What Is a Lawnmower’s Choke Symbol and How to Read It?
If you’ve bought your new lawn mower, you’ll need to engage the choke when starting or running the mower. But before that, you must understand what the choke symbol entails and how engaging the choke lever affects your mower. So, what is the symbol for choke in a lawnmower?
If you find choke symbols confusing, don’t worry. This article covers you. We’ll explain a lawnmower’s choke symbol, how to read it, and more. Let’s get started.
What Is a Choke Symbol?
The choke symbol in lawnmowers shows when the choke valve is open or closed. When the choke is closed or in the “On” position, it regulates airflow into the carburetor. This controls the air entering the cylinders to mix with the fuel.
In other words, when the choke is on, it “chokes” airflow into the carburetor. This helps to start the engine, especially in cold weather. With restricted airflow, more fuel goes to the engine cylinders to provide extra heat needed to start the engine.
A lawnmower choke has a metal plate attached to the choke lever. When you engage this metal plate in the “on” position, it rotates to cover the airflow. This allows a limited amount of air into the carburetor. Restricting airflow allows a perfect mix of fuel and air that can warm up the engine.
This practice is helpful when temperatures are low. Typically, lawnmowers struggle to start when the engine is cold. The available fuel doesn’t maintain the optimum temperatures needed to start the engine.
On the other hand, an open or “Off” choke symbol allows air to flow freely. When you engage the symbol for choke off, the airflow becomes “unchoked” and flows freely into the cylinders to mix with the fuel. This happens when the engine has been warmed up enough to be operated.
How To Read Choke Symbols
You now know what the symbol for choke in lawnmowers means. But how can you tell what each symbol indicates?
Before we answer this question, it’s worth noting that mower models can have varying choke symbols. So, it’s necessary to understand what choke symbols in your mower indicate. Below we look into different choke symbols and what they mean.
An “O” Symbol With a Line
Some mowers have a horizontal or diagonal and vertical line running across the “O” symbol. An “O” symbol with a horizontal or diagonal line in the center indicates the choke is in the “On” position. Pull the choke lever up or forward to point to the choke closed symbol.
On the other hand, an “O” symbol with a vertical line in the center indicates the choke is in the “Off” position. You can pull the choke lever down or backward to point to the symbol for choke open.
A Rabbit and a Turtle Pair
This is another common symbol for choke you’ll find in lawnmowers. The rabbit symbol indicates the choke is open to allow airflow. This means the engine is ready for operations.
The turtle symbol indicates the choke is closed to regulate airflow. This allows for a steady flow of fuel into the engine to allow it to start.
“I” and “O” Choke Symbol
Some mowers feature “I” and “O” choke symbols with a red or blue switch. These symbols appear on the alternate sides of the red or blue switch.
The “I” position indicates the choke is on or closed to restrict airflow. You can press the switch to the “I” position to start the engine when the temperatures are low.
The “O” position means the choke is off or open to allow air to flow freely. Press the switch to the “O” position when the engine has warmed up and is ready to be operated.
- Open/Close: The “Open” label means the choke is off, while the “Close” label indicates the choke is on.
- On/Off: The “On” label indicates a closed choke, while the “Off” label means the choke is open.
- Start/Closed: The “Start” label means the choke is on, while the “Closed” label indicates the choke is off.
- Full Choke/Run: A “Full Choke” label indicates the choke is on or closed to allow air to flow. Sometimes, “Full Choke” can be labeled as “Choke.” The word “Run” indicates the choke is off or open.
Mowers with twin-cylinder engines might have a “Half Choke” label between the “Full Choke” and “Run” labels. The “Half Choke” indicates the choke is halfway opened or closed. This choke control prevents the mower from dying out when switching from the “Run” to the “Full Choke” position.
You’ll need to switch to the “Half Choke” position to allow the mower to adjust to the restricted airflow. Once the engine adjusts, you can switch the lever to “Full Choke” without causing the engine to knock off.
What if your mower doesn’t feature the “Half Choke” label? Set the choke lever between the “Full Choke” and “Run” positions to prevent your mower from dying out. Once the lever is in the middle, your mower will adjust to the reduced airflow.
If understanding the symbol for choke sounds confusing, refer to the owner’s manual. You’re sure to find information about the meaning of each choke symbol and the ideal position to move the choke lever when starting or operating the mower.
Location of the Choke on Lawn Mowers
The position of the choke varies from one lawnmower to another. This is especially true for different models or mowers from different manufacturers. However, most mowers have a choke valve located on the engine body. Others have a choke lever positioned on the mower’s handle.
