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Troubleshoot 14 Simplicity Mower Problems: SOLVED

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 indepth articles to help with troubleshooting.

14 common problems in a Simplicity lawn mower are:

  1. Failure to start
  2. Loses power and dies
  3. Begins smoking
  4. Has a weak hydrostatic transmission
  5. Won’t drive straight or steer correctly
  6. Won’t move forward or reverse
  7. Mower is vibrating
  8. Mower quits when hot
  9. Runs rough or sputters
  10. Mower blades won’t engage
  11. Leaking gas
  12. Clicks and won’t turn over
  13. Has a bad or uneven cut
  14. Mower overheats
Simplicity lawn mower

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Follow all safety instructions provided in your equipment operator’s manual prior to 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.

Simplicity Mower Problem 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

CauseReason for ProblemSolution
No gas in the fuel tankGas tank is emptyFill with fresh fuel
Bad or old fuelFuel breaks down overtime making your fuel less efficient and prone to clogging the fuel systemDrain 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 capThe vent in the cap can get clogged causing your tank to form a vacuum restricting fuel flowUse a thin piece of wire to try to clear the clogged vent. Replace the cap if needed.
Bad spark plugExcessively dirty or broken spark plug; bad connection; not gapped correctlyReplace with a new spark plug, secure connections, and ensure it is gapped to manufacturer specifications
Plugged air filterDirt and grass can plug the air filter preventing airflowRemove the filter and clean it. Replace the filter if it is in bad condition.
Plugged fuel filterA dirty fuel filter will restrict fuel flowReplace the fuel filter
Bad fuel pumpA failed or leaking fuel pump will no longer create the pressure needed to pump fuelReplace the fuel pump
Blocked fuel linesBad fuel deposits and dirt can build up and clog the fuel lines preventing the engine from getting the required fuelUse a carburetor cleaner and compressed air to clear the clog out of the fuel line. Replace the line if necessary.
Dirty carburetorThe carburetor can become dirty and clogged due to bad fuel and ethanol deposits preventing fuel flowClean all of the components carburetor. Rebuild or replace it if needed.
Bad battery or loose & dirty terminalsA dead battery, loose cables, or corroded terminals can cause starting problemsCharge 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 switchSafety 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 switchYour mower will not start when the ignition switch is faulty.Test and replace a bad switch.
Broken recoilA pull start mower may have a damaged or broken recoil preventing the recoil to initiate starting your engineCheck 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.
Simplicity Starting Problems and Solutions

Simplicity Mower Problem 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

CauseReason for ProblemSolution
Bad fuelFuel breaks down overtime making your fuel less efficient and prone to clogging the fuel system and engine damageDrain 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 filterDirt and grass can plug the air filter preventing airflowRemove the filter and clean it. Replace the filter if it is in bad condition.
Dirty or broken cooling finsCooling fins get packed with dirt, oil, and grass not allowing air to effectively cool the engine blockReplace broken fins and clean the cooling fins.
Clogged fuel linesBad 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 PumpThe 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 carburetorThe carburetor can become dirty and clogged due to bad fuel and ethanol deposits preventing fuel flowClean all of the components making up the carburetor. Replace if needed.
Bad Gas CapWhen 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 LevelToo 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 DeckA 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 CoilThe 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 PlugA dirty spark plug may cause an intermittent spark.Clean the spark plug or replace it when it is extremely dirty or worn.
Reasons Your Simplicity Mower Loses Power and Dies

Simplicity Mower Problem 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

CauseReason for ProblemSolution
Plugged air filterDirt and grass can plug the air filter preventing airflowRemove the filter and clean it. Replace the filter if it is in bad condition.
Too much oil in the crankcaseExcessive oil can cause pressure to build in the engine allowing oil to get into the cylinder through the valve trainDrain a little engine oil until it is at the manufacturer’s recommended oil level.
Low engine oil levelLack of oil can increase friction in your engine causing extreme heat in the engineBring 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 gasketInternal 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
Simplicity Lawn Mower Smoking Problems

Simplicity Mower Problem 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.

