Learning how to clean carburetor in lawn mower is a key skill for any homeowner. A clogged carburetor is a frequent cause of lawn mower engine problems, but cleaning it can restore smooth operation. If your mower is hard to start, runs rough, or stalls out, the carburetor is likely the culprit.
This guide provides clear, step-by-step instructions. You can do this job yourself with basic tools and a little patience.
It will save you money on repair bills and get your mower running like new.
How To Clean Carburetor In Lawn Mower
Cleaning a lawn mower carburetor involves removing it, disassembling it, and using cleaner to remove varnish and debris. Safety is the first priority. Always work in a well-ventilated area and wear safety glasses to protect your eyes.
Gather your supplies before you begin. Having everything ready makes the process smoother.
Tools And Materials You Will Need
You do not need specialized mechanic’s tools for this project. Most items are probably already in your garage or can be purchased at any hardware store.
- Safety glasses and work gloves
- Basic socket set and screwdrivers (flathead and Phillips)
- Needle-nose pliers
- A carburetor cleaning spray (look for one with an extension straw)
- A small container for parts (like a muffin tin)
- Clean rags or paper towels
- A small wire brush or old toothbrush
- Compressed air (optional but very helpful)
- A new carburetor gasket kit (recommended)
Safety Precautions Before You Start
Taking a few minutes for safety prevents accidents and injuries. Never skip these steps.
- Disconnect the spark plug wire. This is the most critical step to prevent the engine from accidentally starting.
- Allow the engine to cool completely if you have just used the mower.
- Drain the gasoline from the fuel tank and the carburetor bowl. Use a siphon or tilt the mower carefully into an approved container.
- Work on a clean, flat surface with good lighting.
Step One: Removing The Carburetor
First, you need to locate and detach the carburetor from the engine. The process is similar for most walk-behind mowers.
- Locate the air filter cover on the side of the engine and remove it. Take out the air filter element.
- Underneath the air filter, you will see the carburetor. It is a metal or plastic component bolted to the engine with fuel lines and linkages attached.
- Carefully note how the throttle linkage and governor springs are connected. Taking a photo with your phone is a smart idea for reassembly.
- Use needle-nose pliers to gently disconnect the spring(s) and linkage rod.
- Pinch the clamps on the fuel line(s) and slide them back. Pull the fuel line off the carburetor nipple. Have a rag ready to catch a few drips of fuel.
- Remove the bolts that hold the carburetor to the engine. There are usually two. Keep these bolts safe.
- You can now lift the carburetor away from the engine. Be careful not to damage the gasket between the carburetor and engine.
Step Two: Disassembling The Carburetor
Now, take apart the carburetor on your work surface. Take your time to avoid damaging small, delicate parts.
- Place the carburetor on a rag. Most mower carburetors have a bowl on the bottom held on by a single bolt.
- Remove this bolt and gently pull the bowl away. If it’s stuck, tap it lightly with a screwdriver handle.
- Inside the bowl, you will find a float and a small needle valve attached to it. Carefully remove the float pin (usually a small brass pin or a screw) to release the float and needle.
- Look for the main jet, which is a brass piece with small holes, often located in the center of the carburetor body. Remove it with a screwdriver if possible.
- Some models have an emulsion tube or other small jets. Check your specific model. Lay all parts out in order on your container.
Cleaning The Carburetor Components
Thorough cleaning is the key to success. Old gasoline leaves behind a sticky varnish that clogs tiny passages.
- Spray all parts generously with carburetor cleaner. Pay special attention to the small holes in the main jet and any other jets.
- Use the extension straw that comes with the cleaner to spray into every passage and orifice in the carburetor body.
- Let the cleaner soak for several minutes to dissolve the deposits.
- Gently scrub the carburetor bowl, float, and exterior with a small brush or old toothbrush.
- Use a strand of thin wire (like from a bread tie) to carefully poke through the jet holes. Do not enlarge the holes by forcing a tool that is too big.
- If you have compressed air, blow through all the passages and holes to ensure they are completely clear. This is a very effective step.
- Wipe everything down with a clean rag. Ensure no debris or lint is left on the parts.
Inspect the float for any holes or damage. Shake it; if you hear fuel inside, it needs to be replaced. Also check the rubber tip of the needle valve for wear or a groove. The gasket on the bowl and between the carburetor and engine should be replaced if they are cracked or brittle.
Reassembling And Reinstalling The Carburetor
Reassembly is the reverse of disassembly. Work slowly and refer to your notes or photos.
- Install the new gaskets. Put the new bowl gasket in place.
- Reattach the float and needle valve, making sure the needle seats properly. Insert the float pin.
- Screw the main jet and any other jets back into the carburetor body. Do not overtighten these delicate brass parts.
- Carefully place the bowl back onto the carburetor and install the bolt. Tighten it snugly but do not strip the threads.
- Position the new carburetor-to-engine gasket on the engine.
- Hold the carburetor in place and reinstall the mounting bolts. Tighten them evenly.
- Reconnect the fuel line, ensuring it is pushed on securely. Slide the clamp back into position.
- Reattach the throttle linkage and springs. This step can be fiddly; your photo will be very helpful here.
Final Steps And Testing
You are almost done. A few final checks will ensure everything works correctly.
- Reinstall the air filter and its cover. A clean air filter is essential for proper engine operation.
- Reconnect the spark plug wire.
- Refill the fuel tank with fresh, clean gasoline. Old gas is a common cause of carburetor problems.
- Prime the carburetor if your model has a primer bulb. Press it 3-5 times.
- Set the throttle control to the start position.
- Pull the starter cord. The engine may take a few extra pulls to draw fuel into the clean carburetor.
Once the engine starts, let it run for a minute. Listen for a smooth idle. If it runs well, test it under load by engaging the blade and mowing a small area. If the mower still runs poorly, you may have missed a clogged passage or there could be another issue, like a faulty spark plug or old fuel.
How To Prevent Future Carburetor Problems
Regular maintenance prevents most carburetor clogs. A little prevention saves a lot of future cleaning.
- Use a fuel stabilizer in every tank of gas, especially if you store the mower for the off-season. This prevents gasoline from breaking down and forming varnish.
- At the end of the mowing season, either run the engine until the carburetor is completely out of fuel or use a fuel shut-off valve to drain the carburetor bowl.
- Always store your mower with a clean air filter. Replace paper filters or wash foam filters regularly.
- Never leave old gasoline in the tank for more than a month or two. Use fresh fuel.
FAQ About Lawn Mower Carburetors
Here are answers to some common questions about carburetor maintenance.
How Often Should I Clean My Lawn Mower Carburetor?
With proper fuel management and use of a stabilizer, you may only need to clean it every few years. If you notice performance issues like hard starting or rough running, it’s time to clean it.
Can I Clean A Carburetor Without Removing It?
You can try a carburetor cleaner additive in the gas tank for minor clogs. For a fully clogged carburetor, removal and thorough cleaning is usually necessary for a proper fix.
What Are The Symptoms Of A Dirty Carburetor?
The main signs include the engine refusing to start, starting but then stalling, running unevenly, losing power under load, or black smoke coming from the exhaust.
Is It Better To Clean Or Replace A Lawn Mower Carburetor?
Cleaning is almost always the first and most cost-effective option. Replacement carburetors are inexpensive and can be a good choice if the body is damaged or you want a completely new unit.
Why Does My Carburetor Keep Getting Clogged?
The most likely cause is old, degraded gasoline leaving deposits. Using untreated fuel, storing the mower with gas in the carburetor, or a dirty air filter letting in debris will also lead to repeated clogs.