With time, you’ll find it challenging to locate the choke on your lawn mower when it gets covered by dirt and debris. Thankfully, some mowers feature a bulb on the choke symbols. If the bulb malfunctions, you won’t be able to tell whether the choke is in the on or off position.
If your lawnmower features a butterfly valve, you’ll find the choke in the manifold.
When locating the lawnmower choke, it’s necessary to consider whether you have a manual or automatic choke. You can locate a manual choke by following the cable linking the trigger to the engine. For an automatic choke, find it near the air intake, just next to the carburetor.
Can You Operate a Lawnmower With the Choke On?
It’s wrong to run your lawnmower when the choke is on. The choke is helpful when starting your mower to optimize fuel combustion. Switching the choke to the “On” position creates a low air-fuel ratio, producing a rich fuel mixture.
When the fuel runs rich, it contains less air and gets easy to heat up. Heating fuel to operating temperatures provides the required power to start the engine.
If you open the choke when starting the engine, you may experience various starting problems. Allowing too much air into the carburetor and combustion chamber cools down the engine. If you try to start the engine, it may sputter, stall or shut down.
The goal is to ensure the combustion engine receives the right amount of air. To achieve this, understand when to turn the lever to match the correct symbol for choke.
Once the engine starts, open the choke to allow a steady airflow. Doing this creates a high air-fuel ratio known as a lean mixture. Your lawnmower engine requires lean fuel to keep running smoothly. This is a great way to use fuel economically, maintain the engine in top condition and reduce pollution.
When Should You Run the Lawnmower With the Choke On?
After starting the engine, you may opt to run your mower when the choke is on due to the following reasons:
- When there’s a blockage in the fuel line or fuel filter – Blockage can prevent enough fuel from reaching the carburetor.
- When the octane mixture in the fuel is less than optimal – This usually happens if there’s water or additives in the fuel.
Fix these issues first before operating your mower. You can do this by unblocking the fuel line and replacing the filter. If the culprit is the fuel mixture, drain it and add fresh fuel.
Should You Leave the Choke on During Storage?
When storing your mower, turn the choke to the “Off” position. When warming the engine for start-up, you only need to move the choke lever to the “On” position.
Turning the choke lever to the “Off” position makes your work easier the next time you want to operate your mower. You don’t have to refer to the manual to know if the choke is opened or closed.
If you want to start the engine, especially when the weather is cold, you only need to switch the choke lever to the “On” position.
Wrapping Up
When using a lawnmower, it’s advisable to understand the symbol for choke to ensure smooth operations. Choke symbols vary from machine to machine.
A closed symbol indicates the choke is on to regulate airflow into the carburetor and combustion chamber. This practice is beneficial when turning the engine on.
An opened symbol indicates the choke is off to allow air to flow freely. After warming up the engine, you can turn off the choke to run your mower.
Hello! My name is Chris, and I am the founder of Yard Floor. When I was a toddler, my family had a lush green lawn. I was at the center of caring for and maintaining this lawn and even proceeded to take an associate’s Degree in landscaping. I am here to share my years of experience with you – be it repairing your mower/tractor or caring for your lawn.
Honda Autochoke Service Bulletin
Looking to find the service bulletin (January 2014) in referrence to the automatic choke issue.
Called Honda who told me to call a dealer. The dealer told me to call Honda. So the circle begins.
Anyway, trying to find out any important information about the issue, like what to look for and what parts should be replaced.
This mower is out of warranty, so it is on me.
Tried to contact [email protected] but he must be away on vacation.
tabora
Looking to find the service bulletin (January 2014) in reference to the automatic choke issue. Called Honda who told me to call a dealer. The dealer told me to call Honda. So the circle begins.
From research, I can tell you that Model # HRR2168VYA S/N = MZCG8501313 was in a batch of units that may have had a defective Autochoke device. If you are close to that number, yours may also be affected. Dealers have access to all the Service Bulletins. There should be no finger-pointing.
FYI, Robert is out of the office for an undetermined period and is currently unavailable to respond. On the snowblower forum we’ve been told:
A final note: [email protected] is not available to respond to forum inquiries at this time. We hope he will be back online soon. If you have questions for Honda, please reach out to our Customer Relations team directly. You can contact us here: https://powerequipment.Honda.com/support/contact-us
“Keep thine ears on the engine and thine eyes on the tach and dipstick, lest thy whirlybits seek communion with the sun.”
tabora
Did a little more digging. I’ve attached what I believe may be the Canada version of the Autochoke Service Bulletin.
