How To Clean A Lawn Mower Carburetor


Machines like lawnmowers have variable usage depending on the season. During the winter season, they are not used at all, and less during early spring and late autumn. This means they spend quite some time idle. Before starting the new season, you must check if it needs cleaning, especially the device’s core: the carburetor.

If yes, you can use our systematic guide to cleaning a lawn mower carburetor. A smudged or clogged carburetor can become a quotidian cause for a mower to stop operating smoothly. Realizing the significance of this cleaning can prevent you from the plausible problems caused by the blocked carburetor.

Cleaning of the carburetor is not as complicated as it may seem. People generally opt to take it to the repair shop, but this is something you can do yourself easily. If you want to save yourself some cash, have a look at this article. We have put together all the critical steps for the preventative maintenance of a lawnmower carburetor.

How To Clean A Lawn Mower Carburetor:

  • Step 1. Safety Precautions
  • Step 2. Remove the outer casing of the engine
  • Step 3. Remove the air filter housing
  • Step 4. Unbolt the carburetor and remove it from the fuel line
  • Step 5. Unbolt the bowl and clean the nut
  • Step 6. Clean the main gasket
  • Step 7. Replace The Needle
  • Step 8. Check the Connections
  • Step 9. Utilize Carburetor Cleaner
  • Step 10. Reassemble and reattach

The effects of clogged carburetor:

Before you resort to cleaning the malfunctioned carburetor, you must be aware of its harmful effects.

  • Trouble starting: The lawnmower engine has trouble starting.
  • Stalls: The engine starts but stalls while you are cutting the lawn grass.
  • Runs rough: The engine runs rough during mowing.
  • Black smoke: Black smoke keeps on spilling from the exhaust.
  • Increase fuel consumption: There is a discernible increase in fuel consumption during everyday lawn mower use.

General Step-By-Step Guide:

The steps mentioned above will undoubtedly help you get familiar with mechanical components and save your time and cash. Do not worry, as we promised; we would discuss every step individually.

● Step 1. Safety first:

Before you start, make sure the mower engine has cooled. Safety should always be your primary concern whenever carrying out repair work of any kind. Due to old or rusty fuel, the remnant in the fuel tank can be highly noxious. The most important thing is to ensure that you are working in a well-ventilated area when taking apart a carburetor. If you are working in a garage, open the door and any windows. It is recommended to use a ventilation fan in such areas. If your garage or workshop does not have windows or doors you can open, you should consider working somewhere to avoid personal injury or property damage.

● Step 2. Remove the outer casing of the engine:

If it is your first time cleaning the carburetor, there is an important tip; it is suggested that you record a video during this procedure or take some photos of the assembly after every step so that you can assemble each part back onto its original place. It highly depends on your Lawnmower model; generally, it detaches the outer paneling to reveal the Lawn mower’s innards that are done by unscrewing a few screws.

● Step 3. Remove the air filter housing:

Primarily, remove the screw holding on the air filter, then all screws holding on the carburetor, and finally pull the housing off; by doing this, the carburetor becomes visible. Now detach the breather tube. For cleaning the carburetor, the principal thing is to make sure that the air filter is free of twigs, dirty grass, and debris. A clogged or blocked air filter will create black smoke that can be seen coming out of the muffler. It will block the air passage for our carburetor, and thus it cannot “breathe” due to hindrance.

● Step 4. Unbolt the carburetor and remove it from the fuel line:

Slide the carburetor off the mounting bolts, carefully disconnect the fuel lines and remove the main assembly component. Please remain cautious while drawing the fuel lines as fuel spilling might occur. It is recommended to have some rags ready to catch the liquid because some fuel would spill out of both the carburetor and the fuel line. Fuel spilling ensures that your fuel line is clear and hence no fuel blockage is there. If no spilling occurs, it may mean you have clogged fuel lines, and you need to check that.

Step 5. Unbolt the bowl and clean the nut:

Initially, clean around the carburetor bowl with carburetor cleaner or spray. A single screw clutches the bowl; unthread that screw to release the carburetor bowl. This nut is a jet with a hole, and you need to make sure that the gap is clear of any barriers. This can be done simply by poking a paper clip or piece of wire inside. Debris inside the jet is one of the most frequent reasons for a carburetor to stop working, and merely cleaning out the hole could fix your problem. In the end, spray some carburetor cleaner on the nut. Also, if the bowl is impaired or predominantly dirty, you should replace it rather than clean it.

● Step 6. Clean the main gasket:

You need to unthread the screws to release the prime bulb and base, remove a metering plate, diaphragm, and the main gasket that goes between the carburetor and the bowl, so the fully disassembled carburetor is here. If the gasket is old or rusted, clean it by scraping it off with sandpaper because this rust might affect the bowl’s functionality. If the gasket is completely damaged, remove the old one and fit a new one in its place.

Step 7. Replace The Needle:

Once you remove the bowl, you will see the float attached to the carburetor with a pin. Remove the float pin to release the float and the needle. Inside the carburetor, you will see a small gasket where the hand sits; you should also replace this, taking care to fit the new one the right way around.

● Step 8. Check the Connections:

After all the things mentioned above, if the problem persists, we need to check all the possible connections between choke plates and the carburetor’s throttle, as these things get messy when they become dirty and can bind and stick to each other. Furthermore, perpetual vibration and abrasion can detach screws every passing day, contributing to abnormal handling and auxiliary carburetor issues.

