As much as you don’t want to have failures develop in your zero turn mower, it’s bound to happen. Any mechanical item will wear down and fail over time.
You can prevent many of these issues by regularly servicing your mower. Neglecting regular oil changes and replacing filters may void any warranty remaining on your zero-turn.
I put together a list of the most common problems you will see as a Bad Boy lawn mower owner. This is a handy guide to keep on hand to refer to next time you encounter an issue.
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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.
Troubleshooting Common Bad Boy Mower Problems
1. Won’t Start
A mower, like all fuel-powered mowers, requires air, fuel, spark, and compression to start and run. When it lacks any of these items, your mower will fail to start.
This could be a result of old fuel, clogged fuel components, a dirty carburetor, a plugged air filter, or a bad spark plug. Your mower may also fail to start if you have electrical problems including a bad switch, ignition coil, or bad battery.
Detailed information can be found at:
Lawn Mower Won’t Start: Solved!
| Cause | Reason for Problem | Solution |
| No gas in the fuel tank | Fuel tank is empty | Fill with fresh fuel |
| Bad or old fuel | Fuel breaks down overtime making your fuel less efficient and prone to clogging the fuel system | Drain the fuel tank and fill it with fresh fuel. Use a fuel additive like Sea Foam to stabilize the fuel and assist with cleaning the fuel system. Use the right fuel. |
| Faulty or clogged fuel cap | The vent in the cap can get clogged causing your tank to form a vacuum restricting fuel flow | Try to clean the cap and remove the clogged vent. Replace the cap if needed. |
| Bad spark plug | Excessively dirty or broken spark plug; bad connection; not gapped correctly | Replace with a new spark plug, secure connections, and ensure it is gapped to manufacturer specifications |
| Plugged air filter | Dirt and grass can plug the air filter preventing airflow | Remove the filter and clean it. Replace the filter if it is in bad condition. |
| Plugged fuel filter | A dirty fuel filter will restrict fuel flow | Replace the fuel filter |
| Bad fuel pump | A failed or leaking fuel pump will no longer create the pressure needed to pump fuel | Replace the fuel pump |
| Blocked fuel lines | Bad fuel deposits and dirt can build up and clog the fuel lines preventing the engine from getting the required fuel | Use a carb cleaner and compressed air to clear the clog out of the fuel line. Replace the line if necessary. |
| Dirty carburetor | The carburetor can become dirty and clogged due to bad fuel and ethanol deposits preventing fuel flow | Clean the components making up the carburetor. Replace if needed. |
| Bad battery or loose & dirty terminals | A dead battery, loose cables, or corroded terminals | Charge your battery and replace it if it won’t hold a charge. Make sure your cables are tight and clean the corrosion from terminals. |
| Bad safety switch | Safety switches are a safety measure that exists to prevent your mower from starting in certain situations. When a switch fails, your mower may not start. | Test and replace faulty safety switch |
| Bad ignition switch or coil | Your mower will not start when either the ignition switch or coil is bad | Test and replace a bad switch |
| Broken recoil | A pull start mower may have a damaged or broken recoil preventing the recoil to initiate starting your engine | Check the recoil to see if it can be restrung or broken parts, like the pulley, can be replaced. Replace the recoil assembly if needed. |
2. Loses Power and Dies
A zero turn can lose power and shut off when the mower has a fuel or air restriction from running bad fuel that clogs fuel components or from using a plugged air filter.
Your mower may also shut down when it overheats. Overheating can be caused by a lack of air in the engine, plugged engine cooling fins, or an insufficient engine oil level.
Not only is it important to check for items that can restrict air and fuel that can cause your mower to overheat, but you also need to look at your battery, charging system, spark plug, and ignition coil as well. These items can be the culprit of your mower’s running issue.
