You keep your Simplicity mower well-maintained by changing the filters, completing regular hydraulic and engine oil changes, keeping it clean, and using fresh fuel.
Even after taking all of these steps to extend the life of your mower, there are still times when you’ll encounter troubles due to regular wear and tear on the mower whether it’s a lawn tractor, riding mower, or zero-turn.
I have put together tables listing causes and solutions to many common problems. You will also find links to more in-depth articles to help with troubleshooting.
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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.
Common Simplicity Mower Problems
1. Mower Won’t Start
When your Simplicity mower fails to start, you’ll need to look for items that will keep the engine from getting gas, air, and spark.
In addition to this, make sure you are following the appropriate steps to start your mower. These include setting the parking brake and making sure the PTO switch is off before attempting to start the mower.
Detailed information can be found at:
Reasons a Simplicity Lawn Mower Won’t Start
| Cause | Reason for Problem | Solution |
|---|---|---|
| No gas in the fuel tank | Gas 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 | Use a thin piece of wire to try to clear 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 carburetor 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 all of the components carburetor. Rebuild or replace it if needed. |
| Bad battery or loose & dirty terminals | A dead battery, loose cables, or corroded terminals can cause starting problems | 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 | Your mower will not start when the ignition switch is faulty. | 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 if broken parts, like the pulley, can be replaced. Replace the recoil assembly if needed. |
2. Mower Loses Power and Dies
Most of the items that may prevent your Simplicity from starting can also be the reason your mower dies after it’s been running.
Make sure the choke setting is correct or the engine may die after you start it. This is because the choke is used to start a cold engine and must be moved to the off position once the engine warms.
If it isn’t adjusted correctly, the engine will begin to run sluggish and die because it isn’t getting enough air.
Detailed information can be found at:
Simplicity Mower or Zero Turn 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 | 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 |
| Bad Fuel Pump | The fuel pump is used to move gas to the carburetor when the carburetor sits higher than the fuel tank. | Replace a bad fuel pump. |
| Dirty carburetor | The carburetor can become dirty and clogged due to bad fuel and ethanol deposits preventing fuel flow | Clean all of the components making up the carburetor. Replace if needed. |
| Bad Gas Cap | When the gas cap won’t allow air to pass through it to vent the fuel tank, a vacuum forms restricting fuel flow. | Replace a bad gas cap. |
| Wrong Engine Oil Level | Too little engine oil can cause increased friction and heat in the crankcase. Too much oil will build pressure in the crankcase. | Correct the engine oil level. Contact an engine mechanic for assistance if this does not solve the problem. You may have engine damage. |
| Plugged Mower Deck | A deck packed with grass clippings and debris can put an extra load on the engine and may cause it to die. | Scrape the mower deck regularly to keep it clean. Avoid cutting wet grass as it is more prone to sticking to the deck. |
| Bad Ignition Coil | The coil can separate and short out when hot keeping voltage from getting to the spark plug. | Replace an ignition coil that has a break in continuity. |
| Dirty Spark Plug | A dirty spark plug may cause an intermittent spark. | Clean the spark plug or replace it when it is extremely dirty or worn. |
3. Lawn Mower Smokes
You will see smoke coming from your Simplicity when oil is burning off of a hot surface, the engine overheats, or the mower has internal engine damage.
Detailed information can be found at:
Reasons Your Lawn Mower May Be 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. |
| Low engine oil level | Lack of oil can increase friction in your engine causing extreme heat in the engine | Bring to a small engine repair shop to inspect engine damage. You can try adding oil, but it is often too late to fix your engine problem with this simple fix. |
| Internal problems including the piston ring, valve train, or engine gasket | Internal engine problems can have a detrimental effect on your mower if they are not caught soon enough and fixed. | Bring your Simplicity to your local small engine repair shop for troubleshooting |
4. Weak Hydrostatic Transmission
Simplicity lawn tractors and zero-turns utilize a hydrostatic transmission. You may experience a weak transmission when the hydraulic is old or low in capacity.
It can also feel weak when the drive belt or tensioner pulley is worn or broken.
| Cause | Reason for Problem | Solution |
|---|---|---|
| Bad drive belt | A bad drive belt can cause your pump not to work efficiently | Replace a frayed 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 Simplicity. Check your hydraulic oil periodically to ensure your hydraulic fluid is full. |
5. Mower Won’t Drive Straight or Steer Correctly
Several items can affect your Simplicity mower’s steering including incorrect tire pressures, bad dampers, and worn steering components. The tracking may be off on a zero-turn causing the mower to pull to the right or left.
| 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 | Replace with a new damper |
| Tracking adjustment needed on zero turn | When one tire is moving faster than the other, your mower can pull to one side | Adjust the speed adjustment bolt to change the rotation speed of the tire. Refer to your owner’s manual. |
| Worn or loose steering components in riding mower | Worn bushings, washers, and gears can cause your mower to not steer one way or the other | Inspect and replace the parts that failed on your steering system |
6. Lawn Mower Won’t Move
A Simplicity mower may not move due to a bad or missing drive belt, worn tensioner pulley, or missing idler spring.
