How to Remove and Rebuild a Lawn Mower Carburetor

lawn mower carburetor
  • 13-4 hours
  • Intermediate
  • 100
What You'll Need
Hex wrenches (various sizes)
Pair of pliers
Disposable rags
Drain pan for used gas
Small pry bar
Lubricating gel
Cotton wool
Brush
6 inch bolts
Swivel screws
Wrench
What You'll Need
Hex wrenches (various sizes)
Pair of pliers
Disposable rags
Drain pan for used gas
Small pry bar
Lubricating gel
Cotton wool
Brush
6 inch bolts
Swivel screws
Wrench

Sometimes, removing a lawn mower carburetor is the only way you can clean and maintain it. If the carburetor gets water in it or becomes clogged with dirt, you'll want to take it off the mower to either clean it or replace it. This is a simple job that takes about five minutes to perform. Rebuilding it, however, takes much longer and is a bit more complicated.

Lawn Mower Carburetor

A lawn mower carburetor, located inside the lawn mower's engine, cycles gas from the gas tank and through an air filter. By doing so, it creates a spark-ignition engine.

Location

A lawn mower carburetor is generally located behind the air filter inside of the engine. Don't confuse the lawn mower carburetor with the muffler. These are generally on opposite sides of the engine.

Removing the Carburetor

small lawnmower carburetor

Before making any repairs, cleaning, or doing maintenance, you'll need to remove the carburetor. Doing so is actually a really easy job, but read your owner's manual for instructions on your specific brand and model of mower, as some may vary.

Step 1 - Drain the Fuel

Drain as much gas from the mower as possible into a pan. Some mowers have a fuel shutoff switch on the line that leads to the carburetor. If yours has one, you can simply flip this switch. Removing the fuel will make it much safer and cleaner to remove the carburetor later on.

Step 2 - Remove the Air Filter

To access the lawn mower carburetor, you'll sometimes have to take off the air filter, but this can vary depending on what make and model of lawn mower you have.

An air filter is attached with a hex nut and comes off easily. Make sure to put the hex nut and anything else you remove in zip lock bags and safely to the side. This will ensure you don't misplace anything before it's time to rebuild. You should also consider taking a photo so you know where everything is supposed to go.

You should now be able to see the carburetor.

Step 3 - Remove Fuel Hose

Place disposable rags under the carburetor to catch any fuel that drips. Using the pliers, gently pull the fuel hose out of the lawn mower carburetor. Take care not to pinch the hose. Doing so could damage your lawn mower.

Step 4 - Remove Lawn Mower Carburetor

The carburetor should be attached with a single hex nut. Remove the nut with a hex wrench. Twist the carburetor to the side so it detaches from the linkage, and remove it from the lawn mower.

Rebuilding the Carburetor

small carburetors

A lawn mower carburetor is an important part that helps mowers function. By mixing the right doses of air with gas, the carburetor is responsible for the running of an engine in an automobile.

The principle on which the lawn mower carburetor functions is not different from that of car or bike carburetors, but these are smaller, less complicated, and easier to rebuild at home.

Step 1 - Gather Parts

To rebuild the lawn mower, all the parts need to be detached from the setup and then examined for repairs. After each separate part is checked and dealt with, the carburetor can be set back into place.

You need to know the parts present in a lawn mower carburetor:

  • Air filter
  • Choke valve
  • Metering rod
  • Float valve
  • Nozzle

Step 2 - Work on Air Filter

Right at the top part of the carburetor, there should be a filter. Locate this and place a small flat prying bar at its base. Pry it up by applying gentle force, making sure you don't end up breaking it. It should come off easily.

If there's any rust on the filter, it will require a little more force. Take a thick bristled brush and rub vigorously on the area around the air filter. This is needed to remove any rust or layers formed that might damage the filter.

If the filter is rust-free, fit it back in place. If not, insert a new filter in the hole and press down till it fits snugly.

Step 3 - Adjust the Valve

Using a screwdriver, loosen the screw that holds the choke valve in place. Once the screw is out, you can see the areas in the valve where the screw was present.

Take some lubricating gel and spread it evenly all along the portion.

Now take a new screw and place it back in the place where the screw was removed from. Tighten it with a screwdriver.

Check if the valve is rotating smoothly by tapping, after applying the grease.

Step 4 - Work on Metering Rod

Find the fuel supply unit and loosen the bolts that secure its side panels to open it up. You should see a thin rod inside called the carburetor metering rod.

Using a wrench, loosen the small bolt that holds the rod in place with the link inside. Once this is done, the metering rod will fall free so you can take it out. Wipe the rod thoroughly using some cotton wool to clean off grease and other residues.