Detailed information can be found at:
Your Bad Boy Mower Starts Then Dies
| Cause | Reason for Problem | Solution |
| Bad fuel | Fuel breaks down overtime making your fuel less efficient and prone to clogging the fuel system and engine damage | Drain the fuel tank and fill it with fresh fuel. Use a fuel additive like Sea Foam to stabilize the fuel and assist with cleaning the fuel system |
| Plugged air filter | Dirt and grass can plug the air filter preventing airflow | Remove the filter and clean it. Replace the filter if it is in bad condition. |
| Dirty or broken cooling fins | Cooling fins get packed with dirt, oil, and grass not allowing air to effectively cool the engine block | Replace broken fins and clean the cooling fins. |
| Clogged fuel lines or filter | Bad fuel deposits and dirt can build up and clog the fuel lines preventing the engine from getting the required fuel | Use a carb cleaner and compressed air to clear the clog out of the fuel line. Replace a plugged fuel filter. |
| Dirty carburetor | The carburetor can become dirty and clogged due to bad fuel and ethanol deposits preventing fuel flow | Clean all components making up the carburetor. Replace if needed. |
| Too Much Engine Oil | Too much engine oil increases pressure in the crankcase causing it to overheat and die | Correct your engine oil level by removing a little oil |
| Bad Spark Plug | Dirty or damaged spark plug causes the plug to foul out and cause intermittent running issues. | Clean or replace spark plugs if needed. Ensure spark plug wires are securely attached and the plug is gapped correctly. |
| Faulty Ignition Coil | Windings on the coil can separate and short out a bad ignition coil | Check for a break in the continuity using an ohm meter and replace is found bad |
| Choke is in the Wrong Position | A choke is used for cold starts. The choke can cause your engine to shut off when it continues to restrict airflow after the engine warms. | Make sure the choke is in the correct position |
| Bad Gas Cap or Rollover Vents | A Bad Boy mower will vent the tank to allow air to pass through. When the vents get plugged, the fuel tank will cause fuel restrictions. | Replace a fuel cap or rollover vents when they become clogged and no longer vents |
| Clogged Mower Deck | Clogged mower deck causes a strain on the engine causing it to work hard and possibly shut down | Periodically scrape your mower deck to keep it clean |
3. Engine is Smoking
Smoke can be alarming. It may be the result of water in the fuel system or oil burning off a hot component. An engine oil leak or spill can cause smoke when the oil burns off of a hot component like the engine or muffler.
A smoking Bad Boy mower may be the result of a plugged air filter, insufficient engine oil level, engine gasket leak, valve train problem, or piston ring problem.
Detailed information can be found at:
Lawn Mower is Smoking
| Cause | Reason for Problem | Solution |
| Plugged air filter | Dirt and grass can plug the air filter preventing airflow | Remove the filter and clean it. Replace the filter if it is in bad condition. |
| Too much oil in the crankcase | Excessive oil can cause pressure to build in the engine allowing oil to get into the cylinder through the valve train | Drain a little engine oil until it is at the manufacturer’s recommended oil level. |
| Engine oil level is too low | Lack of oil can increase friction in your engine causing extreme heat. | Bring to a small engine repair shop to inspect engine damage. You can try adding oil, but it is often too late for this to fix your engine problem. |
| Internal engine issues including the piston ring, valve train, or engine gasket | Internal engine issues can have a detrimental effect on your mower if they are not caught soon enough and fixed. | Bring your mower to your local small engine repair shop for troubleshooting |
4. Weak Hydrostatic Transmission Problem
A hydrostatic transmission on a zero turn can feel weak from the use of a bad hydraulic belt or pulley. Old hydraulic oil, not having enough oil in the hydraulic tank, or developing a hydraulic leak in your mower can also result in a weak transmission.
When your mower feels weak on one side, the mower will not drive straight and can pull to one side.
Perform a hydraulic fluid change at regular intervals.
Note: Some transmissions are non-serviceable. This means you are unable to change the hydraulic oil because the system is sealed.