The transmission bypass rod or the drive release lever smay be in the wrong position on a hydrostatic riding mower or zero-turn mower.
There is also the possibility you have air in the hydraulic system or you have transmission damage.
Detailed information can be found at:
Simplicity Zero Turn Won’t Move Forward or Reverse
| Cause | Reason for Problem | Solution |
|---|---|---|
| Drive release lever or bypass rod is in the wrong position | The drive release lever allows hydrostatic mowers to roll freely on a zero-turn. A bypass rod can be found on a riding mower. | The drive release lever must be in the operating position on a zero-turn. The bypass rod must be disengaged. |
| 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 belt. Make sure the belt is securely around the pulleys. |
| Bad tensioner pulley | The bearing in the tensioner pulley can fail | Replace 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 Simplicity. 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 Simplicity 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 procedures for removing air from the system. |
7. Mower is Vibrating
A Simplicity may be vibrating because of loose components and hardware on the mower; worn parts, unbalanced blades, and debris lodged in the mower.
Detailed information can be found at:
Simplicity Mower is Vibrating & Shaking
| 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 |
| Failing clutch | 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 | Blades must be balanced before installing them on the mower. Vibration can be caused by unbalanced or damaged blades. | Replace any damaged blades and make sure they are balanced. |
| Foreign material wrapped around the blade shaft | 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 | Confirm vibration is not coming from bad bearings in the spindle housing | Replace the bearing in the spindle housing or replace the whole spindle housing assembly |
| Bad deck belt or pulleys | Check deck belt and pulleys for wear and bearing failure | Replace any damaged or worn belts and pulleys |
| Debris lodged in mower | Stones, acorns, woodchips, and other small items can get lodged in the mower under the pulleys or other items on your mower. Sometimes this causes your mower to shake. | Check over your mower deck and mower for any place small items can be stuck in your mower. Remove these foreign materials. |
8. Mower Quits When Hot
There are many reasons a Simplicity mower will stop running once it gets hot. This is often caused by fuel-related issues, the wrong engine oil, the wrong amount of engine oil, plugged cooling fins, a bad ignition coil, or plugged mower deck.
Detailed information can be found at:
Your Mower Quits When It Gets Hot
| 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. |
| Bad or Old Fuel | Fuel breaks down over time leaving behind varnish and sticky deposits. | Drain old fuel. Fill with fresh gas with an added fuel system cleaner and stabilizers like Sea Foam or STA-BIL. |
| Dirty Carburetor | The residue left behind by old fuel can build up and clog the fuel jet or cause internal components to fail to work. | Remove the carburetor and clean it with a carburetor cleaner. Rebuild or replace it if necessary. |
| Wrong Engine Oil | Using the wrong type of oil or the wrong viscosity can cause the engine to run hot. | Use air-cooled engine oil like the oils provided by Kawasaki. See the oil viscosity chart in Things That Cause a Lawn Mower to Overheat |
| Too Much Engine Oil | 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. |
| Too Little Engine Oil | Lack of oil can increase friction in your engine causing extreme heat in the engine | Bring to a small engine repair shop or Simplicity dealership to inspect engine damage. You can try adding oil, but it is often too late to fix your engine problem. |
| Clogged Engine Cooling Fins | The buildup of dirt and debris in the cooling fins can restrict air movement. The cooling fins push air around the engine black to keep it cool. | Clean the cooling fins and replace any broken fins. Clean around the engine block and under the engine shroud. |
| Bad Ignition Coil | The coil can fail to work when it gets hot and the windings on the coil separate. | Use an ohmmeter to test the ignition coil. Replace when you find a break in the continuity. |
| Plugged Mower Deck | A deck plugged with grass clippings will prevent the blades from easily turning under the deck. A clogged deck puts the engine under load. | Regularly scrape the mower deck to keep it clean. Avoid cutting wet grass to reduce buildup. |
| Internal problems including the piston ring, valve train, or engine gasket | Internal engine problems can have a detrimental effect on your mower if they are not caught soon enough and fixed. | Bring your Simplicity to your local small engine repair shop for troubleshooting |
9. Mower is Running Rough or Sputtering
A Simplicity lawn mower that runs rough or bogs down can be due to a lack of air, fuel, or spark.
You may also experience this when you overwork the engine with a fast ground speed, low engine speed, plugged mower deck, or dull lawn mower blades.
