaner and wash it with a brush. You can also replace it if needed.
- Examine the spark plug. See if it is loose or burned out. If it is loose, attach it firmly. If it is blown, remove the old one and install the new plug.
- Clean the dirty carburettor. For this purpose, disassemble it, clean it, and make it free of residue. However, if the carburettor is defective, replace it.
- Inspect the fuel system of the mower. Check for any leaks from the fuel lines or blockage in the fuel filter. Repair the damaged components and clean the obstructed paths.
- Check the ignition system. Ensure that all the components of the ignition system are secured including the ignition coils.
- Examine the exhaust. Clear all the obstructions in the exhausting system.
- Clean the jets in the carburettor. You can use a cleaner or cleaning kit to wash it thoroughly.
Could surging be caused by spark plugs?
Spark plugs of the lawn mower might become a leading cause of surging when it becomes defective, dirty, or loose. A combustion chamber gets the current for ignition from its spark plugs via the ignition coils.
Once the air and fuel are mixed they are ignited by this ignition current received through the spark plug. This shows that it is a crucial component of the combustion chamber. But it can disrupt the working of a lawn mower when it is either faulty or blocked.
1. Blocked Spark Plugs
Blocked spark plugs contain debris that prevents them from igniting the spark at the right time. As a result, the engine of the mower starts operating on un-ignited fuel. In reality, this is the actual thing that causes surges in the engine of the mower. Follow the above-listed cleaning tips to remove debris from the plug.
2. Faulty Spark Plugs
Faulty spark plugs are unable to deliver sufficient amounts of current to generate the ignition spark. Hence a defective plug does not provide enough voltage so that the lawn mower works smoothly. Therefore, there is a high need to replace malfunctioning spark plugs to ultimately avoid the surging of the engine.
How to avoid lawn mower surging?
Every mechanical appliance suffers from depreciation. A lawn mower is also an electrical device. It can’t stay tip top all the time of its life span. No matter how much you care, it will deteriorate in the end.
However, being cautious while using it or proper maintenance can prolong its life span. The same is the case with preventing the lawn mower from surging. Here are some tips and tricks to avoid lawn mower surging:
- Perform inspection of the air filter of the engine at regular intervals. Make sure it is clean all the time you use it.
- Some parts of the lawn mower need maintenance periodically for their smooth functioning. Try to do it completely.
- Don’t use contaminated, bad quality, or aged fuel in the lawnmower. It will cause clogging in different parts of the engine.
- Before working, ensure that the fuel shut-off valve is properly in its place. Also, it should not burn out.
- The carburettor of the lawn mower should be allowing sufficient entering of clean air into the combustion chamber.
- Make sure that you clean and tighten the spark plugs and carburettor of the lawn mower every season before working.
In short, experiencing the roaring sound of a lawn mower surging in the lawn is quite frustrating. However, it is also an indication that the lawn mower has certain problems. These issues might be a blocked spark plug, clogged or loosely connected carburettor, or insufficient fuel.
However, by proper cleaning, inspecting, and maintenance you can easily fix the idle surge of the mower. This will also aid in restoring its smooth operation. Moreover, maintenance and troubleshooting of these issues not only restore its running but will also prolong the life and performance span of the lawn mower.