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Common Zero Turn Problems: How to Fix Them

Owning a zero turn lawn mower doesn’t come without its problems. Owners must accept the fact that some item on their zero turn will fail after time. With a good maintenance routine, you can prevent some of these problems. However, if you own the same zero turn long enough, components will eventually begin to wear and fail.  

Some of the most common zero turn problems and owner complaints are: 

  • Zero turn won’t start
  • Zero turn dies while mowing
  • Zero turn is smoking
  • Zero turn has a weak hydrostatic transmission
  • Zero turn won’t drive straight or steer correctly
  • Zero turn won’t move
  • Zero turn is shaking or vibrating
  • Zero turn is cutting uneven
  • Zero turn is leaking gas
How to fix common zero turn mower problems

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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, knowledge or are not in the condition to perform the repair safely.

Zero Turn Lawn Mower Problems 

Zero Turn Mower Won’t Start

Your zero turn lawn mower may not start because of fuel system problems such as a bad fuel, dirty carburetor, or a bad fuel pump. A bad spark plug, battery, safety switch and ignition switch can also cause your zero turn not to start.  

Detailed information can be found at:
Why Your Zero Turn Won’t Start

CauseReason for ProblemSolution
No gas in the fuel tankFuel 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 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 air flowRemove 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 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 carb cleaner and compressed air to clear the clog out of the fuel line. Replace line if necessary.
Dirty carburetorThe carburetor can become dirty and clogged due to bad fuel and ethanol deposits preventing fuel flowClean the components making up the carburetor. Replace if needed.
Bad battery or loose & dirty terminalsA dead battery, loose cables or corroded terminals can cause starting problemsCharge your battery and replace if it won’t hold a charge. Make sure your cables are tight and clean the corrosion from terminals.
Bad safety switchSafety switches is a safety measure that exist 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 coilYour mower will not start when either the ignition switch or coil is badTest and replace a bad switch
Bad charging systemA charging system that can’t keep your mower charged and is constantly draining the battery must be repaired to prevent starting problems.Take your lawn mower to your local dealer or mechanic for assistance identifying which part of the charging system has failed.
Reasons Your Zero Turn Mower Won’t Start

Zero Turn Mower Starts Then Dies

Some of the same items that cause your zero turn to not start are also items that can cause your mower to die while mowing. When your mower can’t get enough air and fuel it will shut down. You could have a clog that moved through your fuel system or your air filter is blocking air.

An issue that can present itself after mowing for a little while is a bad fuel cap that doesn’t allow air to pass through the cap’s vent. A plugged cap causes your fuel tank to form a vacuum so fuel is unable to flow out of the tank.

When your engine overheats, your mower can shut down. Inspect your cooling fins to ensure they are not broke or plugged with dirt. The fins keep air movement around your engine block and cylinder head.

Detailed information can be found at:
Zero Turn Mower 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 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 air flowRemove 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
Dirty carburetorThe carburetor can become dirty and clogged due to bad fuel and ethanol deposits preventing fuel flowClean the components making up the carburetor. Replace if needed.
Reasons Your Zero Turn Mower Dies While Mowing

Zero Turn Lawn Mower Smokes 

It can be quite alarming when you see smoke emitting from your zero turn mower. A plugged air filter, wrong engine oil level or other internal engine problems can cause smoking. When your engine doesn’t receive the correct air to fuel ratio or oil becomes hot and burns off, your zero turn will begin to smoke.

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 air flowRemove 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 manufacturers recommended oil level.
Engine oil level is too lowLack 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 to have this fix your engine problem.
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 zero turn to your local dealer or small engine repair shop for troubleshooting
Reasons Your Zero Turn Mower is Smoking

Zero Turn Mower Has a Weak Hydrostatic Transmission 

Zero turn mowers have intervals when you must change your hydraulic fluid for best performance. When you run a low level of hydro oil or your oil is getting aged, you can develop transmission problems. Your zero turn’s transmission may seem weak. Weakness can also be caused by a bad drive belt or tensioner pulley.

CauseReason for ProblemSolution
Bad drive beltA bad drive belt can cause your pump not to work efficientlyReplace a frayed, cracked 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 regularly intervals as recommended by your zero turn manufacturer.
Check your hydraulic oil periodically to ensure your hydraulic fluid is full.
Reasons Your Zero Turn Mower’s Hydrostatic Transmission Seems Weak

Zero Turn Mower Won’t Drive Straight or Steer Correctly

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 manufacturers spec. Tires on each side of your mower requires equal pressures.
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 turn or standon mowerWhen one tire is moving faster than the other, your mower can pull to one sideAdjust speed adjustment bolt to change the rotation speed of the tire. Refer to your owner’s manual.
Reasons Why Your Zero Turn Won’t Drive Straight or Steer Correctly

Zero Turn Lawn Mower Won’t Move

Old hydraulic oil or an insufficient oil level can also cause your zero turn to not move or, if it does, it may move slowly. Check the drive belt, tensioner pulley and spring. If any of these items are worn or missing, your zero turn mower may not move.

