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Kubota GR2120 Troubleshooting

The Kubota GR2120 is a two-wheel drive garden tractor from GR-series. This model was manufactured between 2010 and 2018. The Kubota GR2120 powertrain system components: Kubota D782 four cycle vertical 3-cylinder water-cooled diesel engine and shaft-drive hydrostatic transmission with a single foot pedal and standard cruise control.

A 47.5 cu.in (0.78 L) engine power rating is 18.1 hp (13.5 kW) at 3000 rev/min. The maximum forward speed - 6.2 mph (10 km/h), a maximum reverse speed - 3.1 mph (5 km/h).

The Kubota GR2120 garden tractor fitted with 16x7.50-8 front tires and 23x10.5-12 rear tires. The wheelbase is 50.4 inches (1280 mm). The tractor can be equipped with the following attachments: 48" and 54" mid-mount mower decks with cutting height of 1.0-4.0 inches (25-102 mm), 46" front-mount snow blower, and 48" front blade with manual lift.

Diesel Engine Troubleshooting
Engine won't start or starts hard
Fuel filter is dirty - Install new filter element
Closed fuel supply valve - Open supply valve to inject fuel
Water, dirt, or air in fuel system - Drain, flush, fill, and bleed system
Clogged or damaged injectors - Clean or replace fuel injectors
Damaged fuel injection pump - Replace or repair injection pump
Poor engine compression - Inspect cylinder block and change defective components
Engine stops during operation
Engine has not warmed up to required temperature - Warm up the engine as required
There is air in the fuel system - Bleed the system
Irregular fuel injection - Adjust fuel injection timing
Dirty fuel filter element - Service or replace the filter
Clogged or damaged injectors - Inspect fuel injectors and replace if necessary
Engine starts and stops
Fuel injection pump out of timing - Adjust injection timing
Fuel filter plugging - Change the filter element
Fuel injector nozzles are dirty - Change injector nozzles
Fuel injection pump is not working correctly - Rebuild or replace pump
Air cleaner element is clogged - Change or replace air cleaner element
Engine stops at idle
Incorrectly set low idle speed - Correct the settings
Defective fuel injection pump - Repair or replace injection pump
Clogged or damaged injector nozzles - Inspect injector nozzles and change if required
Valve clearance is wrong - Need to adjust valve clearance
Engine is overheated
Not enough coolant - Top up coolant. Check for coolant leaks
Cooling system parts are defective or system is dirty - Flush cooling system or replace faulty parts
Lack of engine oil - Check oil level and add oil as required
Fan belt is damaged or belt tension is incorrect - Adjust belt tension correctly or change it
Thermostat fault - Replace the thermostat
Poor engine power
Dirty or damaged injectors - Service or change fuel injectors
Incorrect fuel injection pressure - Repair or replace injection pump
Air filter element is clogged - Air filter maintenance required
Dirty oil filter element - Clean or replace engine oil filter element
Engine is running overloaded - Reduce the load or use a lower gear
Excessive valve clearance - Check and adjust as required
Incorrect low idle setting - Correct the settings
Restricted fuel hoses or pipes - Service fuel pipes and hoses
Engine compression too low: Leaking or faulty valves - Replace the valves
Engine noises or knocks
Fuel injection pump timing is incorrect - Fuel pump timing settings need to be corrected
Damaged or clogged injector nozzles - Service or replace nozzles if required
Engine oil level is insufficient - Check and refill engine oil
Coolant temperature is low - Warm up the engine
Main bearings or crankshaft failure - Crankshaft or bearings need to be replaced
Piston rings are damaged or broken - Have piston rings replaced
The flywheel to crankshaft bolts are loose - Tighten bolts as required
Engine using too much oil
Oil leakage: Damaged gaskets or seals - Replace to repair leaks
Crankcase oil too light - Fill up with the correct oil viscosity
Piston rings are seized or worn - Change the piston rings as required
Valve guides and stems are worn - Need to replace the valves
Worn cylinder liners or pistons - Inspect pistons and liners, fit new components as necessary

Hydrostatic Transmission Troubleshooting
HST transmission noises
Worn or unadjusted speed control linkage - Change or adjust linkage
Transmission overload - The load should be reduced
Dirty transmission fluid or insufficient fluid level - Top up to proper level or change transmission fluid
Transmission components are damaged or worn - Change or repair defective parts
Difficult to shift
Stuck or worn shift linkage - Linkage need to be replaced
Defective or stuck hydrostatic pump - Change or repair pump
Unadjusted or damaged transmission shift control parts - Replace or adjust as required
Power is too low
Lack of transmission fluid - Check and refill the transmission fluid
Drive pulley is damaged or worn - Install a new pulley
Shift linkage is damaged or unadjusted - Change or adjust linkage
Speed control pedal linkage is bent or not adjusted - Repair or adjust linkage
Transmission leaks
Transmission gaskets or seals are damaged - Change seals or gaskets
Final drive shaft leaks - Change shaft seals
Transmission case is cracked - Change broken case

Mower Deck Troubleshooting
Mower vibrates excessively
Mower deck drive sheave is clogged or worn - Change or clean sheave
Worn or loose drive belt - Adjust belt tension or install a new belt
Not balanced or bent mower blades - Change or balance blades
Blade bolts are not tightened well - Bolts need to be tightened
Constant clogging of discharge chute
High mowing speed - Operate at slower speed
Tall grass - Adjust mower to lower cutting height
Reduced engine rpm - Throttle is not fully open
Mower deck set to low cutting - Use a higher cutting height
Improper drive belt installation - Reinstall drive belt properly
Lawn mower leaving uncut grass
Cutting deck is clogged - Inspect and clean cutting deck
Blades are excessively dull - Sharpen the blades
Worn or damaged blades - Change the blades
High ground speed - Need to slow down
Cutting level is too low - Adjust mower to higher cutting height
Filled grass bag - Empty the grass bag
Blade scalped grass
Uneven or bumpy lawn - Roll or level the lawn
Low cutting height - Use correct cutting height
Mowing speed is too high - Operate at slower speed
Incorrect level of mower deck - Adjust mower deck level properly
Blades are bent or worn - Replace the blades
Low tire inflation - Need to inflate tires
Uneven cutting
Tire pressure is too low - Inflate tires correctly
Deck level is not correct - Adjust the level of mower deck correctly
Blades are too dull - Sharpen the blades
Bent or worn blades - Install new blades
Discharge chute is plugged - Clean out the mower deck
Deck shell is broken - Replace or repair the deck
Loose or defective mower spindle - Install new spindle or repair it

Electrical Troubleshooting
Battery will not charge
Loose or corroded wire connections - Service or tighten connections
Defective battery terminal clamps - Change terminal clamps
Defective battery - Battery replacement required
Starter cranks slow
Battery voltage is low - Battery is drained, charge it
Battery is draining quickly - Service or replace the battery
Bad terminals or disconnected battery cables - Check wiring connections and replace or clean terminals
Starter will not work
Battery is discharged or worn - Recharge or replace battery
Wire harness is disconnected or incorrectly connected - Check wire harness and connect as required
Low battery capacity - Battery needs to be recharged
Faulty or incorrectly gapped spark plug - Clean, gap or change spark plug
Starter motor or solenoid is defective - Starter/solenoid needs to be replaced



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