● Step 9. Utilize Carburetor Cleaner:

With all the grass, twigs, and debris, the hour’s need is to use a carburetor cleaner to clear out all the deposits within the carburetor. These deposits can congest the air and fuel passage to decrease efficiency, thus stopping the engine altogether. Fortunately, you do not need to take the carburetor out of the machine to perform this operation.

We can use any merchandising carburetor cleaner for lawn mower, like WD-40, which consists of a simple spray can with the exposed carburetor intake and outlet ports, spray it into the ports to clean out any residue, and you are done with cleaning of the inside holes and outside of the carb as well. Make sure that all the holes are clear and free of debris.

After cleaning the carburetor’s transparent surfaces with this cleaner, you must check any other maintenance problems, like old fuel, filthy air filters, old and fouled spark plugs, deteriorated engine oil, and more.

● Step 10. Reassemble and reattach:

Here are some steps to follow to reinstall your carburetor:

  • Step 1. Dry the carburetor: Initially, allow the carburetor to dry and then reassemble it, ensuring that you properly position the diaphragms, gaskets, metering plate, and primer base as required along with the float needle and float.
  • Step 2. Arrange the bowl: Ensure the bowl gasket is adequately arranged and reposition the bowl if necessary.
  • Step 3. Reassemble the carburetor: Move the restored carburetor smoothly back onto the mounting bolts and fasten the throttle coupling to the throttle lever.
  • Step 4. Reattach the fuel housing: Reattach the fuel line to the carburetor.
  • Step 5. Assemble the air filters: Relocate the air filter casing together with the air filter and filter cover.
  • Step 6. Reinstall the outer casing: Reinstall the engine cover if necessary.

After inspecting and cleaning the lawn mower thoroughly, everything is back in place, adding fuel to the tank and starting it up. If you have cleaned the carburetor perfectly and left no technical fault, it would now definitely start up easily and quickly.

Additional Precautionary Measures:

Here the question arises whether this cleaning is enough.

If cleaning the carburetor is not fruitful, reconstruct or substitute the entire carburetor and take some preventive measures for future use.

  • Fresh Fuel: Always use new fuel to avoid significant problems regarding stalling. Do not keep the power for an extended period in the cabin.
  • Fuel stabilizers: Use fuel stabilizers to avoid the residual formation in the compartment, as it comprises chemical additives that enhance the residual fuel life.
  • Carburetor repair kit: Carburetor Cleaners are readily available in the market, acting as anti-rust agents and cleaning the grease. It helps you in servicing and replacing the defective components like the float and float needle, gaskets, and diaphragms. If the carburetor still performs poorly, you may need to replace the old carburetor with a new one.  

Besides cleaning a carburetor, be aware that a dirty air filter or a clogged fuel filter can also cause a lawnmower engine to stall or run rough. As part of your annual lawn mower maintenance, you should always replace the air filter and fuel filter with new ones.

Frequently Asked Questions:

1. Can we clean a carburetor without removing it?

Yes, if a lawnmower carburetor doesn’t need to be replaced, it can be cleaned without removing. It would be best if you had a toolbox and aerosol cleaner or any other carburetor cleaner.

  • Step 1. Remove the air filters: Firstly, remove the air filter cover and then the outer surface plus carburetor linkage using a screwdriver.
  • Step 2. Dry the carburetor: Let the carburetor dry and start the engine. At this time, spray aerosol cleaner on the carburetor and remove dirt from its lower throttle plate.
  • Step 3. Clean the choke: Also, apply aerosol on the choke shaft, which is at the base of the carburetor’s throat.
  • Step 4. Assemble the rest: To finish, the carburetor cover and linkage should be replaced, and the remaining parts assembled.

2. What is the method of using carburetor cleaner?

The carburetor should be cleaned regularly because of the dirt and debris that gets stuck in it and reduces the engine’s efficiency. Turn the machine on and spray carburetor cleaner round and down the throat to remove all the dirt and debris trapped in that zone. Also, spray at choke valve shaft of the carburetor at both ends.

3. How to clean Briggs and Stratton carburetor?

First, clean the outside of the carburetor, which may be covered with oil, grease, or dirt. Apply carburetor cleaner on its outside and also blow compressed air to clean every particle on the outer side. The butterfly’s floral shaft should move freely, so spray down the shaft and outside at the butterfly to make it free. Open the bolt at the butterfly’s opposite side and clean the hole (the spot from where fuel moves from the carburetor to the engine) in the bolt.

Spray at the removed cover, and then there is float having a pin, so pull it out. Take the float and needle out, and spray them properly. There is a hole in the carburetor body, spray carburetor cleaner inside, and it would come back from the downside. There would be a brass insert having a tiny hole. Clean it with a thin wire from a wire brush and spray it with carburetor cleaner. Spray in the main nozzle of the carburetor with carburetor cleaner.

Final Remarks:

A carburetor is the core element that keeps your Lawnmower running strong and perform better. The lawnmower carburetor ensures that the proper mixture of fuel and air will enter the engine cylinder for combustion. When ignited by the spark plug, the fuel and air mixture will combust, forcing the engine piston downward, which rotates the crankshaft causing the lawnmower blade to spin and the lawnmower wheels or riding mower wheels to turn.

The most censorious component for the functionality of a Lawnmower is the carburetor. It decides whether our Lawnmower will provide service for years or fizzles early. When you learn how to tidy out your lawnmower carburetor, you can always retain your Lawnmower in tip-top condition irrespective of its operating conditions.

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