Bring your mower to your local lawn mower repair shop or Bad Boy dealership when you have issues with a non-serviceable hydraulic system or have more significant transaxle problems.
| Cause | Reason for Problem | Solution |
| Bad drive belt | A bad drive belt can cause your pump not to work efficiently | Replace a frayed, cracked, or worn belt |
| Bad tensioner pulley | When a tensioner pulley fails, it fails to keep tension on the drive belt | Replace the pulley and grease the tensioner arm |
| Low or old hydraulic oil | Low or old hydraulic oil can fail to lubricate the hydraulic system causing your hydraulic system to seem weak | Change your hydraulic oil at regular intervals as recommended by Bad Boy. Check your hydraulic oil periodically to ensure your hydraulic fluid is full. |
5. Isn’t Mowing Straight or Steering Correctly
Several items can affect your mower’s steering including incorrect tire pressures, worn steering dampers, or damaged castor wheels.
It is good to check the tracking on your mower. When the unit is not tracked correctly, your mower can veer off to one side and not drive straight.
| Cause | Reason for Problem | Solution |
| Incorrect tire pressure | Unequal tire pressure can cause your mower to pull to one side. | Check tire pressures and keep them filled to the manufacturer’s spec. Tires on each side of your mower require equal pressure. |
| Bad dampers on zero turn | Bad dampers will cause your mower to jerk to one side when moving forward | Fix with a new damper |
| Tracking adjustment needed on zero turn | When one tire is moving faster than the other, your zero turn can pull to one side | Adjust the speed adjustment bolt to change the rotation speed of the tire. Refer to your owner’s manual. |
6. Won’t Move
Before you check anything on your mower, first check to bypass drive release levers are not the cause of your moving problem. These levers are located at the rear of your mower on the right and left hand.
The levers will be pulled out to place your mower in the neutral position to disengage the hydros so you can manually roll the mower. Make sure these levers are in the operating position.
A bad drive belt, broken tensioner spring, or a worn tensioner pulley can all cause your zero turn not to move.
A hydraulic system problem where the fluid is hot, at a low level, or air is caught in the system can cause your mower to move slowly or not move at all.
Some hydraulic systems are sealed so you won’t be able to work on them. Take your mower to your local dealer for mower service.
Detailed information can be found at:
Reasons Your Bad Boy Mower Won’t Go Forward or Reverse
| Cause | Reason for Problem | Solution |
| Drive release lever in the wrong position | The drive release arms allow hydrostatic mowers to roll freely | The drive-release arms must be in the operating position. |
| Drive pump belt is worn | The mower won’t move if your drive belt has fallen off. It could also not move if the belt is worn. | Replace a worn or cracked belt. Make sure the belt is securely around the pulleys. |
| Bad tensioner pulley | The bearing in the tensioner pulley can fail | Fix by replacing the tensioner pulley. |
| Missing idler arm spring | If the idler arm spring breaks or goes missing, it can no longer place tension on the drive belt | Replace the broken or missing spring. |
| Low or old hydraulic oil | Low or old hydraulic oil can fail to lubricate the hydraulic system causing your hydraulic system to seem weak | Change your hydraulic oil at regular intervals as recommended by Bad Boy. Check your hydraulic oil periodically to ensure your hydraulic fluid is full. |
| Hot hydraulic fluid | Hot hydraulic fluid can be a sign of damage to your hydrostatic transmission system | Let your hydraulic oil cool. If you find your mower runs fine when it is cold, but becomes weak when the hydraulic system gets hot, have your mower checked at your local dealership. |
| Air in the hydraulic system | Air must be bled from the hydraulic system after changing your hydraulic fluid or the mower will not be able to move at normal speeds | Follow Bad Boy’s procedures for changing the hydraulic fluid and bleeding air from the system as outlined in your owner’s manual. |
7. Mower is Vibrating
Your mower naturally vibrates when operating normally. This vibration can intensify when there are loose or broken parts on your mower or your mower has worn linkages, a bad clutch, or debris stuck in your mower.