In cases where the layers are stubborn, add an auto part cleaner to the cotton wool and wipe away.

Now, apply some lubricating gel to the link by which the rod was connected. Check that the link is moving without obstructions by giving it a gentle tap.

Replace the rod as it was before, connect to the link, and tighten the bolt using the wrench. You may use a new bolt if needed.

Step 5 - Adjust Nozzle and Float Valve

There's a tiny nozzle for the intake of fuel attached to the air filter. Take a thin brush with wire bristles and insert it into the nozzle carefully. Clean the nozzle channel by wiping it with the brush.

Similarly, use the brush to clean and scrub the chamber where the floating valve is attached. See if the parts are rusted. If so, the valve needs to be taken out after loosening its bolt with a wrench. Take a new valve and attach it using the bolt in the proper place. If there's no rust, clean with cotton wool.

Cleaning Without Removing

small carburetor

If you want an easier project, there are methods available that allow you to clean a lawn mower carburetor without disassembling it and removing it from the lawn mower. This is actually an easy task and you have a few different options for how to do it.

Unless there's a severe clog in your lawn mower carburetor, you may be able to clean it simply by using a compressed air gun. Aim the compressed air gun at the dirty areas of the lawn mower carburetor. This will help to remove grease and other residues that have accumulated over time. After you're done with the compressed air gun, clean the upper tray of the lawn mower as well.

Another way to clean the lawn mower carburetor without removing it is by using a commercial lawn mower carburetor cleaner. This usually comes in the form of a spray can which can be used on the entirety of the lawn mower carburetor.

There are also ways to clean the lawn mower carburetor that involve vacuuming. To use this approach, start by putting on protective gear like safety gloves, safety goggles, and a face mask. You also must make sure the lawn mower is off before starting this project.

Once everything is safely off, you can use a handheld and cordless vacuum to get rid of some of the gunk and debris. Make sure the vacuum is not too powerful, as that could harm the carburetor. You can apply cleaner after you have managed to vacuum away some of the bigger pieces of gunk.

Briggs and Stratton Engine Carburetor Removal

Removing the engine carburetor in a Briggs and Stratton lawn mower is similar to how you would remove any other lawn mower engine carburetor. To start, disconnect the spark plug lead and secure it away from the spark plug. This will ensure nothing sparks and harms you while you are dealing with the rest of this process.

Once the spark plug lead is disconnected and secured away from the spark plug, you can remove the air cleaner assembly. You can now turn off the fuel valve. This can be found on the base of the fuel tank in your Briggs and Stratton lawn mower.

In some instances, however, there will not be a fuel valve. If this is the case with your particular lawn mower, you will need to instead use a fuel line clamp. This will prevent fuel from draining once you disconnect the carburetor from the engine.

If your engine has an electrical device at the base of the fuel bowl, disconnect this as well.

You can now start to unfasten the carburetor mounting bolts. Take a picture before you start, and keep everything you unfasten in a zip lock bag. Not putting the bolts back correctly could have dangerous effects later.

If there's a pipe connecting the carburetor to the engine block, remove these bolts as well. Put them in a separate zip lock bag so that you do not confuse the two. Make sure to label both bags appropriately.

You can now disconnect the carburetor from the pipe. To do so, remove the nuts then disconnect the governor springs and remove the carburetor. Make sure you are careful when you remove it so as not to ding it or any other piece of your lawn mower.

There you have it, how to remove the engine carburetor from your Briggs and Stratton lawn mower.

    Craftsman Engine Carburetor Removal

    Like Briggs and Stratton, Craftsman is another common type of lawn mower. Before you remove the lawn mower engine carburetor in these models, you'll need to stop the fuel from flowing. Not doing so could hurt you while you are working on the device.

    To stop the flow of fuel from moving around the lawn mower, use the fuel shut-off valve. Like with other lawn mowers, this should be on the bottom of your tank. Like with other lawn mowers, if you don't have a shut-off valve, make sure to clamp the fuel line instead.

    Now detatch the throttle cables as well as the choke cables from your carburetor. Once these are both detached, you can remove the nuts and bolts or other securing devices used to attach the carburetor to the air filter housing.

    You can now remove the springs from your carburetor as well. Once the springs have been removed you can remove the bowl from the carburetor. It's usually located on the bottom of the device. To do so, you'll need to remove the screw on the bottom of the bowl and use caution when removing it so as to not stretch anything or spill any fuel.

    You can now clean out the lawn mower engine carburetor.

    Other Mower Projects

    Once you've got your lawn mower back in action, take a look at our guides to mowing your lawn to get the healthiest grass.