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Kubota D722 Troubleshooting

Engine Model: Kubota D722
Engine Type: 4-cycle 3-cylinder liquid-cooled diesel engine
Total Displacement: 43.9 (0.72 L)
Rated Engine Power: 20.0 Hp (14.9 kW) at 3800 rpm
Aspiration Type: Naturally aspirated


Engine difficult to start or will not start

Fuel filter element is clogged - Service or replace the filter.
Air in fuel tank - Bleed fuel tank.
Fuel injection nozzles are faulty or clogged - If necessary, replace with a new nozzle.
Fuel injection pump is damaged - Install a new fuel pump or repair.

Diesel starts but stalls suddenly

Fuel filter element is clogged - Clean or replace the filter.
Fuel injection pump malfunction - Repair or change injection pump.
Clogged air filter - Carry out maintenance on air filter.

Engine shuts off suddenly during operation

Fuel injection pump timing is wrong - Set up as recommended.
Fuel filter element is clogged - Filter maintenance required.
Engine is not preheated - Engine is not warmed up to the required temperature.

Engine stalls at idle

Low idle speed set incorrectly - Need to adjust idle speed.
Improper valve clearance - Adjust valve clearance.
Fuel injection pump is broken - Rebuild or install a new injection pump.

Lack of engine power

Fuel injection nozzles are damaged or dirty - Service or change injection nozzles.
Fuel lines or hoses are dirty - Fuel hoses and lines must be clean.
Air filter is dirty - Change air filter element.
Blown cylinder head gasket - Install new cylinder head gasket.

Engine overheating

Faulty radiator cap or dirty radiator fins - Change cap or clean radiator.
Not enough coolant - Add coolant and check the components of cooling system.
Excessive wear of the fan belt - Install new fan belt.
Engine oil insufficient - Fill up the oil to required level.

Oil pressure is low

Lack of oil - Add oil to the engine crankcase.
Oil pump malfunction - Repair or change.
Oil filter is clogged - Change or service engine oil filter.

Engine consuming too much oil

External oil leaks: Damaged seals or gaskets - Replace worn parts to avoid leaks.
Crankcase oil too light - Fill up with the correct oil viscosity.
Worn or stuck piston rings - Change the piston rings as required.
Damaged valve stems or valve guides - Replace the valves.
Cylinder liners or pistons are scored - Check pistons and liners, replace as required.

Abnormal engine noise or knocking

Engine is not warmed up to the required temperature - Warm up engine as required.
Not enough engine oil - Need to add engine oil.
Improper fuel injection timing - Adjust fuel injection pump as required.
Pistons are broken or worn - Install new pistons.
Connecting rod misalignment or failure - Align or replace connecting rod.

Starter turns slow

Low battery power - Recharge the battery.
Battery discharges quickly - Service charging system or install new battery.
Bad battery terminals or disconnected wiring - Check cables and clean or change terminals.

Starter does not work

Battery is drained or defective - Need to charge or replace the battery.
Battery wiring is disconnected or improperly connected - Inspect wiring and connect as required.
Low battery voltage - Battery is drained, recharge it.
Starter motor failing - Starter needs to be changed.