Even the smallest little item can cause a significant vibration so inspect your mower closely.
Bad deck components can also cause your mower to shake. This can from unbalanced mower blades; worn bearings in the spindle housings and pulleys; damaged spindles; a worn belt; or bent brackets.
Detailed information can be found at:
Your Bad Boy Lawn Mower is Vibrating
| Cause | Reason for Problem | Solution |
| Loose or missing engine mounting bolts | Engine bolts are used to reduce the vibration of the mower when the engine is running | Secure engine bolts and replace any missing bolts |
| Clutch is bad | When there is bearing failure and it falls out of the clutch it can cause vibration. A manual engagement clutch can have a bushing and linkages that can fail. | Replace the clutch |
| Unbalanced or damaged mower blades | Damaged and unbalanced blades can send a vibration through your mower. Blades must be balanced before installing | Replace any damaged blades and make sure they are balanced. |
| Material wrapped around the blade spindle | Foreign materials like string or long weeds can get wrapped around your blade shaft causing vibration | Remove all debris and items wrapped around the blade shaft. Check for spindle damage. |
| Bad spindle housing bearings | Vibration can be caused by a bad bearing in the spindle housing. | Replace the bearing in the spindle housing or replace the whole spindle housing assembly |
| Worn pulleys or deck belt | Check deck belt and pulleys for wearing of the belt and bearing failure in the pulleys | Replace any damaged or worn belts and pulleys |
| Debris lodged in mower | The smallest little things can cause your mower to excessively vibrate. Check over your mower for debris stuck in the deck or mower. Don’t overlook the small stuff. | Check over your mower deck and mower for any place small items can be stuck in your mower. Remove these foreign materials. |
8. Bad or Uneven Cut Problems
An uneven cut with your mower isn’t always a fault in the mower deck. It can be something as simple as a low tire that can make you’re your mower not sit level.
Always check the tire pressure first and then move on to looking at your mower deck.
Then check for a mower belt issue where the belt is worn, the belt tension is too loose or too tight, or the belt keeps coming off the mower deck.
Detailed information can be found at:
Reasons Your Bad Boy Lawn Mower Cuts Uneven
| Worn mower blade | Uneven tire pressures | Engine speed is too low |
| Bent mower blade | Unleveled mower deck | Ground speed is too fast |
| Blade installed wrong | Bent blade spindle or spindle bearing | Damaged deck shell |
| Clogged Mower Deck | Worn deck pulleys or belt | Operator error |
9. Leaking Gas
Locating the actual spot your lawn mower is leaking can be more challenging than you might think. You may not notice you have a gas leak until you see a trail of burnt grass or smell a strong odor in your storage shed.
By the time you get to look at your mower, the leaked fuel may have already evaporated into the air leaving no clues.
Your mower can develop leaks in the fuel system because old gas degrades your components over time. It can make mechanical parts fail or cause plastic housings to become weak and leak.
Detailed information can be found at:
Your Bad Boy Mower is Leaking Gas
| Cause | Reason for Problem | Solution |
| Dirty of Failed Carburetor | The carburetor can collect a buildup of substances remaining from old gas that can cause blockages or parts failures | Clean the carburetor and replace any damaged parts |
| Old Fuel Filter | Filter can become plugged | Replace the fuel filter |
| Bad Fuel Pump | Pump can wear and deteriorate over time and may begin leaking at the seams | Replace the fuel pump |
| Bad Fuel Tank | A poly tank can leak at the seams of the tank. | Replace the fuel tank. |
| Bad Fuel Shut-Off Valve | Metal and plastic shut-off valves are prone to leaking | Replace the shut-off valve |
| Cracked Fuel Lines | Rubber fuel lines become dry and cracked causing gas to leak | Replace the fuel lines |
| Bad Seal in the Gas Cap | The gas cap seal can fail and no longer seal allowing gas to splash out of the fuel tank around the gas cap | Replace the gas cap |
10. Won’t Turn Over
A zero turn mower that just clicks or hums and won’t start may have a bad starter solenoid. In addition to checking the solenoid, look for items that can affect power getting to the solenoid.
