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Home / Lawn and Garden Tractors / Husqvarna Lawn Tractors / Husqvarna YTH21K46

Husqvarna YTH21K46 Troubleshooting

The Husqvarna YTH21K46 lawn tractor was manufactured from 2012 to 2013. The components of Husqvarna YTH21K46 driveline system: a 36.4 cubic inches (597 cc) Kohler Courage SV610 4-cycle single-cylinder vertical shaft air-cooled gasoline engine with a rated power of 21 hp (15.7 kW), and Tuff Torq K46 belt-driven hydrostatic transmission with infinite forward and reverse gears.

The engine has a carburetor with fixed main jet, pulse type fuel pump, and full pressure lubrication with full-flow oil filter. The maximum forward speed - 5.2 mph (8.4 km/h), maximum reverse speed - 2.9 mph (4.7 km/h). The Husqvarna YTH21K46 is equipped with a manual steering system, disc brakes, 15x6.00-6 front tires, and 20x8.00-8 rear tires. The wheel base is 48 in (1220 mm).

The lawn tractor is compatible with a 46" mid-mount 3-blade side discharge mower deck with cutting height of 1.5-4.5" (37-115 mm), 6 cut positions, and manual lift system.

Engine Troubleshooting
Engine hard to start or won't start
Gas tank is empty - Fill fuel up
Incorrect fuel grade - Use quality fuel
Air in fuel system - Bleed fuel system
Damaged spark plug wiring connection - Inspect spark plug wiring connection, change or repair
Damaged spark plug - Change spark plug
Fuel filter is dirty - Fuel filter needs changing
Faulty safety switch - Change damaged switch
Carburetor problems - Carburetor diagnostics required
Low compression - Check and replace worn parts
Throttle cable is damaged or adjusted incorrectly - Change cable or adjust properly
Engine runs irregularly
Air intake screen is plugged - Wash or clean as required
Ignition failure - Check ignition and replace faulty components
Throttle cable is stuck or defective - Service or change the cable
Air filter element is plugged - Change or service air filter
Fuel pump is defective or dirty - Clean or change fuel pump
Engine starts but immediately shuts off
Spark plug is faulty - Replace spark plug
Clogged or faulty carburetor - Carburetor needs to be replaced or cleaned
Ignition coil is not working - Ignition coil must be replaced
Valve springs are weak or broken - Replace valve springs
Valves sticking - Valves must be cleaned
Engine is overheated
Lack of engine oil - Add oil to the engine crankcase
Engine is overloaded - Reduce the load
Cooling fins are blocked - Wash or clean as required
Too lean fuel mixture in carburetor - Use proper settings
Ignition timing is improper - Set the ignition timing correctly
Improper valve setting - Adjust valves correctly
Engine noise or knocking
Stale or low octane fuel - Use correct gasoline
Engine is overloaded - Reduce load
Engine oil level is insufficient - Fill the crankcase with engine oil
Low idle speed set incorrectly - Test and adjust
Fuel pump is clogged or faulty - Check fuel pump and replace if necessary
Worn crankshaft or main bearings - Worn parts replacement required
Valve clearance is incorrect - Adjustment procedure required
Worn cylinder bore or piston rings - Change defective parts
Engine loses power
Carburetor is clogged or incorrectly adjusted - Adjust the carburetor correctly or clean it
Air filter element is plugged - Replace or clean air filter
Fuel pump is faulty or clogged - Service or replace fuel pump
Ignition system is defective - Inspect ignition system and change faulty parts
Cylinder head gasket is blown - Replace the head gasket
Burned or stuck valves - Service or replace valves
Worn or bent push rod - Replace push rod
Faulty cylinder block components - Replace defective parts as required
Engine uses too much fuel
Choke did not open fully - Change or adjust choke cable
Carburetor main jet adjustment is incorrect - Adjust main jet as required
Spark plug is defective or loose - Re-tighten or replace spark plug
Valves are worn, burned or stuck - Replace or clean valves
Sleeve, rings, or piston are damaged - Replace defective parts
Improper valve clearance - Adjust to proper valve clearance
High oil consumption
Defective seals or gaskets - Worn parts need to be replaced
Valve guides and stems are worn - Valves replacement required
Piston rings are stuck or worn - Replace piston rings
Damaged piston or cylinder liner - Inspect liner and piston, change as necessary
Plugged breather hose or pipe - Service or change

