Your riding lawn mower carburetor controls the amount of air and fuel mixture to form combustion in your engine.
When the carburetor isn’t functioning correctly, it can cause your riding mower to sputter, stall and not start. Most of the time, your carburetor problems can be solved by cleaning them.
If you are a little mechanical and don’t mind working with small parts, you can follow my instructions below to clean the carburetor yourself. Your local small engine repair shop is an option to have your carburetor cleaned or rebuilt if you don’t want to tackle the job.
Symptoms of a Bad Carburetor on Your Riding Lawn Mower
When a riding carburetor is acting up, you will notice these symptoms due to your mower running with the incorrect fuel-to-air mixture or having a blockage:
- Engine won’t start
- Starts and then dies
- Backfires from running lean
- Engine is sputtering and running rough
- Engine is surging
- Mower is consuming too much fuel
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Follow all safety instructions provided in your equipment operator’s manual before diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.
10 Steps to Clean Your Riding Mower Carburetor
Spray Carburetor Cleaner in the Air Intake: You don’t want to take your carburetor apart if it isn’t causing your problem. To identify if you need to take your carburetor apart, remove your air filter from the filter housing.
Spray carburetor cleaner into the air intake and start your riding mower. If your mower starts and then dies, you must take apart your carburetor and clean it.
Gather Tools and Items Required to Clean the Carburetor
- Pliers
- Screwdriver
- Socket/ratchet set
- Carburetor cleaner
- Thick wire
- Needle nose pliers
Take Photos for Reassembly
I highly recommend taking photos during the disassembly of your carburetor. There are so many small parts to your carburetor that it can be hard to remember where every part to when you reassemble it.
Most people have a cell phone available to take photos and easily access them. If you have a camera or phone, take photos of your carburetor before you remove it and during each step of taking it apart.
Shut off Your Fuel Supply
Use your fuel shut-off valve to stop fuel flow. You will find this valve at the bottom of your fuel tank. If you don’t have a shut-off valve, crimp the line to stop fuel flow. Remove the fuel line from the carburetor.
Remove the Throttle & Choke Cable
Remove your throttle and choke cables.
Detach the Filter Housing
Remove the hardware that attaches the carburetor to the air filter housing.
Remove the Springs on Your Carburetor
Next, you need to slowly remove the springs. Be careful to not stretch out the springs. You may have to twist the carburetor a bit to get the springs to come off.
Be careful not to tear the gasket located between the engine block and the carburetor. If you do tear it, you will need to replace it with a new gasket.
Remove the Bowl from Your Carburetor
The carburetor bowl stores a little gasoline inside your carburetor. The bowl is located on the bottom of your carburetor and is held on by a screw. Have a rag available to catch any remaining gas in the bowl.
Go ahead and remove the screw and the bowl while taking care not to damage the gasket that sits between the bowl and the carburetor.
This gasket looks like a rubber band. You don’t want any substance such as carburetor cleaner to get on the gasket or you will need to replace it.
Check the Stem for Clogged Holes
There is a little piece that hangs down from the center of your riding mower’s carburetor. This is known as the stem. There are holes in the stem that can become clogged from running old fuel.
When this happens, the stem will not draw fuel up to the jet. Use a flashlight to better see the holes in the stem. Clean the holes with a thick wire to unplug the holes.
Check Your Carburetor for White Crusty Buildup
Check out the carburetor and its parts for a white crusty buildup which is the result of fuel additives including ethanol. Try to remove as much of this crusty material as possible using carburetor cleaner. It is almost impossible to remove all the crusty deposits.
Use the carburetor cleaner to clean any parts that are sticking or clogged.
Reassemble Your Carburetor
Once you have cleaned your carburetor and ensured the float and float needle are moving freely, it’s time to reassemble it. Reference the photos you took earlier when putting your carburetor together to make sure all the small parts get put back in the right places.
Reattach components to your riding mower carburetor including the springs, filter housing, throttle and choke cables (if the mower uses them), and the fuel line.
Fill Your Fuel Tank with Fresh Gas with a Fuel Additive
Start your fuel flow. Use fresh gasoline mixed with a fuel additive, like Sea Foam Motor Treatment, in your riding mower’s fuel tank. Give the fuel a chance to fill the bowl of your carburetor and start your engine.
Read more about why I choose to use Sea Foam to stabilize and clean my fuel system with my article on the advantages of Sea Foam here.
Replace or Rebuild Your Carburetor
Sometimes cleaning your carburetor doesn’t get the carburetor working again. You may have too much buildup or parts of your carburetor may become stuck or damaged. In this case, you will have to rebuild or replace your carburetor.
Check the price for a carburetor rebuild kit and the price for a new carburetor. Sometimes the prices aren’t that far apart and you may choose to replace your carburetor instead of rebuilding it.
When purchasing parts for your carburetor, have your engine’s make and model number available. Many lawn tractors use another manufacturer’s engine so you need to have the engine information on hand to ensure you get the right parts.
Riding Mower Problems Could Be More than a Carburetor Problem
A dirty or bad carburetor can be a cause of your riding mower not starting, quitting after starting, and leaking fuel. There are many other items that can cause these problems. To find out more about these causes and how to solve them, check out the links below.
Still Having Problems With Your Riding Mower?
As a lawn mower owner, when you own it long enough, you are going to run into different types of problems. This may include problems where your mower is smoking, cutting unevenly, losing power, not starting, leaking fuel, and more.
Check out this handy guide including charts for common mower problems and solutions:
Common Riding Lawn Mower Problems & Solutions.
If you are unable to fix your mower or don’t want to attempt a more complicated repair, have your local lawn mower dealership or repair shop for assistance.
Larry Whitt
Tuesday 11th of July 2023
Engine run s great until blade engages, runs for 10 feet, sputters engine dies if you don’t disengage blade immediately.
Equipment Blog Team
Wednesday 12th of July 2023
Doesn't sound like a safety switch issue since you were able to run the blades and move the mower for about 10 feet. I would start with looking at things that can cause the engine to be overworked. This could be due to a wrong fuel/air mixture, clogged mower deck, mowing tall or thick grass. Check to make sure nothing is keeping the belts from moving freely.