1. The fuel filter is clogged. 2. Poor atomization of nozzles. 3. The plunger and cylinder of the fuel pump are worn out. 4. Deformation of the governor spring, leading to a low speed. 5. Incorrect ignition timing. 6. The air filter is clogged. 7. Gas leakage from valves. 8. Untimely operation of valves. 9. Insufficient compression ratio.
1. wash and replace the filter if necessary. 2. Adjustment or replacement of nozzles. 3. Replace with new ones. 4. Adjust or replace with a new spring. 5. Adjust. 6. Blow and clean thoroughly. 7. Check the valves for cleanliness and effective seating. 8. Valve clearance adjustment. 9. Replace the cylinder liner or piston rings.