Detailed information can be found at:
Reasons Your Lawn Mower is Running Rough
| 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. |
| Stuck Choke or Wrong Choke Setting | When the choke is set incorrectly the mower may begin to run rough because it is getting too much or too little air. | The choke must be adjusted to the open position once the engine is warm. Check the choke lever placement, the choke cable, and the choke plate. |
| Old fuel | Fuel breaks down and leaves behind varnish that can cause fuel restrictions and component failures. | Drain the fuel tank and fill it with fresh fuel mixed with a fuel additive like Sea Foam to clean the fuel system and stabilize the fuel. |
| Clogged Fuel Line | A clogged fuel line will restrict fuel flow. | Remove the clog in the fuel line using carburetor cleaner and compressed air. Replace the line if it is showing signs of age including cracks. |
| Plugged Fuel Filter | Dirt can clog the fuel filter restricting fuel flow. | Replace a plugged fuel filter. |
| Dirty Carburetor | Varnish left behind by old fuel can clog passageways and cause internal parts to stick. | Remove and clean the carburetor. Rebuild or replace if necessary. |
| Bad Gas Cap | When a gas cap no longer allows the fuel tank to vent, the tank will form a vacuum keeping sufficient fuel from getting to the carburetor. | Replace with a new gas cap. |
| Dirty Spark Plug | A dirty spark plug may cause an intermittent spark. | Replace with a new spark plug. Make sure it is gapped correctly and the spark plug wire is securely attached. |
| Fast Ground Speed | Running your Simplicity at a fast ground speed when mowing thick, tall, or wet grass may cause the engine to work hard. | Slow down and operate the mower at a speed that matches the mowing conditions. |
| Low Engine Speed | Engaging the mower blades requires a lot of engine power. When operating at a low engine speed, the mower will run sluggish and bog down. | Place the throttle lever in its highest position. |
| Plugged Mower Deck | The engine must work harder to turn blades through a deck packed with grass clippings and debris. | Scrape the mower deck. |
| Dull Mower Blades | Dull blades turning through a plugged mower deck further places the engine under load. | Remove and sharpen the mower blades. Balance them before reinstalling. |
10. Mower Blades Won’t Engage
When the mower blades won’t engage, it’s time to look at items that will fail to engage the clutch.
This could be the battery and PTO switch on models with an electric clutch or choke cable and linkages on models with a manual engagement clutch.
Detailed information can be found at:
Simplicity Mower Blades Won’t Engage or Turn On
| Cause | Reason for Problem | Solution |
|---|---|---|
| Worn Deck Belt | A worn belt is unable to grip the pulleys to turn the blades. | Replace a belt that is worn, cracked, or shiny in appearance. |
| Belt Coming Off of the Pulleys | A worn idler arm and spring may fail to keep tension on the belt. The belt may be stretched and loose. The pulleys may not sit parallel to the deck causing the belt to come off. | Replace worn or damaged deck parts. Replace a deck belt that is stretched. Ensure the belt is routed correctly around the pulleys. |
| Bad PTO Switch | When the PTO switch fails to allow the battery to energize the clutch the blades won’t turn on. | Replace a bad PTO switch |
| Bad Clutch | The clutch is unable to transfer power from the engine to the blades when it is faulty or worn. | Replace a bad clutch. |
| Worn Clutch Cable, Lever, Spring & Linkages | A manual engagement clutch may not work when the clutch cable, lever, spring, or linkages are worn. | Replace worn parts. |
| Weak Battery | A weak battery is unable to power the clutch. | Test the battery and place it on a charger if the 12-volt battery has a reading of less than 12.7 volts. |
| Bad Safety Switch | When the seat switch doesn’t sense the operator, it won’t allow the blades to be engaged. | Replace a bad battery. |
| Blown Fuse | The fuse can blow to protect the electrical system. The mower components will not receive the required battery power. | Replace a blown fuse with the same amperage fuse. Have a mechanic find the root cause when the mower continues to blow a fuse. |
11. Mower is Leaking Gas
It can be hard to find a leak on a Simplicity mower especially when you don’t catch the leak before the gas residue evaporates.
The best thing to do is follow the fuel line out of the fuel tank and check all of the components in the path of the line. If you still can’t find a leak, check for a leak from a bad gas cap seal.