Here is info from [email protected] on another forum regarding Service Bulletin #98:
Honda HRR216K8VKA, PKA Service Bulletin: Engine Won’t Restart
Honda has released a Service Bulletin for the HRR216VKA and PKA mowers to resolve a “Engine Won’t Restart” issue.
ONLY mowers within the following range are affected: MZCG-8400001~MZCG-8669999.
The symptom is an engine that may not restart after being shut off before the engine has been fully warmed up. Often this happens when a cold engine is only run for a minute or two, stopped, then a restart is attempted. The issue is the choke plate remains fully closed because the AutoChoke’s thermowax cylinder senses the engine is still cold.
The fix is replace the thermowax cylinder, insuring it makes full contact with the engine, and replace the AutoChoke control assembly if it is binding or not working correctly. There’s also a small bracket that can help regulate temperature that may be installed.
If you have a mower in the affected range, and it has this problem, and is still under warranty, Honda will typically pay for the repairs. Delivery and pick-up of the mower to and from a Honda dealer is not included. You can find a dealer in your area at this link:
Ask about Honda Lawnmower Service Bulletin #98, if your dealer isn’t aware of it yet.
Here is a link to a video showing how to service the autochoke yourself:
How To Start A Toro Lawn Mower With A Choke [Step By Step Guide]
It can be intimidating to start a Toro lawn mower for the first time. Now, say you’re in front of the machine but don’t know how to start it with a choke. We researched this concern for your convenience, and here’s what we found!
The steps to starting a Toro lawn mower with a choke often depend on which model is in your possession. In particular, Toro push mowers often have different starting procedures than the brand’s riding mowers.
So continue reading as we tackle these startup procedures in greater detail. We’ll also talk about other relevant yet still essential pieces of information, such as the possible reasons why your lawn mower doesn’t start. With that said, let’s dive right in!
How Do I Start My Toro Lawn Mower?
Before you start your Toro lawn mower, you should practice proper preparation procedures to ensure the machine works properly. Some of the things you need to do are:
- Replace the air filter. A dirty filter can prevent the lawn mower’s engine from working optimally.
- Change the oil. An unlubricated Toro lawn mower might become prone to different problems, especially its moving parts.
- Inspect and replace the spark plug if necessary. Carbon buildup can prevent the spark plug from providing the required energy to the mower’s motor.
- Flush out the old fuel. Then, replace it with a fresh batch to prevent harm to the machine’s engine.
- Apply a fuel stabilizer. This product can help extend the lifespan of the fuel in the lawn mower, particularly if you’re not going to use the machine frequently.
After completing these, here are the steps to start your push and riding Toro lawn mowers with chokes:
Starting A Toro Push Lawn Mower
- Press the primer button thrice
- Pull and hold the safety bar
- Maintain a good hold on the safety bar while pulling the starter rope
- Repeat steps 1 to 3 once or twice if needed
Note: Many new Toro push lawn mowers, such as the Recycler 22, don’t have a choke lever. Instead, these models have an auto-choke feature that does the clutching for their users automatically.
Starting A Toro Push Mower
- Place the push mower’s ignition key into the ignition slot
- Turn off the Power Take-Off (PTO) switch or clutch
- Engage the parking brake
- Place the choke lever into its full position
- Turn the ignition key and hold it in its turned position for not more than 10 seconds.
- Allow the engine to warm up for about 30 seconds
- Set the choke lever to its half position
- Wait another 30 seconds before setting the choke lever to its off position
Some Toro lawn mower models may require you to complete additional steps before using them. So consult your owner’s manual to verify these additional procedures.
Why Won’t My Toro Lawn Mower Start?
If the steps mentioned above didn’t work, perhaps your Toro lawn mower encountered an issue that prevented it from starting.
Defective Start/Ignition Switch
Physical harm to the start or ignition switch may cause it to fail. Without this switch, users may not be able to start their Toro lawn mowers without applying workarounds.
Broken Recoil Spring
The recoil spring is typically attached to the lawn mower’s pull cord. Pulling this spring should also spin the crankshaft and flywheel to start the machine.
But a broken recoil spring prevents the mower’s motor from turning over.
Faulty Spark Plug
As mentioned earlier, carbon deposits may accumulate in the spark plug. Failure to remove the substance buildup may lead to cracks in the component’s porcelain insulator.
The result may be that the spark plug fails to provide the recommended energy to start the mower’s engine.
Clogged Carburetor
The carburetor is an essential component in many gas-powered lawn mowers, including those from Toro. It’s responsible for controlling the flow of the air-fuel mixture in the machine’s engine.
But a blockage may occur in the carburetor. If so, the clog may make it difficult for other lawn mower parts to receive the necessary air and fuel.