Hydrostatic Transmission Troubleshooting
HST transmission makes excessive noise
Worn or unadjusted speed control linkage - Repair or adjust linkage
Transmission overload - The load should be reduced
Fluid is contaminated or fluid level is insufficient - Pour fresh fluid or add transmission fluid to proper level
Worn or defective parts of the hydrostatic transmission - Replace or repair defective components
Difficult to shift
Shift linkage is loose or broken - Service or change the linkage
Hydrostatic pump is seized or faulty - Change or repair pump
Defective or unadjusted transmission shift control components - Adjust properly or change
Lack of power
Transmission oil level is low - Fill up the transmission oil
Damaged or worn drive pulley - Replace pulley
Unadjusted or broken shift linkage - Replace or adjust linkage
Speed control pedal linkage is damaged or out of adjustment - Repair or adjust linkage
Transmission leakage
Transmission seals or gaskets are broken - Install new seals or gaskets
Final drive shaft leaks - Replace shaft seals
Cracked transmission case - Change broken case

Mower Deck Troubleshooting
Mower vibrates excessively
Dirty or worn mower drive sheave - Clean or replace sheave
Loose or damaged drive belt - Belt needs to be adjusted or replaced
Unbalanced or warped mower blades - Change or balance blades
Loose blade mounting bolts - Tighten it fast
Discharge chute is constantly plugged
Mowing speed is too high - Select a slower speed
Grass is too long - Adjust mower to lower cutting height
Reduced engine rpm - Adjust throttle to full opening
Cutting level is too low - Use a higher cutting height
Drive belt installed improperly - Reinstall drive belt properly
Grass patches are not cut
Mower deck is clogged - Check cutting deck and clean as necessary
Not sharp blades - Need to sharpen the blades
Blades are worn or damaged - Install new blades
Ground speed is too fast - Use a lower speed
Mower deck set to low cutting - Need to set high cutting height
Grass bag is full - Remove grass from bag
Blades scalping grass
Bumpy or not smooth lawn - Lawn leveling required
Mower deck cutting height is set too low - Use correct cutting height
Mowing speed is too high - Select a lower speed
Incorrectly leveled mower deck - Level the deck properly
Blades are worn or bent - Blades need to be replaced
Low tire inflation - Inflate tires as required
Uneven cutting
Low tire inflation - Need to inflate tires
Mower deck is not leveled properly - Deck needs to be adjusted properly
Blades are excessively dull - Need to sharpen the blades
Bent or worn blades - Blades must be changed
Deck clogged with grass clippings - Mower deck needs to be cleaned
Damaged mower deck shell - Rebuild or replace mower deck
Mower spindle is loose or defective - Repair or change the spindle

Electrical Troubleshooting
Battery is not charging
Loose or corroded cable connections - Tighten or service cable connections
Defective battery terminal clamps - Terminal clamps need to be replaced
Battery failing - Replace the battery
Starter turns slow
Low battery output voltage - Battery needs to be recharged
Battery does not hold charge - Service battery or replace it
Bad battery terminals or disconnected wiring - Connect wires properly or change terminals
Starter doesn't crank
Battery is discharged or defective - Charge or replace the battery
Battery cables are disconnected or incorrectly connected - Check cables and connect as needed
Low battery output voltage - Battery needs to be recharged
Improperly gapped or dirty spark plug - Replace or clean and gap
Solenoid or starter motor failure - Repair starter or change solenoid

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