A Troy-Bilt push mower won’t start when there is a fuel restriction caused by a dirty carburetor, clogged fuel filter, bad fuel cap, or old fuel. It may also be the result of a clogged air filter or fouled spark plug.
Keep reading for additional items that can keep your mower from starting. Just make sure you take all safety precautions including removing the spark plug when performing repairs.
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.
BEGIN HERE: Troubleshoot a Troy-Bilt Push Mower Starting Problem
The small engine on a Troy-Bilt mower compresses a mixture of fuel and air. It then ignites the mixture with a spark to create combustion. To begin looking for the start issue, you need to verify the engine is getting sufficient fuel, air, and spark.
Before beginning to check for starting problems verify these 4 things:
- The fuel shut-off valve is open allowing fuel to flow out of the fuel tank. (If your model has one).
- There is sufficient fresh fuel in the fuel tank.
- The bail lever (safety lever) is engaged when attempting to start the mower.
- The choke is on and in the closed position to start a cold engine. (Note: most current models have an automatic choke. There isn’t a choke lever to open and close the choke).
Check for a Fuel Problem
Old gas is often the root cause for fuel-related issues resulting in components not functioning or clogs developing.
Before checking for a fuel problem, if your Troy-Bilt has a fuel shut-off valve, make sure it is in the open position. This valve is often moved to the closed position when the push mower is stored or when it is being transported.
Perform this test to narrow down your problem to the Troy-Bilt fuel system:
- Detach the air filter cover and remove the air filter.
- Spray carburetor cleaner into the air intake. Don’t use starter fluid. I’ve seen too much damage from using starter fluid.
- Attempt to start your mower using the manual recoil starter or turning the ignition key (depending on your mower type)
- If the mower attempts to start or starts, then you have a problem with the fuel system.
- The most common fuel issues are a dirty carburetor, a clogged fuel filter, and a clogged fuel line.
- If the mower doesn’t attempt to start, you most likely have a spark plug problem.
- If the mower attempts to start or starts, then you have a problem with the fuel system.
Check for an Airflow Problem
Air is an important component needed for your engine to start. The engine must run rich to start a cold engine. This condition allows more fuel and less air into the cylinder.
Airflow is controlled by the choke. You will find a choke lever that opens the choke plate to introduce more air and close the choke plate to restrict air.
On newer push mowers, you will find an automatic choke controlled by a thermostat near the muffler.
Perform this test to narrow down your problem to the air supply system:
- Detach the air filter cover and remove the air filter.
- Inspect the air filter’s condition. A clogged air filter will restrict airflow. Clean the filter or replace it if it is very dirty or damaged.
- With the air filter removed, inspect the choke plate.
- Manual-choke model
- Move the choke lever to the on position: The choke plate should be closed.
- Move the choke lever to the off position (on some models, this is placing the throttle in the fast throttle position): The choke plate should be open.
- Auto-choke model
- The choke plate should be closed when the engine is cold and moved to the open position when the engine warms.
- Manual-choke model
- If the choke isn’t opening and closing correction, check the choke linkage and choke cable. Loosen a stuck choke by lubricating the linkages and choke shaft using carburetor cleaner. Replace a bad choke cable (if used on your model).
Check for a Spark Problem
Spark must be released at the right time for combustion. A spark plug may fail to spark if it is dirty or damaged. It may also fail due to a loose spark plug wire, a bad ignition coil (armature), or other ignition system problems.
Perform this test to narrow down your spark problem:
- Remove the spark plug wire (boot) from the spark plug.
- Attach a spark plug tester to the spark plug ignition wire.
- With the spark plug still installed, attach the other end of the spark plug tester to the spark plug.
- Attempt to start the engine using the pull cord or electric start.
- You will see a glow in the transparent section of the tester if it is generating a spark.
- If you don’t see a glow, the spark plug may be bad or you may have a bad ignition coil. On electric start models, you may have a problem with the ignition system including the battery, wiring, and starter solenoid.
16 Reasons Your Troy-Bilt Push Mower Won’t Start
1. No Fuel
Okay, don’t think this isn’t getting to be a helpful article because I mention lack of fuel. It’s happened to the best of us. You think there’s no way I could be out of fuel and start looking for other reasons your Troy-Bilt won’t start.
Push mowers have very small fuel tanks and you may have run out of gas sooner than you thought. You may have developed a fuel leak causing you to run through gas faster than usual.
SOLUTION: Fill your gas-powered 4-cycle push mower with gasoline that has an octane rating of 87 or higher and an ethanol level no greater than 10%. You can read more about gas for 4-cycle and 2-cycle push mowers here.
2. Bad or Old Gas
It doesn’t take long for gas to begin to cause problems in the fuel system. That’s why small engine manufacturers recommend consuming fresh fuel within 30 days of purchase.
