How do you Clean a Lawn Mower Carburetor? ( Step-by-Step Guide)

A carburetor is an important part of an engine. This is where air and fuel are mixed before directed in the ignition chamber. Overtime, grime and debris can clog fuel and air passages in a carburetor resulting to 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 could be due to various reasons including worn out spark plugs, contaminated fuel or a clogged carburetor. As part of the fix, cleaning your carburetor can bring back your lawn mower to life.

Signs a Lawn Mower Carburetor Needs Cleaning

When to clean your lawn mower carburetor majorly depends on how often you use it. It’s all about the amount of grass clippings, twigs and debris that the engine encounters. Most manufacturers recommend cleaning a carburetor at least once annually. The following are signs that a carburetor need 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. While this can be attributed to many reasons including failed spark plugs, fuel problem and bad lawn mower battery, a clogged carburetor is also a main culprit.

Clogged air and fuel passages in a carburetor will not allow the air/fuel mixture to make its way into the ignition chamber. In addition to solving any related problem, you’ll also have to clean the mower’s carburetor if you want to get back on track.

2. Your engine is running rich

When you lawn mower engine is running rich, it means that there’s too much fuel in the air/fuel mixture. This is also a reason why your lawn mower is smoking black. The huge cloud of black smoke coming from your engine is a telltale that the carburetor is not mixing fuel and air in the required proportion which leads to too much fuel burning.

3. Your engine is running lean

This is the opposite of when the engine is running rich. In this case, 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 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 is smelling gas or producing a black smoke.

How to Clean a Lawn Mower Carburetor

Cleaning a lawn mower carburetor is not a complex process and 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.

Here are the steps to follow when cleaning a lawn mower carburetor:

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 proper amount of engine oil.

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

2. Remove the outer casing and air filter

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 gain access to the lawn mower’s innards, now remove the air filter to revel 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 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 and remove the bowl and clean them appropriately using a carburetor cleaner.

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

5. Replace the old float needle

After removing the bowl, you can now 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 in the right way to avoid troubles in the system.

6. Clean the rest of 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 a carburetor cleaner that will dissolve all the grime or grease without affecting the system parts.

7. Replace the main gasket

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 one.

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 a number of problems in your lawn mower’s engine which can delay to interfere with your mowing schedule. Cleaning a carburetor is a simple process that should be part of your lawn mower maintenance. A working lawn mower is an important step of maintaining a well-manicured lawn – which is always a dream of any gardener or homeowner.

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