How to Clean Lawn Mower Carburetor

There is nothing more annoying than a temperamental lawn mower on a sultry summer day. You are all set to start mowing only this time, one, two, or even three pulls on the starting rope produce a desultory gurgle or a puff of dirty black smoke from the mower. In this situation, one needs to accept that after three pulls on the starting rope, if you aren’t able to start it; then it is very likely that something is amiss.

Assuming that there is plenty of fuel in the tank, you may discover that the issue lies in the carburetor. Of course, the lawn mower carburetor is never the sole reason why your lawn mower may die suddenly. But there are times when the carburetor is improperly adjusted or clogged with sediment and dirt.

Therefore, periodic cleaning of carburetor on a riding lawn mower or a push lawn mower at regular intervals is necessary to keep the mower in good condition. A lot of starting headaches and costly repairs can be forestalled with simple cleaning steps for the lawn mower carburetor. In this guide, we are discussing the steps you can follow for cleaning a lawn mower carburetor:

How to Clean Out a Lawn Mower Carburetor

Step 1: Getting Started: Tools and Equipment Needed

Gather all the tools needed. An old toothbrush and a rag, different sized wrenches and screwdrivers, an empty cup to collect the fuel, carburetor cleaner, a spark plug gapper, pliers, new gaskets, new air filters, and a light lubricant are some of the tools you need to clean a carburetor on a push lawn mower. These days, a carburetor cleaning kit is also readily available.

Always buy new parts like gaskets and seals because these parts harden and may develop leaks. Remember safety first! Always wear a set of protective eye goggles and a mask while servicing the carburetor. Always read the service manual for carburetor troubleshooting. These manuals have step-by-step cleaning and adjustment procedures to cure specific issues. If needed, get a buddy or a partner to help you.

Step 2: Make Preliminary Checks

Ensure that professional servicing is not needed to clean out a lawn mower carburetor. You can do so by checking if the mower’s ignition feeds spark to the cylinder. To check ignition, remove the spark plug from the engine. You must also know the symptoms of a clogged carburetor.

There are many signs and symptoms of a clogged carburetor. The main ones are failed engine performance, black exhaust smoke, difficulty in starting the mower, and backfiring. The mower may also overheat. With regular cleaning, a lawn mower carburetor can ensure great performance and prevent these issues.

Step 3: Check for Good Ignition

Get someone to pull the starter rope as you hold the spark plug against the engine. Hold the spark plug by its rubber end to avoid getting shocked. Also, keep it away from the plug hole to avoid igniting the gasoline pumped into the engine. With the engine turning, you should see a strong, steady spark at the tip of the plug.

Step 4: Ensure That the Crankshaft is in Proper Position

With the plug removed, pull the starter rope or spin the blade. Check the blade for wobble which signals a bent crankshaft. Press against the blade’s non cutting edge and give it a forceful spin, pulling your hand away immediately. If the blade wobbles, the crankshaft is bent.

Step 5: Gain Access to the Gas Tank and Engine

With screwdrivers, remove the screws that secure the plastic cover and lift it off. Also, remove and replace dirty paper filters. After removing and replacing air filters, clean the filter backing plate with a toothbrush. Keep dirt away from carburetor.

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Step 6: Disconnect the Fuel Lines

Drain the gas tank into the empty container. You can use a set of pliers to control the rate of flow.

Step 7: Check the Float Levels

One of the basic steps how to clean a carburetor on a lawn mower is checking the float levels. Your lawn mower must come with an instruction manual, so check the manufacturer’s recommendations for float levels. Adjust your carburetor float level with that of the manufacturer’s specification. This is the simplest and first step in the lawn mower carburetor cleaning process.

Step 8: Ensure That Carburetor Float is Not Stuck

If the carburetor float is stuck, the engine will not idle. A flooded carburetor is also another sign indicating a stuck float level. Your mower might also stall or hesitate or misfire.