These include the battery, cables, terminals, and ground. When the fault doesn’t lie with any of these items, check the starter motor.
For More Information Check Out:
Bad Boy Mower Won’t Turn Over or Crank
| Cause | Reason for Problem | Solution |
|---|---|---|
| Damaged or loose battery cables & wiring | Loose wires and cables provide poor continuity. | Replace damaged cables. Remove any corrosion on the terminals or other components. Secure loose cables. |
| Weak or bad battery | Won’t provide the power needed to turn over the engine. | Test the battery and place it on a charger if the reading is less than 12.7 volts for a 12-volt battery. Replace the battery when it won’t hold a charge. |
| Bad ground | The ground wire absorbs excess power. | Remove corrosion from the ground. Make sure the ground cable from the battery and ground cable from the starter solenoid is making good contact. (A 3-post solenoid is self-grounded) |
| Faulty starter solenoid | The starter solenoid actuates the starter motor. | Test the starter solenoid and replace it if faulty. |
| Bad starter motor | The starter motor turns over the engine. | Replace a bad starter motor. |
11. Zero Turn Blades Won’t Engage or Turn On
The mower blades won’t engage when the PTO switch is faulty, the battery is weak, a safety switch failed or the clutch is bad.
The blades won’t turn when the belt is worn or has fallen off the pulleys due to a stretched belt, bad pulley bearing, or worn tensioner parts.
For More Information Check Out:
Bad Boy Mower Blades Won’t Engage or Turn On
| Cause | Reason for Problem | Solution |
|---|---|---|
| Worn mower deck belt | The worn belt won’t grip the pulleys to turn them to rotate the blades. | Replace a belt that is worn, cracked, or has a shiny glazed appearance. |
| Belt falls off the pulleys | Without a drive belt, the pulleys can’t turn to rotate the blades. | Replace worn or damaged deck parts including a worn idler arm, worn spring or bad pulleys. Replace a stretch mower deck belt. |
| Bad PTO switch | A failed switch won’t allow voltage from the battery to engage the clutch. | Replace the PTO switch. |
| Bad clutch | The clutch transfers power from the engine to the blades by engaging the drive belt. | Replace the clutch. On a manual engagement clutch, replace a worn clutch cable, lever, springs, and linkages. |
| Weak battery | The clutch is powered by the battery. | Test the battery and place it on a charger if the reading is less than 12.7 volts for a 12-volt battery. Replace the battery when it won’t hold a charge. |
| Bad safety switch | A bad switch may not allow the operator to engage the blades when the seat switch fails to recognize the operator in the seat. | Replace the safety switch |
| Blown fuse | A fuse may have blown to protect the electrical system. | Replace the fuse with a fuse with the same amperage. If it continues to blow, have a mechanic identify the root cause. |
12. Running Rough and Sputters
When you find your mower is running rough and bogs down, begin troubleshooting by looking for items that can restrict fuel flow or airflow or can cause an intermittent spark.
You’ll also need to look at items that can put extra load on the engine like a fast ground speed, plugged mower deck, and dull mower blades. Not having your throttle at its fastest speed can also cause the engine to run sluggishly when the blades are engaged.
