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Kubota GR2020 Troubleshooting

The Kubota GR2020 is a 4WD (4x4) garden tractor from GR-series. This model was manufactured between 2010 and 2019. The Kubota GR2020 powerline system components: Kubota GH630 2-cylinder air-cooled gasoline engine and hydrostatic transmission with foot travel speed control and cruise control.

A 38.1 cubic inches (624 cc) engine has a cylinder bore of 3.03" (77 mm), piston stroke of 2.64" (67 mm), and rated power of 20.5 hp (15.3 kW). Max. forward speed - 6.2 mph (10 km/h), maximum reverse speed - 3.1 mph (5 km/h). The tractor is fitted with 16x7.50-8 front tires and 23x10.50-12 rear tires.

The wheelbase is 50.4 in (1280 mm). Compatible attachments for the Kubota GR2020 garden tractor: a 48" mid-mount 3-blade mower deck with cutting height of 1.0-4.0 in (25-101) and hydraulic lift, 48" front-mount Kubota GR2707 snowblower, and 46" front-mount Kubota GR2707 blade.

Engine Troubleshooting
Engine is not starting or hard starting
Fuel tank is empty - Fill fuel up
Incorrect fuel grade - Use quality gasoline
Dirty fuel lines - Inspect and clean
Spark plug wire is loose or disconnected - Inspect the spark plug wire connection, replace or repair
Defective spark plug - Spark plug need to be replaced
Fuel filter is clogged - Replace fuel filter
Safety contact for brake pedal defective - Install new part
Carburetor is not working properly - Inspect and adjust
Low engine compression - Inspect cylinder block and change defective components
Throttle cable is damaged or adjusted incorrectly - Adjust properly or replace the cable
Unstable engine running
Air intake screen is blocked - Clean and wash as required
Ignition system is defective - Test ignition and replace failed parts
Choke cable is stuck or defective - Service or replace the cable
Air filter element is clogged - Clean or change air filter
Dirty or damaged fuel pump - Check fuel pump and replace if necessary
Engine starts and stalls suddenly
Spark plug is defective - Install new spark plug
Dirty or faulty carburetor - Service or replace carburetor
Ignition coil is defective - Install a new ignition coil
Valve springs are broken or bad - Install new valve springs
Valves sticking - Valves must be cleaned
Engine overheating
Lack of engine oil - Checking oil level and add if necessary
Engine is running overloaded - Reduce load
Plugged cooling fins - Clean and wash as required
Carburetor is running lean - Set the carburetor properly
Ignition timing is improper - Ignition timing needs to be set properly
Valve setting is improper - Set the valves correctly
Abnormal engine noise or knocking
Low octane gasoline - Use proper fuel
Engine is overloaded - Reduce load
Engine oil level is insufficient - Check oil level and add oil as required
Too low idle RPM - Adjust as required
Fuel pump is defective or dirty - Check fuel pump and replace if necessary
Main bearings or crankshaft wear - Replace crankshaft or bearings
Valve clearance is incorrect - Adjustment procedure required
Cylinder bore or piston rings are damaged - Replace defective components
Low engine power
Incorrectly adjusted or clogged carburetor - Service or properly adjust carburetor
Air filter is dirty - Replace or clean air filter
Fuel pump is dirty or defective - Check fuel pump and replace if necessary
Ignition system malfunction - Inspect ignition system and change faulty parts
Blown cylinder head gasket - Cylinder-head gasket replacement required
Valves are stuck or burned - Clean or change valves
Bent or worn push rod - Push rod needs to be changed
Cylinder block parts are faulty - Replace defective components as required
High fuel consumption
Choke is not fully open - Check choke cable and adjust it
Carburetor main jet adjustment is improper - Adjust it properly
Spark plug is loose or defective - Change or re-tighten spark plug
Stuck, burned, or worn valves - Clean or change valves
Worn rings, piston, or sleeve - Replace faulty components
Valve clearance is incorrect - Adjust valve clearance
Engine using too much oil
Gaskets or seals may be damaged - Replace defective parts
Damaged valve guides or valve stems - Valves need to be changed
Damaged or seized piston rings - Change piston rings
Damaged piston or cylinder liner - Check liner and piston, change as required
Breather hose or pipe is blocked - Clean or change

Hydrostatic Transmission Troubleshooting
HST transmission is making noise
Bent or unadjusted speed control pedal linkage - Adjust or replace linkage
Transmission is under excessive load - Load needs to be reduced
Fluid is contaminated or fluid level is insufficient - Pour fresh fluid or add transmission fluid to proper level
Transmission components are damaged or worn - Check transmission components and change if necessary
Hard shifting
Shift linkage is corroded or worn - Lubricate or replace linkage
Worn or seized hydrostatic pump - Repair or change pump
Faulty or misadjusted transmission shift control parts - Replace or adjust as required
Power is insufficient
Low oil level - Fill the transmission housing with oil
Drive pulley is worn or faulty - Change pulley
Shifter linkage is faulty or not adjusted - Change or adjust linkage
Bent or unadjusted speed control pedal linkage - Replace or adjust linkage
Transmission leaks
Transmission gaskets or seals are worn - Replace seals or gaskets
Leaking final drive shaft - Change shaft seals
Cracked transmission case - Change broken case

Mower Deck Troubleshooting
Mower vibrates too much
Clogged or damaged mower drive sheave - Clean or replace sheave
Defective or loose drive belt - Belt needs to be adjusted or replaced
Mower blades are warped or not balanced - Change or balance blades
Loose blade mounting bolts - Bolts need to be tightened
Discharge chute is constantly plugged
Ground speed is too fast - Use a lower speed
Tall grass - Need to set low cutting height
Engine runs at low revs - Adjust throttle to full opening
Cutting level is too low - Must be set to high cutting height
Improper drive belt installation - Install drive belt correctly
Uncut grass when mowing
Mower deck is clogged - Clean out the mower deck
Not sharp blades - Need a blade sharpening
Blades are defective or worn - Install new blades
Fast mowing speed - Need to slow down
Mower cuts too low - Must be set to high cutting height
Full bagger - Remove grass from bagger
Blade scalped grass
Lawn is uneven or bumpy - Roll or level the lawn
Cutting level is too low - Raise the cutting height
Fast ground speed - Use a lower speed
Mower deck is not leveled properly - Adjust mower deck level properly
Blades are bent or worn - Replace the blades
Incorrect tire pressure - Inflate tires correctly
Mower cutting is uneven
Tires are not correctly inflated - Check and inflate the tires
Mower deck is not leveled properly - Deck needs to be adjusted properly
Excessive blade dullness - Need a blade sharpening
Damaged or worn blades - Replace the blades
Cutting deck clogging - Check cutting deck and clean as necessary
Deck shell is damaged - Replace or repair the deck
Mower spindle is faulty or loose - Replace or repair the spindle

Electrical Troubleshooting
Battery cannot be charged
Corroded or loose electrical wire connections - Clean or tighten wiring connections
Defective battery terminal connectors - Replace terminal connectors
Faulty cell in battery - Use a new battery
Starter cranks slowly
Battery voltage is low - Battery needs to be recharged
Battery won’t hold charge - Service battery or replace it
Bad battery terminals or disconnected wiring - Check wiring connections and replace or clean terminals
Starter will not work
Battery is low or faulty - Battery needs to be recharged or replaced
Wire harness is disconnected or incorrectly connected - Check wire harness and connect as required
Low battery power - Recharge the battery
Improperly gapped or dirty spark plug - Clean, gap or replace spark plug
Solenoid or starter motor failure - Change solenoid or repair starter



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