March 1, 2016

How to replace a lawn mower carburetor

By Lyle Weischwill
How to replace a lawn mower carburetor

This step-by-step lawn mower repair guide gives instructions for replacing a lawn mower carburetor. The carburetor blends air with fuel to form a combustible mixture that ignites in the cylinder to drive the piston. If the carburetor is clogged or damaged, the engine runs rough or won’t start. If the carburetor is clogged or damaged, replace it with a manufacturer-approved replacement part. Use these steps to replace the carburetor on common Briggs & Stratton engines that power Craftsman, MTD, Husqvarna, Poulan, Murray, Toro, Troybilt and Ariens walk-behind lawn mowers. If you'd rather rebuild the carburetor, How to Rebuild a Lawn Mower Carburetor shows you how.

Quick links
Tools required
Nut driver set
Pliers
Shop rag
Fuel-safe container
Work gloves
Repair difficulty
Time required
30 minutes or less
Repair difficulty
Time required
30 minutes or less
Replacing a carburetor on a lawn mower

This video explains how to replace the carburetor on a walk-behind lawn mower.

Instructions

01.

Disconnect the spark plug wire

Working in a well-ventilated area, disconnect the spark plug wire from the spark plug.

Disconnect the spark plug.

Disconnect the spark plug.

02.

Remove the air filter housing

Release the catch and pull the air filter cover off.

Remove the air filter.

Remove the screws from the air filter base.

Release the breather tube and pull off the air filter base.

Pull off the air filter base.

Pull off the air filter base.

03.

Drain the fuel tank

Place a shop rag under the fuel tank to catch spills.

Place a fuel-safe container under the gas line connection to the fuel tank.

Release the spring clamp and disconnect the fuel line from the gas tank.

Drain the gasoline into the container.

Wipe up any spills.

Drain the gasoline.

Drain the gasoline.

04.

Remove the blower housing

Release the starter rope from the mower handle.

Remove the screws from the blower housing.

Pull the blower housing off the engine.

Remove the blower housing.

Remove the blower housing.

05.

Remove the carburetor

Separate the carburetor mounting bracket arms to release the carburetor and disconnect the carburetor from the carburetor adapter.

Holding the carburetor above the bracket, disconnect the governor and choke linkage rods and remove the carburetor.

Release the fuel line spring clamp and pull the fuel line off the carburetor.

Remove the carburetor from the lawn mower.

Remove the carburetor from the lawn mower.

06.

Install the new carburetor

Push the O-ring into the outlet port of the new carburetor.

Install the retainer on top of the O-ring.

Connect the fuel line to the new carburetor and secure it with the spring clamp.

Hold the carburetor over the mounting brackets and connect the governor and choke linkage rods.

Push the carburetor into the bracket arms and push the outlet port fully onto the carburetor adapter.

Push the air cleaner gasket into the channel on the carburetor inlet.

Install the new carburetor.

Install the new carburetor.

07.

Reinstall the blower housing

Position the blower housing on the top of the engine and line up the mounting holes.

Reinstall the blower housing mounting screws.

Reconnect the starter rope to the mower handle.

Reinstall the blower housing.

Reinstall the blower housing.

08.

Reconnect the fuel line to the tank

Push the fuel line onto the tank fitting and secure it with the spring clamp.

Reconnect the fuel line to the tank.

Reconnect the fuel line to the tank.

09.

Reinstall the air filter housing

Position the air filter base on the front of the carburetor and reconnect the breather tube.

Secure the air filter base with the mounting screws.

Reinstall the air filter.

Position the air filter cover on the front of the base and snap it into place, engaging the locking tab.

Reinstall the air filter base.

Reinstall the air filter base.

10.

Reconnect the spark plug wire

Push the spark plug wire back onto the spark plug.

Warning: Undertaking repairs or maintenance to appliances or power equipment can be hazardous. Should you choose to undertake repairs or maintenance, you are assuming the risk of injury to your person or property. In an effort to reduce the risk, use the proper tools and safety equipment noted in the applicable guide and follow all instructions. Do not proceed until you are confident that you understand all of the steps and are capable of completing the repair. Some repairs or maintenance, however, should only be performed by a qualified technician.
Symptoms for gas walk-behind mowers

Choose a symptom to see related walk-behind mower repairs.

Main causes: drive control cable failure, worn or broken drive belt, bad transmission, broken drive wheel
Main causes: damaged cutting blade, loose cutting blade, damaged flywheel key, engine needs tune up
Main causes: dirty carburetor, bad spark plug, clogged air filter, engine choke problems, clogged gas cap vent
Main causes: stale gas, engine needs tune up, bad spark plug, dead battery, bad recoil starter, faulty safety switch, bad ignition coil
Main causes: engine needs tune up, dirty or clogged carburetor, damaged flywheel key
Main causes: uneven wheel height settings, damaged wheel, dull or damaged cutting blade
Repair guides for gas walk-behind mowers

These step-by-step repair guides will help you safely fix what’s broken on your walk-behind lawn mower.

How to replace a lawn mower ignition coil on an OHV engine

Replace the ignition coil if it isn't sending electric current to the spark plug when you pull the recoil starter rope.

Repair difficulty
Time required
 30 minutes or less
How to replace a lawn mower flywheel key on an OHV engine

The flywheel key couples the flywheel to the engine crankshaft. Replace the flywheel key if it's broken.

Repair difficulty
Time required
 60 minutes or less
March 1, 2016
By Lyle Weischwill
How to replace a lawn mower drive cable

The drive cable engages the transmission to spin the drive wheels and move the mower across the grass. Replace the drive cable if it's broken or frozen up inside the sheath.

Repair difficulty
Time required
 60 minutes or less
Articles and videos for gas walk-behind mowers

Use the advice and tips in these articles and videos to get the most out of your walk-behind lawn mower.

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How to tune up a lawn mower video
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See how to tune up your mower once a year to keep it running well.

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6 weeks to a better lawn
By Erin Hynes

Do these 5 things this spring for a lawn that's healthier all summer.

April 1, 2015
How to keep grass clippings from sticking to a mower deck
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Prevent your mower deck from rusting by following our advice for keeping grass clippings from sticking.