Bad Fuel Pump
As its name implies, the fuel pump pushes the necessary fuel into the engine. However, this assembly may fail, resulting in the engine’s under or over-filling fuel.
Stop attempting to start the Toro lawn mower immediately if you suspect the fuel pump to be at fault. Continued use may result in serious harm to the machine.
At this point, you may also find it interesting to learn about the type of gas Toro mowers use. You can read our post on that topic to help you choose the correct fuel for these machines.
How Do You Fix A Toro Lawn Mower That Won’t Start?
First, troubleshoot your Toro lawn mower. Doing so should allow you to find out why it’s not starting. Once found, you can use the appropriate solution to restore the machine’s engine’s normal functions.
Here are some possible solutions that may help you in repairing your Toro lawn mower:
Replace The Air Vane Spring
Air vane springs are usually in many push mowers on the market. Many Toro lawn mowers have these components since they are part of the machines’ auto-choke systems.
Here are the steps to help you replace the air vane spring:
Step-By-Step Guide
- Loosen the screws securing the lawn mower’s top cover.
- Remove the top cover and set it aside temporarily.
- Grab the old spring with the needlenose pliers and remove it from the machine.
- Install the new spring in the same location as the old unit.
- Reinstall the top cover.
- Turn on the Toro lawn mower to check if it works as intended.
Note: Only install an air vane spring compatible with your Toro lawn mower model. Installing an incompatible spring may stall or prevent the engine from starting.
You can also watch the video if you need a visual guide:
Replace The Spark Plug
Replacing the spark plug in a Toro lawn mower is a reasonably straightforward task. Generally, you only need to follow these steps to complete the replacement:
Step-By-Step Guide
- Disconnect the line connected to the old spark plug.
- Remove the old spark plug with the spark plug wrench.
- Install the new spark plug to the same terminal as the old unit.
- Attach the line you removed earlier to the new spark plug.
- Try turning on your lawn mower to check if it works properly.
Watch this short clip if you need a visual reference for the steps mentioned above:
What Are Alternatives To Toro Lawn Mowers?
You might consider replacing your old Toro lawn mower with a new unit. So here are some excellent candidates that might pique your interest:
EGO Power LM2135SP Self-Propelled Lawn Mower
This lawn mower runs on battery power instead of gas. That means it has fewer harmful emissions than models running on fuel.
Toro TimeMaster Push Mower
Take a look at this push lawn mower if you want to stick to the Toro brand. This self-propelled model adjusts to your walking pace for comfortable and convenient mowing.
It also has a blade stop safety feature that automatically activates if the machine detects direct contact with foreign objects like your skin.
Final Thoughts
Starting a Toro lawn mower with a choke often requires you to follow specific steps. So follow the procedures highlighted in this post. If done correctly, you should be able to use the machine properly.
Troubleshoot and repair your Toro mower if its engine doesn’t turn over after following the correct startup process.
Made it to the end? Check out these helpful related articles below!
Briggs Stratton Automatic Choking Technology Moves to Riding Mowers
April 17, 2014 — Briggs Stratton launched the ReadyStart feature for walk-behind mowers in 2005, and has now developed the technology for use in riding lawn mowers.
| Consumers want to know that their mower is going start with minimal effort each and every time. ReadyStart takes the guesswork out of starting the engine and Briggs Stratton is the only manufacturer to bring this system to riding mowers designed for residential use. |
The feature is launching in some Husqvarna riding mower models. The system is part of Briggs Stratton’s new V-Twin engines. The system is mechanically driven and adds two major components to a traditional engine platform: a nylon air vane and a temperature sensitive bimetallic thermostat.
The system provides a significant user benefit: starting is made easier because there is no need to prime or choke the engine.
The ReadyStart automatic choking feature is designed to start the engine within two 5-second cranking attempts in weather above 32 degrees F. The system automatically senses engine temperature to deliver the right amount of fuel to the carburetor.
“Consumers want to know that their mower is going start with minimal effort each and every time,” says Carissa Gingras, marketing director for consumer engines and service at Briggs Stratton. “A no-choke starting system, ReadyStart takes the guesswork out of starting the engine and we are the only manufacturer to bring this system to riding mowers designed for residential use.”
Featured on Briggs Stratton’s V-Twin engines, the ReadyStart feature is mechanically driven and adds two major components to a traditional engine platform: a nylon air vane and a temperature sensitive bimetallic thermostat.