The ethanol used in most gas attracts moisture to the fuel system. A gummy substance is left behind that can clog the fuel system and leave behind crusty material in the carburetor.
Keep these things in mind when purchasing and storing fuel:
- Purchase fresh gasoline with a minimum 87-octane rating.
- Make sure it contains no more than 10% ethanol.
- 4-cycle engines require straight gas. 2-cycle engines require a gas and 2-cycle oil mixture.
- Consume fuel within 30 days.
- Use a fuel additive like Sea Foam Motor Treatment or STA-BIL to keep fuel stable so it last a little longer before it breaks down. While I try to consume fuel within 30 days, I always use a fuel additive just in case.
- Store fuel in a cool dry location.
SOLUTION: Remove the old fuel. It’s best to use a fuel siphon pump for this. You can also try to remove the fuel line from the carburetor and place it in a container to drain the tank.
Mix fresh fuel with a fuel additive to clean your fuel system and stabilize it. I have had good results using a product called Sea Foam Motor Treatment. You can read more about why I use Sea Foam here.
Add the fuel mixture to the fuel tank. Start the mower, if you are able to at this time, and allow it to run and work its way through the fuel system.
3. Bad Fuel Cap
Another item that can cause a fuel restriction is the fuel cap. Your Troy-Bilt gas cap will have a vent built into it to allow air to pass through the cap and into the fuel tank as fuel is consumed.
When the vent is no longer working, the tank will form a vacuum. This will keep fuel from flowing out of the tank and to the carburetor.
To isolate your cap as being the cause of your starting problem, loosen the cap and attempt to start your Troy-Bilt mower. If it starts and runs, tighten the fuel cap while allowing the engine to continue to run to attempt to replicate the problem.
If your engine begins to run sluggishly and/or shuts down, loosen the cap to allow air into the tank to check if the engine begins to run better.
SOLUTION: You may be able to clean your fuel cap and unclog the vent. If I find the cap is the problem, I prefer to replace it with a new one.
4. Bad Spark Plug or Loose Connection
A spark plug may no longer work and cause intermittent starting and running issues with your mower. A spark plug that is dirty from carbon buildup must be cleaned or replaced if the tip appears very dark in color.
A damaged spark plug that has a broke porcelain insulator or burnt electrode must be replaced as well. To minimize the problems you have during the mowing season from a spark plug, it is best to start each season with a new plug.
Starting problems can also be caused by a spark plug that is incorrectly gapped or has loose spark plug connections.
SOLUTION: Remove your spark plug and inspect it for signs of carbon buildup or cracked porcelain insulators. Replace with a new spark plug.
Make sure to gap them according to manufacturer specifications and that the spark plug wires are securely attached.
5. Clogged Air Filter
A push mower requires clean air to run. The air filter prevents dirt and debris from entering the air intake and contaminating the engine. Dirt in the engine can cause significant engine damage.
Never run your Troy-Bilt mower without an air filter even if it’s only for a short period of time while you source a new filter.
When an air filter gets clogged so air is no longer able to pass through the filter, your mower won’t start. It is important to regularly check the air filter and keep it clean.
By checking, cleaning, and replacing this inexpensive part when needed, you can prevent an expensive engine repair.
SOLUTION: Carefully remove the air filter from the air filter housing so you don’t allow dirt to fall into the air intake. If you find dirt in the housing, wipe it out with a clean cloth. Follow one of the following procedures for your type of air filter:
Clean a PAPER push mower air filter
- Knock out the excess dirt in the filter by tapping it against a solid surface.
- Hold the filter up to a light source and check for light shining through the paper element.
- Reuse the filter if you can see light pass through the paper. If you cannot, replace your filter with a new air filter.
- Install the air filter and attach the cover.
Clean a FOAM push mower air filter
- Determine whether you can reuse your filter before cleaning it. If your filter has dark spots or is dry and brittle, replace the filter with a new one.
- If your filter is in good condition, proceed with washing it with mild dish soap and water to remove dirt from the filter.
- Rinse the filter and lay it flat to dry. Placing it outdoors in the sun will speed up the process.
- Once the filter is dry or if you are using a new foam filter, add a foam filter oil to lightly saturate the filter. You don’t want it dripping with oil.
- Install the filter into the housing and attach the cover.
6. Clogged Fuel Filter
Your push mower will have a fuel filter to strain the fuel coming out of the fuel tank to keep dirt and other contaminants from entering the fuel system and causing damage to fuel components and the engine.
This filter can become clogged and will need to be changed.
You may have an inline fuel filter inserted between the fuel lines, but you most likely won’t be able to see your fuel filter. This is because the filter is a narrow filter inserted into the fuel line off the fuel tank.
SOLUTION: Replace a clogged fuel filter. If you don’t visibly see an inline fuel filter, you’re going to want to check the bottom of the fuel tank. You may be able to shine a flashlight into the tank to see if you can see the filter.