Another item to check is the hydraulic release lever. You may have recently had to manually move your mower and used the drive release lever to release the hydros. Make sure your drive release levers are in the operating position. If they are not, your mower will not move.

Detailed information can be found at:
Zero Turn Mower Won’t Move or Go Forward

CauseReason for ProblemSolution
Drive release lever in the wrong positionThe drive release lever allows hydrostatic mowers to roll freelyThe drive release lever must be in the operating position.
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 or cracked 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 regularly intervals as recommended by your zero turn manufacturer.
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 does becomes weak when the hydraulic system gets hot, have your mower checked at your local zero turn dealership or repair shop.
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 the zero turn manufacturer procedures for changing hydraulic fluid and bleeding air from the system in your owner’s manual.
Reasons Why Your Zero Turn Will Not Move or Go Forward

Zero Turn Mower is Vibrating

There is always some vibration that comes from running the engine. However, there are times when you may feel a severe vibration that isn’t the typical vibration. This is something that needs to be addressed to minimize mower damage.

There are many things you need to check including engine mounting bolts, debris caught in the mower deck and worn or damaged components.

Detailed information can be found at:
Your Zero Turn is Shaking & Vibrating

CauseReason for ProblemSolution
Loose or missing engine mounting boltsEngine bolts are used to reduce vibration of the mower when the engine is runningSecure engine bolts and replace any missing bolts
Clutch is badWhen 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 bladesDamaged and unbalanced blades can send a vibration through your mower. Blades must be balanced before installingReplace any damaged blades and make sure they are balanced.
Material wrapped around the blade spindleForeign 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 bearingsVibration can be caused by a bad bearing in the spindle housing.Replace bearing in the spindle housing or replace the whole spindle housing assembly
Worn pulleys or deck beltCheck deck belt and pulleys for wearing of the belt and bearing failure in the pulleysReplace any damaged or worn belts and pulleys
Debris lodged in mowerThe smallest little things can cause your zero turn 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.
Reasons Your Zero Turn Mower is Vibrating

Zero Turn Mower Has a Bad or Uneven Cut

When your cut is uneven or just bad, you need to fix it so you can continue to have a great looking lawn. There are many items that can affect cut including low tire pressures, worn deck components, clogged mower deck and incorrect operating procedures.

Detailed information can be found at:
Your Zero Turn Lawn Mower is Cutting Uneven

Worn mower bladeUneven tire pressuresEngine speed is too low
Bent mower bladeUnleveled mower deckGround speed is too fast
Blade installed wrongBent blade spindle or spindle bearingDamaged deck shell
Clogged Mower DeckWorn deck pulleys or beltOperator error
Reasons Your Zero Turn Mower is Cutting Uneven

Zero Turn Mower is Leaking Gas

When you smell a strong odor or see spots of burnt grass in your yard, you need to follow your fuel lines out of the fuel tank to find a fuel leak. Leaks can be hard to find because fuel often evaporates and you’re left only with smelling gas fumes.

A common area where zero turns develop leaks is in the carburetor. The gasket around the carburetor bowl can become dry losing its sealing ability or the float can become stuck.

Old gas can also cause plastics to degrade in your components developing leaks in your fuel filter, fuel pump or fuel tank seams.

Detailed information can be found at:
Your Zero Turn Mower is Leaking Fuel

CauseReason for ProblemSolution
Dirty of Failed CarburetorThe carburetor can collect a buildup of substances remaining from old gas that can cause blockages or parts failuresClean the carburetor and replace any damaged parts
Old Fuel FilterFilter can become pluggedReplace fuel filter
Bad Fuel PumpPump can wear and deteriorate over time and may begin leaking at the seamsReplace the fuel pump
Bad Fuel TankA metal tank can develop a rust hole. A poly tank can leak at the seams of the tank.Replace the fuel tank. Sometimes, a rust hole can be repaired if you can no longer find a replacement tank.
Bad Fuel Shut-Off ValveMetal and plastic shut-off valves are prone to leakingReplace the shut-off valve
Cracked Fuel LinesRubber fuel lines become dry and cracked causing gas to leakReplace the fuel lines
Bad Seal in the Gas CapThe gas cap seal can fail and no longer seal allowing gas to splash out of the fuel tank around the gas capReplace the gas cap
Where Your Zero Turn Mower May Be Leaking Gas

Perform Regular Maintenance on Your Zero Turn

Taking time to check your mower before each mowing and performing routine service on your zero turn will prevent some of these issues or allow you to catch the problems before they develop into costly repairs. See my article on servicing your zero turn for a list of items you need to check when performing routine maintenance.