Step 9: Replace Old Gaskets

When you add the new gaskets, do make sure that they are properly seated and the bolts drawn to uniform tension. Renew the gaskets periodically as a part of your routine of cleaning a lawn mower carburetor.

Step 10: Clean the Sediment Bowl

Examine and clean the sediment bowl. Remove the bowl and clean it thoroughly. It is also important to renew the gasket periodically.

Step 11: Perform Oil Change

Change the oil and flush out the crankcase often. Be sure to use the oil specified by the manufacturer of the engine.

Step 12: Watch Out for Air Leaks

Air leaks between the carburetor and engine are a common cause of fuel-mixture troubles. The tiny leaks are also difficult to locate and remedy. It is important to place the gaskets carefully to avoid leaks. If, at any time, you have to adjust needle valve or idling adjustments, be especially careful not to screw the needles down in their seats in fuel jets.

Never attempt to clean the jets with wires or sharp tools. If the jets are clogged, disassemble the carburetor and blow out passages individually with compressed air.

Step 13: Clean the Gas Tank

To clean the gas tank, remove it, swirl it with some gas and then empty it. Repeat with a few ounces of fresh gas.

Step 14: Remove Trapped Grass Clippings on Flywheel

Loosen and remove the bolts that secure the metal air shroud. Lift the air shroud from the engine and look for dirt and trapped grass blades on the flywheel and carburetor. Use a screwdriver to remove the trapped debris from the cylinder head, flywheel fins, and carburetor body.

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Step 15: Clean Jet Orifices

Remove the knurled nut from the fuel bowl bottom and carefully lower the bowl away from the carburetor. Use a brush or a thin wire to clear dust, rust, and varnish deposits from the jet’s orifice. Always ensure using a wire that is thinner than the jet orifice to prevent damage to the jets.

Step 16: Spray the Carburetor Cleaner

Spray the carburetor cleaner into the top and bottom of the carburetor. This helps dissolve deposits of old gas. While spraying, make sure you cover your nose and mouth. If you have one, wear a respirator mask – this is especially necessary while working in a closed garage.

Also, spray the top of the carburetor. This will dissolve sticky deposits left behind by stake gas. You can even spray the cleaner on the choke shaft which is located at the base of the carburetor.

Step 17: Adjust the Lawn Mower Carburetor

An important part of lawn mower carburetor cleaning is how to adjust a lawn mower carburetor. Here are the steps of adjusting lawn mower carburetor:

• Before doing any adjustments, inspect engine for air cleaner condition and any vacuum leaks.
• Start the engine and allow it to warm up. Make sure the choke valve is fully open.
• Open the throttle to operate the engine at the speed specified in the manufacturer’s manual.
• Insert a screwdriver into the high speed mixture screw. Turn the screw in to lean the mixture until the engine runs rough. Turn the mixture screw out to enrich the mixture until the engine runs as fast as it will run.
• Allow the engine to return to idle. Insert the screwdriver into the low-speed mixture screw. Turn the screw in to lean the mixture until the engines runs rough. Turn the mixture screw out to enrich the mixture until the engine runs as fast as it will run.
• Insert the screwdriver into the idle speed adjustment screw. Rotate the screw in a direction to increase or reduce idle speed, until the desired speed is met.

Step 18: Put Everything Back

Install the bowl and tighten the bowl nut. Reinstall the air shroud and the gas tank. Push the gas line and primer tube into the carburetor nipples. Also, install the air filter housing backing plate with a clean filter. Tighten down the filter cover and replace the engine cover.

Conclusion

We hope that this guide has helped you get the steps of how to clean lawn mower carburetor. You can also learn how to clean a carburetor on a riding lawn mower procedure. You must always follow personal safety first before attempting to take apart the lawn mower. Protect your eyes with goggles and wear a respirator mask prior to using aerosol cleaners. When in doubt, it is best to seek professional help from an experienced lawn mower mechanic.