Detailed information can be found at:
Simplicity Lawn Mower is Leaking Gas
| Cause | Reason for Problem | Solution |
|---|---|---|
| Bad Carburetor Bowl Gasket | The gasket becomes dry and fails to seal allowing gas to begin leaking. | Replace the carburetor bowl gasket. |
| Stuck Carburetor Float or Float Needle | Old gas can cause the float or float needle to stick allowing fuel to overflow. | Clean the carburetor and replace any damaged parts. |
| Cracked Fuel Lines | Old fuel lines can develop cracks. | Replace an old dry fuel line. |
| Bad Fuel Tank | Poly tanks can degrade and begin leaking at the seams. | Replace the fuel tank. Patch the tank when a new fuel tank is unavailable. |
| Bad Fuel Shut-Off Valve | A shut-off valve can develop a leak. | Replace the shut-off valve. |
| Weak Fuel Filter | Fuel can degrade plastic in the fuel filter or the plastic housing can crack. | Replace the fuel filter. |
| Bad Fuel Pump | The fuel pump can degrade and become weak at the seams. | Replace the fuel pump |
| Bad Gas Cap Seal | The seal in the gas cap can dry out and fail to seal. | Replace the fuel cap. |
| Cracked Primer Bulb | The bulb can crack or the line may be loose behind the primer bulb. | Replace with a new primer bulb. |
12. Mower Clicks and Won’t Turn Over
Detailed information can be found at:
Lawn Mower Clicks But Won’t Start or Turn Over
You may hear a click or hum and the Simplicity engine won’t turn over. This can happen when the mower isn’t getting power to the starter to turn over the engine.
While this is most likely caused by a bad starter solenoid, you will also need to check the items that prevent the solenoid from getting power.
| Cause | Reason for Problem | Solution |
|---|---|---|
| Damaged or Loose Battery Cables & Wiring | Loose or corroded wiring, cables, or terminals can prevent good conductivity. | Remove corrosion and replaced damaged components. Make sure wiring and cables are securely attached. |
| Weak or Bad Battery | A weak battery won’t provide the power needed to start and turn over the engine. | Test the battery and place it on a trickle charger if needed. Replace a battery that won’t hold a charge. |
| Bad Ground | The ground cable from the battery and the ground cable from the starter solenoid must make good contact and be free of corrosion. (A 3-post solenoid is self-grounded). | Remove any corrosion and make sure it is securely grounded to the mower. |
| Bad Starter Solenoid | The starter solenoid can fail and will no longer actuate to engage the starter motor. | Test the starter solenoid and replace it if faulty. |
| Bad Starter Motor | A bad starter motor will keep the motor from starting. | Replace the starter motor. |
13. Mower Has a Bad or Uneven Cut
There are several items that can cause a Simplicity to provide a bad cut. Start by checking the tire pressures and then move on to checking the components on the mower deck.
There is the possibility that the mower is working as designed. You just need to slow down for your conditions.
Detailed information can be found at:
Simplicity Lawn Mower Has a Bad or Uneven Cut
| Dull or worn mower blade | Tire pressures uneven | Engine speed is too low |
| Bent mower blade | Mower deck is not level | Ground speed is too fast |
| Blade installed wrong | Blade spindle is bent | Deck is damaged |
| Deck is plugged with dirt | Bad mower deck belt or pulleys | Operator error |
14. Engine Overheats
When the engine smells hot, you must stop running the engine right away to avoid causing extensive engine damage.
Begin to look for items that can cause the engine to get hot like using the wrong engine oil, not using enough oil, and debris packed around the engine and cooling fins.
Detailed information can be found at:
Things That Can Cause a Lawn Mower to Overheat
| Cause | Reason for Problem | Solution |
|---|---|---|
| Wrong engine oil | Using the wrong oil for the ambient temperatures or oil not designed for air-cooled engines can cause the engine to run hot. | Drain the engine oil and fill it with fresh air-cooled engine oil with a viscosity that works best for outdoor temperatures. |
| Low engine oil level | Lack of lubrication causes increased friction and heat. | Change the engine oil and add fresh oil. Low oil may have caused engine damage that should be diagnosed by a small engine mechanic. |
| Plugged engine cooling fins | Plugged or damaged cooling fins are unable to move air to cool the cylinder heads and engine block. | Clean plugged cooling fins. Replace damaged fins. |
| Engine guard missing or out of place | The engine guard shields the engine to keep air circulating around the engine to keep it cool. | Securely attach the engine guard. |
| Plugged air filter | A very dirty air filter will starve the engine of air causing it to work harder to find air. | Replace the dirty air filter. |
| Mower deck full of debris | Engine work harder to turn blades through a deck full of debris. | Scrape the mower deck to remove debris. |
| Dull mower blades | Dull mower blades magnify the problem of a plugged deck. | Sharpen and Balance the mower blades. |
| Overworking the engine | Cutting long, wet, or thick grass can overwork the engine, especially when attempting more grass than the mower can handle at once. | Slow down to match your mowing conditions. Avoid cutting wet grass. Double or triple-cut an overgrown lawn. |