Ever wondered what a choke actually does and whether you should run with the choke open or closed? In this guide, we’ll present comprehensive choke symbol basics for mower beginners to start and run their engines smoothly.
What Is A Choke & How the Choke Works
The choke is a valve used on small engine equipment like mowers. It performs the function of adjusting the air supply to the engine. When you close the choke, it restricts airflow, which creates a richer fuel mixture (more fuel, less air). This is exactly what a cold engine needs to start. Once the engine warms up, you open the choke to allow normal airflow for regular operation.
How to Read the Choke Symbol
What Does the Choke Symbol Look Like
On most lawn mowers, you can see a small plate or butterfly shape between two lines. Some mowers use the word “Choke” or “Start” instead. The table below can help you recognize the choke symbols.
| Choke Symbol Type | Symbol Description |
|---|---|
| Choke On Symbol | Horizontal (—) or diagonal ( / ) line, or the words ‘Choke’, ‘Full Choke’, or ‘Start’ |
| Choke Off Symbol | Vertical line ( | ) or the word ‘Run’ |
Note: Always check your owner’s manual for your specific symbol.
Where to Find the Choke Symbol on Your Lawn Mower
On your lawn mower, you can find the choke symbol and choke lever in several places.
Common Locations for Choke Symbol & Lever
- Near the engine
- On the control panel
- Right next to the throttle
Look for a small lever with a symbol or the word ‘choke’ printed nearby. The choke lever usually moves back and forth or up and down. You might notice a small tab or plate that you can push or pull. If you can’t find the choke level, you can check the area around your air filter or carburetor. Many manufacturers put the choke lever close to these places for easy access.
Note: If you have trouble finding the choke lever, look up the pictures or diagrams in your owner’s manual.
Choke Controls on Newer Mower Models
Newer lawnmowers use different controls for the choke lever. Some models use a combined throttle and choke lever. You move one lever to start and run the engine. For other mowers, they use a push-button or a dial rather than a traditional lever. The function remains the same, though. You can still use the choke lever or control to adjust the fuel-air mixture for starting. For some electric star mowers, the choke lever might be hidden into the starting system. You can always look for the choke symbol or a label near the controls. If you see a lever, button or dial with a symbol, it’s likely your choke lever. Whatever type of choke lever your mower uses, you use it to start and run your engine smoothly.
Choke Open vs Closed Symbol
If you have ever asked yourself, “Should I run with the choke open or closed?”, you’re not alone. The answer depends on one simple thing – whether your engine is warm or cold.
Choke Closed (On) Position for Cold Engine
When the choke lever is in the closed or on position, the choke plate blocks most of the airflow into the carburetor. This gives your engine a rich fuel mixture — more fuel, less air. A cold engine needs this extra fuel to fire up because the fuel does not vaporize as easily at low temperatures. You will usually see a horizontal line (—), a diagonal line (/), or the words “Choke” or “Full Choke” next to this position on your mower.
Choke Open (Off) Position for Normal Operation
When the choke lever is in the open or off position, the choke plate moves out of the way and allows normal airflow into the carburetor. Your engine gets the right fuel-to-air ratio for smooth, steady operation. Once your engine warms up, it no longer needs a rich mixture. You will usually see a vertical line ( | ) or the word “Run” next to this position on your mower.
How to Use Choke Step by Step
Start with Choke
Starting your lawn mower with the choke on ensures your engine get the right fuel-to-air ratio for a cold start. Here are several steps for you to follow to make sure your mower stars smoothly.
- Find the throttle lever on your mower (near the seat or on the left side of the engine).
- Move the throttle lever to the choke on position (usually marked with a choke symbol or labeled as full choke)
- Make sure the engine is off before you start
- Check the area around the mower to be clear
- Pull the starter cord or press the start button
- Make sure your separate choke switch is set to choke on before you start
Note: Always use full choke when starting a cold engine. This ensures the fuel-to-air ratio is rich enough for easy ignition.