If you can, you’ll have to drain the fuel tank and remove the fuel line from the bottom of the fuel tank. Remove the old filter, insert a new filter into the fuel line, and reattach the fuel line.
7. Clogged Fuel Line
A push mower fuel line can become clogged by dirt and the sticky substance left behind by old gasoline. This keeps fuel from getting to your carburetor and to your engine. Read more about identifying a clogged fuel line here.
SOLUTION: Remove the fuel line, spray carburetor cleaner into the tube, and use compressed air to blow air through the tube until the line is free of dirt and gummy residue. Repeat as necessary. Replace the fuel line with a new line when you can’t remove the clog.
8. Dirty Carburetor
Your mower uses a carburetor to regulate the amount of gas mixed with air allowed into the cylinder for combustion.
The additives added to fuel, including ethanol, can cause gummy substances to form in your carburetor. The substance clogs the small parts in your carburetor restricting fuel.
SOLUTION: If you are somewhat mechanical, you can try to clean the carburetor on your push mower. If you are not, have a local repair shop perform the work.
You may choose to replace the carburetor if it appears to be in very bad condition or if you don’t want to attempt to clean it.
9. Bad Troy-Bilt Safety Switch
The safety switch is designed to kill the engine when the operator is no longer present. If you let go of the bail lever, also referred to as the safety lever, the engine stops.
A faulty switch may not recognize when the bail lever is engaged to start the Troy-Bilt mower. Refer to your operator’s manual for other types of safety switches that may be used on your model lawn mower.
SOLUTION: You can temporarily bypass the safety switch to identify a bad switch. Do not operate your mower without the safety switch installed for your safety. Always have safety switches installed and working on your equipment. Replace a bad switch.
10. Sheared Flywheel Key
A sheared flywheel key may cause your starting issue because the timing is off. Correct timing is when the spark plug releases spark once the piston compresses the right amount of air and fuel mixture for combustion.
When the timing is off, your engine won’t get the optimal power to start or run at its best.
So what causes the flywheel key to shear? Most likely, the key will shear when the blade hits something solid.
The crankshaft is attached to the blade on a crankshaft. So when the crankshaft suddenly stops, the flywheel doesn’t stop as fast resulting in a sheared flywheel key. The timing is now off.
Another reason the key may shear is from running a loose blade.
SOLUTION: Inspect the flywheel key and replace a broke one.
11. Bad Recoil (Manual Start)
Manual start Troy-Bilt push mowers utilize a recoil to start the mower. The recoil can break and you are no longer able to start your mower.
SOLUTION: If the rope is no longer wrapped around your recoil, you may be able to restring it to get it working again. You may have a broken pulley, spring, or clips that need to be replaced.
If you find broken parts, you should price out the parts in addition to the whole recoil assembly. It may be more cost-effective to replace your recoil.
12. Bad Battery or Loose Wiring (Electric Start)
Lawn mowers with an electric start require a power source like a battery. Make sure your cables and battery terminals are secure.
Clean any corrosion you find on your terminals using a baking soda solution (2 cups water to 3 heaping tablespoons of baking soda). Once you confirm you have a good connection, continue testing the battery.
SOLUTION: Test your battery with a multimeter. Replace a bad Troy-Bilt battery.
13. Bad Ignition Switch (Electric Start)
Your lawn may have an ignition switch that has failed. If you press the ignition switch and nothing happens, you need to check your switch using a multimeter.
SOLUTION: Replace the ignition switch if it is bad.
14. Bad Starter Solenoid (Electric Start)
A lawn mower solenoid is an electromagnetic switch like an on-off switch that actuates the starter motor to turn over the engine.
A click or hum when turning your ignition key is an indication to check your solenoid. Another indication your solenoid may be bad is when a wire attached to your Troy-Bilt solenoid gets hot and begins to smoke or melt.
SOLUTION: Test your lawn mower solenoid by following the steps here. Replace your solenoid/starter if it is found to be bad.
15. Blown Fuse (Electric Start)
The fuse is used to protect the electrical system. Check for a blown fuse that can keep your Troy-Bilt push mower from starting. You will find the fuse near the battery.
SOLUTION: Replace a blown fuse
16. Incorrect Starting and Operating Procedure
Troy-Bilt won’t allow your mower to start unless you follow its starting procedures. This may be engaging the bail lever and adjusting the choke.
Starting procedures may vary slightly depending on the model you are using.
SOLUTION: Refer to your operating manual to ensure you are operating your lawn mower correctly, so you don’t set off the safety features that shut off your push mower or don’t allow it to start.
When to Consult a Professional Mechanic
If you’ve gone through this list of the most common reasons for a Troy-Bilt starting issue and you still can’t get it started, you may want to consult a small engine mechanic.
Throwing parts at your mower while guessing what the problem is isn’t the answer. You may have more serious engine issues that need to be diagnosed and an experienced mechanic will be able to run tests to check the engine.