CauseReason for ProblemSolution
Bad drive beltA bad drive belt can cause your pump not to work efficientlyReplace a frayed or worn belt
Bad tensioner pulleyWhen a tensioner pulley fails, it fails to keep tension on the drive beltReplace the pulley and grease the tensioner arm
Low or old hydraulic oilLow or old hydraulic oil can fail to lubricate the hydraulic system causing your hydraulic system to seem weakChange your hydraulic oil at regular intervals as recommended by Simplicity.
Check your hydraulic oil periodically to ensure your hydraulic fluid is full.
Why Your Simplicity Hydrostatic Transmission Seems Weak

Simplicity Mower Problem 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.

CauseReason for ProblemSolution
Incorrect tire pressureUnequal 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 turnBad dampers will cause your mower to jerk to one side when moving forwardReplace with a new damper
Tracking adjustment needed on zero turnWhen one tire is moving faster than the other, your mower can pull to one sideAdjust 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 mowerWorn bushings, washers, and gears can cause your mower to not steer one way or the otherInspect and replace the parts that failed on your steering system
Why Your Simplicity Mower Won’t Drive Straight or Steer Correctly

Simplicity Mower Problem 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

CauseReason for ProblemSolution
Drive release lever or bypass rod is in the wrong positionThe 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 wornThe 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 pulleyThe bearing in the tensioner pulley can failReplace the tensioner pulley
Missing idler arm springIf the idler arm spring breaks or goes missing, it can no longer place tension on the drive beltReplace the broken or missing spring
Low or old hydraulic oilLow or old hydraulic oil can fail to lubricate the hydraulic system causing your hydraulic system to seem weakChange your hydraulic oil at regular intervals as recommended by Simplicity.
Check your hydraulic oil periodically to ensure your hydraulic fluid is full.
Hot hydraulic fluidHot hydraulic fluid can be a sign of damage to your hydrostatic transmission systemLet 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 systemAir must be bled from the hydraulic system after changing your hydraulic fluid or the mower will not be able to move at normal speedsFollow procedures for removing air from the system.
Reasons Your Simplicity Lawn Mower Won’t Move

Simplicity Mower Problem 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

CauseReason for ProblemSolution
Loose or missing engine mounting boltsEngine bolts are used to reduce the vibration of the mower when the engine is runningSecure engine bolts and replace any missing bolts
Failing clutchWhen 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 bladesBlades 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 shaftForeign materials like string or long weeds can get wrapped around your blade shaft causing vibrationRemove all debris and items wrapped around the blade shaft. Check for spindle damage.
Bad spindle housing bearingsConfirm 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 pulleysCheck deck belt and pulleys for wear and bearing failureReplace any damaged or worn belts and pulleys
Debris lodged in mowerStones, 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.
Why Your Simplicity Mower is Vibrating

Simplicity Mower Problem 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

CauseReason for ProblemSolution
Plugged air filterDirt and grass can plug the air filter preventing airflowRemove the filter and clean it. Replace the filter if it is in bad condition.
Bad or Old FuelFuel breaks down over time leaving behind varnish and sticky deposits.Drain old fuel. Fill with fresh gas with an added fuel system cleaner and stabilizer like Sea Foam or STA-BIL.
Dirty CarburetorThe 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 OilUsing 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 OilExcessive oil can cause pressure to build in the engine allowing oil to get into the cylinder through the valve trainDrain a little engine oil until it is at the manufacturer’s recommended oil level.
Too Little Engine OilLack of oil can increase friction in your engine causing extreme heat in the engineBring 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 FinsThe 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 CoilThe 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 DeckA 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 gasketInternal 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
Reasons a Simplicity Lawn Mower Overheats & Quits When Hot