For More Information Check Out:
Bad Boy Mower is Running Rough or Sputtering (Coming Soon)
| Cause | Reason for Problem | Solution |
|---|---|---|
| Old fuel | Old fuel buildup and varnish restrict fuel flow. | Drain old fuel. Refill with a gas and fuel stabilizer mixture. |
| Clogged fuel line | Old fuel deposits can stick to the fuel line narrowing the passageway through the fuel line. | Remove a clogged fuel line and remove the clog using carburetor cleaner and compressed air. Install a new fuel line when the clog can’t be removed. |
| Plugged fuel filter | A dirty fuel filter may keep a good flow of fuel from passing through it. | Replace the fuel filter. |
| Dirty carburetor | Varnish buildup can clog passageways. | Remove the carburetor to clean it. Rebuild or replace it if needed. |
| Bad gas cap | When the fuel tank vent in the gas cap is clogged, the fuel tank may form a vacuum reducing fuel flow. | Replace a gas cap that no longer allows the fuel tank to vent. |
| Dirty spark plug | Carbon buildup on a spark plug can cause intermittent starting. | Clean a dirty plug using a wire brush. Install a new one if it is very dark in color, worn, or damaged. |
| Fast ground speed | Trying to cut more grass at one time than the engine can handle can cause the engine to work harder. | Slow down the ground speed to match the mowing conditions. Slow down when mowing tall, thick, or wet grass so the engine isn’t under too much load. |
| Low engine speed | Running the mower blades requires a lot of engine power. | Place the throttle lever in its highest position when engaging the mower blades. |
| Plugged mower deck | The engine may be placed underload when it needs to work harder to turn the blades through a deck packed with grass clippings and debris. | Scrape the mower deck to keep it clean. |
| Dull mower blades | Dull blades further magnify the issue of overworking the engine due to a plugged mower deck. | Sharpen the mower blades. |
13. Overheating
Engine oil plays an important part in keeping the engine cool on a mower. Use an air-cooled engine oil of the right viscosity that is high in zinc. Keep the engine oil level full.
Check for items that can block airflow around the engine including the cooling fins, engine shroud, and engine guard.
Inspect the air filter, mower deck, and mower blade condition to prevent common overheating problems.
For More Information Check Out:
Engine Overheats
| Potential Cause | Solution | |
|---|---|---|
| Wrong engine oil | A Bad Boy mower requires an air-cooled engine oil with a high zinc content used as a cooling agent. Use oil that works best in for running a mower in your outdoor temperature ranges. | Drain the engine oil and fill it with fresh oil. Use 10W-30 oil in most conditions. You may have to use a different viscosity in very warm conditions. |
| Low engine oil level | Low oil reduces lubrication causing internal engine friction and heat. | Drain the fuel tank. Refill with a fresh gas with an additive to clean the fuel system and stabilize the fuel. |
| Plugged engine cooling fins | Engine cooling fins are used to push air around the cylinder heads and engine block to keep it cool. | Remove dirt and debris from the cooling fins, around the engine, and from air intakes. |
| MIssing engine guard | The engine guard helps keep air circulating around the engine instead of allowing the air to escape the area. | Replace a missing engine guard. Securely attach a loose guard. |
| Plugged air filter | The engine works harder when it is searching for clean air. | Replace a dirty air filter. |
| Plugged mower deck | The engine works harder to turn blades through a deck packed with grass clippings. | Scrape the mower deck to remove grass clippings and debris. |
| Dull mower blades | Dull blades magnify the problem of a plugged mower deck. | Sharpen dull mower blades. Replace worn blades. |
| Overworking the engine | Operating the mower at too fast of a speed for the mowing conditions can cause the engine to overload and overheat. | Slow down the ground speed to match the mowing conditions. Avoid cutting wet grass. Double or triple-cut an overgrown lawn. |
Find a Bad Boy Repair Shop Near You
Bad Boy LLC stands behind its products and offers a warranty to take care of any manufacturer defects and problems that develop in the mower’s initial years of operation.
While it is disappointing when you need a repair, unexpected failures may happen. You can find a repair shop near you by visiting Bad Boy’s website.
How Do You Know Whether Your Mower is Under Warranty?
Contact your local full-service Bad Boy dealership. The dealership will be able to look up warranty information on your mower and any recall notices issued on the mower.
Have your serial number ready to provide to the dealer personnel.