Available for purchase through Husqvarna dealers, the following riding mowers feature the ReadyStart System:
- YTH24V48 (Husqvarna FastTractor)
- YTH24V46
- SmartSwitch Tractors. GT48XLSi and GT52XLSi
- SmartSwitch Zero Turn Mowers. RZ46i and RZ54i
Engines equipped with the ReadyStart system are made in the U.S.
Q: I can’t seem to figure out why my lawn mower won’t stay running. There’s plenty of gas and oil in it. Can it be repaired, or is it a lost cause?
A: Lawn mowers seem like simple machines, yet they require some TLC to operate smoothly—especially if they’ve been sitting in the shed for a while. A full gas tank and oil reservoir are the essential first steps when checking why the lawn mower won’t stay running, but the problem could also be a dirty filter, clogged carburetor, improper fuel mixture, or a dirty spark plug. If you’re ready to get your hands dirty, check out these troubleshooting tips to get your lawn mower running again. However, you may need a lawn mower specialist to get you back to trimming your grass. Alternatively, a landscaping professional can take care of it for you.
The fuel might be old and dirty and needs to be replaced.
Fuel that has sat in the motor for a while can evaporate and leave a sticky residue. The inlet and outlet ports leading to the carburetor could be clogged, as well as the fuel filter. In cold, wet winter seasons, condensation can collect inside the tank, which doesn’t mix with the fuel. Replace old, dirty, or diluted fuel; adding fresh fuel to it won’t solve the problem. Drain the old fuel out of the tank and collect it to be disposed of safely per local requirements. Clean off the carburetor ports before refilling the tank.
The air filter might be dirty, which prevents it from getting enough air.
Motors have air filters to collect and trap dust and debris that could clog the machine’s inner workings. Over time, they become clogged and need to be replaced. If an air filter isn’t working correctly, the motor can’t get enough air to prevent overheating. Inspect the air filter for carbon deposits or oil, and replace it if it’s contaminated. Paper filters always need immediate replacement if they’re contaminated, but a dusty foam filter could benefit from being washed and dried at least once before replacement. It’s recommended to replace the air filter after every 25 hours of use.
The carburetor might be clogged and dirty.
One inconvenient reason a lawn mower won’t stay running is a problem with the carburetor, which mixes the air and fuel for internal combustion. The carburetor bowl may be clogged, or the inlet and outlet ports are slimy from fuel residue. Remove them and spray them with an aerosolized carburetor cleaner (not water). You can try disconnecting the fuel lines and spraying them out with cleaner to remove any sitting sludge as well. Replacing the fuel filter is also recommended if the carburetor is showing signs of contamination. If the lawn mower has a gas cap vent, open it to clear any visible clogs. If none of these steps solve the problem, it’s worth having the carburetor replaced by a pro.
What is an Automatic Choke?
An automatic choke is a device that is mounted on the carburetor of a gasoline engine. When the ignition key is turned to the start position, this device is activated and the engine receives a much richer fuel mixture allowing the engine to start more easily. Once the engine has reached operating temperature, the choke is deactivated and the engine operates without the aid of a choke.
The carburetor mixes air and fuel and distributes this mixture to the engine. The engine then ignites this mixture and power is made. In cold weather, the engine requires more fuel than air to start properly. The choke mechanism blocks some of the incoming air from entering the carburetor. As the engine warms up, it is able to operate with more air and less fuel, so the choke is no longer needed.
Early gasoline engines used a manual choke mechanism. This manual choke was operated by pulling a knob in the operator’s compartment. Once the engine was started, the operator pushed the knob in and the choke was eliminated. The automatic choke uses the vehicle’s battery power to engage and disengage itself. This helps to eliminate the problem of leaving the choke on, which leads to poor fuel mileage.
The automatic choke is found only on carbureted gasoline engines. Fuel injected engines do not utilize a choke system to aid cold weather starts. Much like an automatic choke, a fuel infection system sprays more fuel into the combustion chamber at the time of start up. This allows the engine to run much richer and aid in cold weather starts.
Maintenance of the automatic choke is relatively simple. A bit of silicone spray on the choke plate shaft and spring at oil-change intervals will keep the automatic choke functioning properly. Dirt and debris can be removed from the choke unit with compressed air or a can of carburetor cleaner.
A common problem with automatic choke mechanisms is the failure to disengage when the engine warms up. This problem is easily rectified by a carburetor repair specialist. In most cases, a simple adjustment is all that is required to return the choke to proper working order. In some extreme cases, the choke mechanism must be replaced to ensure proper operation.
Have a competent mechanic service the choke at least once a year to prevent problems. Refer to the vehicle’s operator’s manual for proper operating instruction, as well as proper cold weather starting techniques.