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Craftsman YT-4000 Troubleshooting

The Craftsman YT4000 lawn tractor was manufactured by Husqvarna built from 2009 to 2013. The Craftsman YT 4000 tractor is powered by Briggs and Stratton 445677 4-cycle V-twin cylinder OHV air-cooled gasoline engine. A 44.2 cubic inches (724 cc) engine has a cylinder bore of 3.12" (79 mm), piston stroke of 2.89" (73 mm), and rated power of 24 hp (17.8 kW) at 3400 rpm.

The Craftsman YT4000 is fitted with 3 transmission options: mechanical transmission with 6 forward and 1 reverse gears, Tuff Torq K46 belt-driven hydrostatic transmission with foot-controlled variable speed drive, and Hydro Gear hydrostatic transmission with infinite forward and reverse gears. The maximum travel speed (forward/reverse): 5.4 mph (8.7 km/h) and 2.9 mph (4.7 km/h).

The Craftsman YT4000 was equipped with a manual steering, disc brakes, 15x6.00-6 front tires, and 20x8.00-8 or 18x9.50-8 rear tires. The tractor is compatible with 42" or 46" mid-mount 2-blade mower deck with cutting height of 1.0-4.0 in (25-100 mm), six cut positions, and manual lift system.

Engine Troubleshooting
Engine is not starting or hard starting
Empty fuel tank - Add fuel
Low-quality gasoline - Use correct fuel grade
Air or water in fuel system - Remove water or air from fuel system
Loose or disconnected spark plug wire - Inspect the spark plug wire connection, replace or repair
Spark plug is damaged - Spark plug need to be replaced
Dirty fuel filter - Install new filter
Defective safety switch - Replace if required
Incorrect carburetor adjustment - Adjust carburetor idle mixture screw
Poor compression - Inspect and replace wear parts
Incorrectly adjusted or damaged throttle cable - Change cable or adjust properly
Engine runs intermittently
Cooling fins are plugged - Need to clean or wash
Ignition system failure - Test ignition and replace failed parts
Stuck or defective throttle cable - Service or replace the cable
Dirty air filter element - Replace or service air filter
Fuel pump is damaged or dirty - Service or change fuel pump
Engine starts and stops
Faulty spark plug - Install new spark plug
Faulty or dirty carburetor - Replace or service carburetor
Ignition coil is faulty - Replace ignition coil as necessary
Broken or loose valve springs - Change valve springs
Stuck valves - Clean the valves
Engine overheating
Engine oil level is low - Need to add engine oil
Engine is under excessive load - Reduce load
Air intake screen is plugged - Need to clean or wash
Carburetor is running lean - Set the carburetor correctly
Incorrect ignition timing - Ignition timing needs to be adjusted correctly
Valve setting is improper - Valves needs to be set correctly
Abnormal engine noise or knocking
Stale fuel - Use correct gasoline
Excessive engine load - Reduce the load
Engine oil level low - Need to add engine oil
Low idle speed set incorrectly - Correct the settings
Fuel pump is faulty or clogged - Clean or change fuel pump
Worn crankshaft or main bearings - Crankshaft or bearings need to be replaced
Valve clearance is improper - Adjustment procedure required
Cylinder bore or piston rings are damaged - Replace defective components
Low engine power
Carburetor is incorrectly adjusted or dirty - Adjust the carburetor properly or clean it
Air filter element is plugged - Replace or clean air filter
Fuel pump is faulty or clogged - Test fuel pump and change if necessary
Ignition system problems - Inspect ignition system and change faulty parts
Cylinder head gasket is worn - Install new head gasket
Valves are burned or stuck - Service or change valves
Push rod is worn or defective - Push rod needs to be changed
Faulty cylinder block components - Change defective components
Engine using too much gasoline
Throttle not fully open - Check throttle cable and adjust as required
Improper adjustment of carburetor main jet - Adjust it properly
Spark plug is loose or defective - Re-tighten or replace spark plug
Worn, stuck, or burned valves - Replace or clean valves
Sleeve, piston, or rings are damaged - Change defective parts
Valve clearance is wrong - Need to adjust valve clearance
Excessive engine oil consumption
Defective seals or gaskets - Replace defective parts
Damaged valve stems or valve guides - Change the valves
Piston rings are seized or worn - Replace piston rings
Scored piston or cylinder liner - Inspect piston and liner, fit new components as necessary
Breather pipe or hose is blocked - Change or service