Switch to Run
After your engine starts, you need to switch from the choke on to the run position. It is crucial to keep your mower running smoothly. Once the engine warms up, you should try the following steps.
- Let the engine run for 30 seconds or so with choke on. Beware of weird sound
- Move the throttle lever away from full choke and slide it to run or choke off position
- The fuel-to-air ratio comes back to normal and your mower gets the right mix for mowing
- Move the lever back to choke on for seconds and then try switching to run if your engine sputters or stalls
Note: Don’t leave the choke on after the engine warms up. It may cause poor performance. Always switch to run once the engine sounds smooth.
Choke Troubleshooting
Choke Left On
What will happen if you leave the choke on after the engine starts? You’re likely to notice the following problems.
- The engine runs rough or loses power
- Black smoke from the exhaust
- Engine overheating or even stalling
- Fuel waste and a damaged spark plug
- The carburetor gets dirty faster and potential starting issues in the future
These are common consequences of improper use of a choke. To fix it, you can let the engine cool down, move the choke to off, restart the engine and listen for a steady sound. If the problems continue, check and clean the carburetor as part of your regular maintenance. Look up for How to Clean Your Carburetor Step by Step.
Note: If your engine runs poorly or smells like gasoline, move the choke lever to the off position immediately.
Choke Off Issues
If you try to start your engine with the choke off, you may face cold start difficulties, especially in cold weather. The engine may not start or you may need to pull the cord many times. It is often the case that the thermowax actuator (Honda models) does not close the choke butterfly valve, causing the carburetor to give too much air and not enough fuel. To fix it, you can always use a choke for a cold start. If the engine won’t start, check the carburetor to make sure it is not dirty or blocked. Then, clean the carburetor and inspect the valves and seals. Below are tips to prevent these problems.
- Inspect seals & valves for wear
- Clean filters and remove buildup in the carburetor
- Check for rust or corrosion
- Lubricate moving parts
Note: Good maintenance keeps your choke and carburettor working well. This helps your engine start easily and run smoothly.
FAQs for Choke Symbols
Can you leave the choke on?
No, you should not leave the choke on for an extended period. Leaving it too long can cause engine rough running & overheating, excessive fuel consumption and spark plug fouling. Always switch the choke off once the engine warms up.
How long should I leave the choke on after starting?
Let your engine run with the choke on for about 30 seconds. Listen for a smooth sound. Once the engine warms up, move the lever to the run position.
Do all lawn mowers have a choke lever?
Not all mowers have a visible choke lever. Some new models use automatic or built-in choke systems. If you do not see a lever, check your manual for details.
Can I start my mower without using the choke?
You can have a try. But most engines need the choke for a cold start. Your mower may not start or take many pulls without the choke.
Which symbol is choke on?
The choke is on when the lever is directed to a horizontal or angled line. At that time, the choke valve will restrict airflow into your lawnmower’s engine.
How do I know if my choke is working properly?
If your engine struggles to start or run smoothly in cold conditions, the choke may not close properly. If your engine runs smoothly when cold but starts to run rough or stall as it warms up, the choke may not open properly. Both cases require professional inspections.
Final Words
Learning how to read choke symbols and use the choke properly is a simple way to keep your mower running smoothly season after season. Always start with choke on for a cold engine, then switch to the run position once it warms up. This small habit protects your engine and save your from unnecessary repairs. That said, even with proper choke use, some critical parts wear out over time. A dirty carburetor, a fouled spark plug, or a worn choke lever can all cause the same frustrating problems, such as rough starting, stalling and poor performance. At FridayParts, we carry a wide range of replacement parts for lawn mowers and small engine equipment, including carburetors, spark plugs, air filters, choke levers and cables at an affordable price. Whether you’re doing routine maintenance or fixing a persistent starting issue, we’ve got the parts to get your mower back to its peak performance.
