How do you Clean a Lawn Mower Carburetor?

A carburetor is an important part of an engine. This is where air and fuel are mixed before being directed into the ignition chamber. Over time, grime and debris can clog fuel and air passages in a carburetor resulting in reduced performance or stalling of the engine.

At the start of the mowing season, you may discover that your lawn mower is not starting or not getting gas to the carb at all. This is usually a problem with worn-out spark plugs, contaminated fuel, or a clogged carburetor.

Signs that Lawn Mower Carburetor Needs Cleaning

Most manufacturers recommend cleaning a carburetor at least once annually. The following are signs that a carburetor needs cleaning:

1. Your lawn mower won’t start

This is the most annoying thing to happen when you have been eagerly waiting to trim your grass. Clogged air and fuel passages in a carburetor will not allow the air/fuel mixture to make its way into the ignition chamber.

2. Your engine is running rich

When your lawn mower engine is running rich, it means that there’s too much fuel in the air/fuel mixture. This is one of the main reasons why your lawn mower is smoking black.

3. Your engine is running lean

This is the opposite of when the engine is running rich. In this case, the air-to-fuel mixture is too light. A lawn mower engine will run lean when the air/fuel mixture supplied into the ignition chamber contains too little air or fuel.

This means your lawn mower will have less power as compared to a time before.

4. Constant flooding of the engine

Your lawn mower engine floods when the fuel overflows from the carburetor. In most cases, this happens when the needle valve on the carburetor doesn’t close due to dirt and debris. Your engine is flooded with fuel if your lawn mower smells gas or produces black smoke.

How to Clean a Lawn Mower Carburetor

Cleaning a lawn mower carburetor is not a complex process; you can do it yourself without hiring a professional.

Before you do anything, it is important to exercise safety. Old oil in the carburetor can be highly noxious. Work in a well-ventilated area to prevent inhaling toxic fumes. Always disconnect the spark plug cable to prevent the engine from accidentally starting.

1. Check if your lawn mower has any other problem

The first step is to ensure that you are dealing with the right problem affecting your lawn mower. You’ll want to ensure that you have the right fuel in the lawn mower, spark plugs are clean, and you have added the proper amount of engine oil.

The next thing you need to check is the air filters. A clogged or dirty air filter can also reduce your lawn mower’s performance and cause the emission of black smoke. Replace or clean your lawn mower’s air filter as recommended in the user manual.

2. Remove the outer casing and air filter

The outer casing is usually fixed on the lawn mower with screws. To remove it, simply unscrew the small bolts and nuts. The tools to use vary depending on the model of your lawn mower. Once you access the lawn mower’s innards, remove the air filter to reveal the carburetor.

3. Detach the carburetor from the engine

Remove the carburetor from the engine by unbolting the nuts that are securing it. Detach it from the fuel line by removing the throttle cables, and be ready with a rug to wipe any fuel that will spill from the system.

Now inspect your carburetor fuel and air connections for a possible blockage. If there are any corroded parts, consider replacing them since cleaning alone will not solve the problem.

4. Unbolt the carb’s bowl and clean the nut

A carburetor bowl is usually secured in place with a single nut. Before you unbolt it, clean around it using a carburetor cleaner. Now unbolt the nut, remove the bowl, and clean them appropriately using a carburetor cleaner.

In most cases, the nut has a jetted hole. Poke a paper clip or a thin wire inside to ensure the hole is free of dirt and debris. A carburetor stops working properly when this hole is clogged. Replace the bowl or nut if they are badly corroded.

5. Replace the old float needle

After removing the bowl, you can see a small pin attaching the float to the carburetor. Remove this needle and fit a new one. Also, replace the small gasket where this pin sits. Carefully do the replacements correctly to avoid troubles in the system.

6. Clean the rest of the carburetor parts

Using a carburetor cleaner, thoroughly clean all the remaining areas in the carburetor. Poke any holes in the carb to remove tiny debris and spray the cleaner to wash them away. Always use a reputable brand of carburetor cleaner that will dissolve all the grime or grease without affecting the system parts.

7. Replace the main gasket

A gasket helps in preventing leaks at varying levels of temperature and pressure. Once you are done with your carb cleaning, replace the main gasket between the bowl and the carburetor. Gaskets are usually inexpensive, and it’s worth replacing the old ones.

8. Reassemble and reattach the carb

Before you reattach the carburetor to the engine, ensure that you have reassembled all the parts and confirmed that everything is in place. Make references to your user manual or any photos you took where necessary. Finally, reattach the carburetor back to the engine, add fuel to the tank, and start the engine.

Final Thought

We have seen that a dirty carburetor can lead to several problems in your lawn mower’s engine, which can delay your mowing activities. Cleaning a carburetor is a simple process that should be part of your lawn mower maintenance. You may also seek help from a qualified dealer.

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