Transmission Troubleshooting
Hard shifts
Worn or rusty gear shift linkage - Install new shift linkage
Shift forks are damaged or worn - Replace the shift forks
Gearshift mechanism is damaged - Replace or repair the mechanism
Transmission is excessively noisy
Low oil level - Check transmission oil level and add oil as required
Transmission fluid is contaminated - Fill up with new transmission fluid
Worn bearings or damaged gears - Change bearings or gears
Transmission jumps out of gear
Shift lever is damaged or installed improperly - Replace or install shift lever correctly
Gears are damaged or worn - Replace defective gears
Faulty shift rods or shift forks - Change defective forks or rods
Transmission slipping
Drive shaft/belt is improperly adjusted or damaged - Adjust or change belt/shaft
Clutch/brake is defective or improperly adjusted - Change clutch/brake or adjust it
Faulty or worn drive sheave - Replace sheave

Hydrostatic Transmission Troubleshooting
HST transmission is excessively noisy
Speed control linkage is worn or unadjusted - Adjust or repair linkage
Transmission overloaded - Reduce transmission load
Oil is dirty or oil level is too low - Add oil to the correct level or fill the transmission with fresh oil
Transmission parts are worm or defective - Replace or repair defective components
Hard shifting
Shift linkage is stuck or damaged - Clean or change linkage
Hydrostatic pump is faulty or seized - Change or repair pump
Transmission shift control parts are faulty or unadjusted - Adjust correctly or replace
Power is too low
Insufficient transmission fluid - Need to add transmission fluid
Faulty or worn drive sheave - Install a new sheave
Shifting linkage is misadjusted or broken - Replace or adjust linkage
Worn or unadjusted speed control linkage - Repair or adjust linkage
Transmission leaking
Damaged transmission seals or gaskets - Replace gaskets or seals
Leaking final drive shaft - Install new shaft seals
Transmission case is cracked - Change broken case

Mower Deck Troubleshooting
Mower vibrates too much
Drive sheave of mower deck is dirty or worn - Replace or service sheave
Damaged or loose drive belt - Change belt or adjust belt tension
Mower blades are warped or not balanced - Balance or replace blades
Blade bolts are not tightened well - Tighten bolts as required
Discharge chute regular clogging
Fast ground speed - Use a slower speed
Long grass - Adjust mower to lower cutting height
Engine rpm is too low - Adjust choke to full opening
Mower deck set to low cutting - Change cutting height adjustment
Drive belt installation is not correct - Install drive belt correctly
Lawn mower leaving uncut grass
Mower deck is clogged - Clean mower deck as required
Blades are not sharp - Blades need to be sharpened
Worn or damaged blades - Install new blades
Fast mowing speed - Use a slower speed
Low cutting height - Must be set to high cutting height
Full grass bag - Clean grass bag
Blades scalp the grass
Bumpy or not smooth lawn - Roll or level the lawn
Cutting level is too low - Adjust mower to higher cutting height
High ground speed - Use a lower speed
Mower deck is not leveled properly - Adjust mower deck level properly
Bent or worn blades - Replace the blades
Low tire inflation - Correct tire pressure
Mower deck to cut unevenly
Tires are not correctly inflated - Inflate tires as required
Deck level is not correct - Deck needs to be adjusted properly
Excessive blade dullness - Need a blade sharpening
Worn or bent blades - Blades must be changed
Discharge chute is plugged - Need to clean the mower deck
Deck housing is broken - Repair or change the deck
Mower spindle is bent or loose - Repair or change the spindle

Electrical Troubleshooting
Battery is not charging
Corroded or loose cable connections - Tighten or service connections
Battery terminal clamps are defective - Change terminal clamps
Defective battery - Battery change required
Starter turning slow
Battery power is low - Battery is drained, charge it
Battery does not hold charge - Service charging system or install new battery
Disconnected battery cables or bad terminals - Connect cables correctly or replace terminals
Starter doesn't crank
Battery is discharged or defective - Recharge or replace battery
Wire harness is disconnected or incorrectly connected - Check wire harness and connect as required
Battery capacity is low - Battery is drained, recharge it
Improperly gapped or dirty spark plug - Clean and gap or replace
Starter motor or solenoid failing - Starter/solenoid needs to be replaced



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