Simplicity Mower Problem 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

CauseReason for ProblemSolution
Plugged Air FilterDirt and grass can plug the air filter preventing airflowRemove the filter and clean it. Replace the filter if it is in bad condition.
Stuck Choke or Wrong Choke SettingWhen 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 fuelFuel 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 LineA 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 FilterDirt can clog the fuel filter restricting fuel flow.Replace a plugged fuel filter.
Dirty CarburetorVarnish 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 CapWhen 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 PlugA 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 SpeedRunning 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 SpeedEngaging 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 DeckThe engine must work harder to turn blades through a deck packed with grass clippings and debris.Scrape the mower deck.
Dull Mower BladesDull blades turning through a plugged mower deck further places the engine under load.Remove and sharpen the mower blades. Balance them before reinstalling.
Reasons a Simplicity Lawn Mower is Running Rough or Sputtering

Simplicity Mower Problem 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

CauseReason for ProblemSolution
Worn Deck BeltA 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 PulleysA 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 SwitchWhen the PTO switch fails to allow the battery to energize the clutch the blades won’t turn on. Replace a bad PTO switch
Bad ClutchThe 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 & LinkagesA manual engagement clutch may not work when the clutch cable, lever, spring, or linkages are worn.Replace worn parts.
Weak BatteryA 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 SwitchWhen the seat switch doesn’t sense the operator, it won’t allow the blades to be engaged.Replace a bad battery.
Blown FuseThe 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.
Simplicity Mower Blades Won’t Engage or Turn On

Simplicity Mower Problem 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 the for a leak from a bad gas cap seal.

Detailed information can be found at:
Simplicity Lawn Mower is Leaking Gas

CauseReason for ProblemSolution
Bad Carburetor Bowl Gasket Gasket becomes dry and fails to seal allowing gas to begin leaking.Replace the carburetor bowl gasket.
Stuck Carburetor Float or Float NeedleOld gas can cause the float or float needle to stick allowing fuel to overflow.Clean the carburetor and replace any damaged parts.
Cracked Fuel LinesOld fuel lines can develop cracks.Replace an old dry fuel line.
Bad Fuel TankPoly 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 ValveA shut-off valve can develop a leak.Replace the shut-off valve.
Weak Fuel FilterFuel can degrade plastic in the fuel filter or the plastic housing can crack.Replace the fuel filter.
Bad Fuel PumpThe fuel pump can degrade and become weak at the seams.Replace the fuel pump
Bad Gas Cap SealThe seal in the gas cap can dry out and fail to seal. Replace the fuel cap.
Cracked Primer BulbThe bulb can crack or the line may be loose behind the primer bulb.Replace with a new primer bulb.
Simplicity Lawn Mower Leaking Gas Problem

Simplicity Mower Problem 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 this 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.

CauseReason for ProblemSolution
Damaged or Loose Battery Cables & WiringLoose 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 BatteryA 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 GroundThe 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 SolenoidThe 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 MotorA bad starter motor will keep the motor from starting.Replace the starter motor.
Simplicity Mower Only Clicks and Won’t Turn Over

Simplicity Mower Problem 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 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 bladeTire pressures unevenEngine speed is too low
Bent mower bladeMower deck is not levelGround speed is too fast
Blade installed wrongBlade spindle is bentDeck is damaged
Deck is plugged with dirtBad mower deck belt or pulleysOperator error
Reasons for a Bad or Uneven Cut from Your Simplicity Mower

Simplicity Mower Problem 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

CauseReason for ProblemSolution
Wrong engine oilUsing 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 levelLack 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 finsPlugged 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 placeThe engine guard shields the engine to keep air circulating around the engine to keep it cool.Securely attach the engine guard.
Plugged air filterA 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 debrisEngine work harder to turn blades through a deck full of debris.Scrape the mower deck to remove debris.
Dull mower bladesDull mower blades magnify the problem of a plugged deck.Sharpen and Balance the mower blades.
Overworking the engineCutting 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.
Reasons a Simplicity Mower is Overheating