33 

 

No. 019 Engine vibration   

Malfunction Cause 

Solution 

Engine bracket or vehicle body deformed 

Replace engine bracket or correct vehicle body. 

Low fuel pressure 

Check supply pressure of fuel system, whether it is too 
low, while the normal value is between 250kPa and 
300kPa. Replace fuel pressure controller, fuel filter or 
electric fuel pump and other relevant damaged 
components.   

Clutch system malfunction 

Generally, the malfunction is caused by unbalance fly 
wheel or press plate etc. Replace relevant components. 

Engine operating with unavailable cylinder 

Spark plug, cylinder cable, valve, valve clearance, 
injector and cylinder sleeve worn out, and results 
unavailable cylinder. Exclude the malfunction. 

Check idle speed stepping motor, whether it is too much 
carbon deposit. Clean or replace it when necessary. 

Electric injection unit malfunction 

Check throttle opening degree, clean or replace throttle 
sensor when necessary. 

Engine 
operating 
unstably, 
starting 
slowly, with 
surge and 
vibration 

ECU damaged 

Check ECU integrated circuit, whether it is damaged. 
Replace it when necessary. 

 

 

Engine vibration 

Engine oprating with unavailable cylinder 

Low fuel pressure 

Engine bracket or vehicle body deformed 

Clutch system malfunction 

ECU damaged 

Check 

Check and replace 

Replace 

Check and replace 

Check 

Normal 

Normal 

Normal 

Normal 

Damage 

Abnormal 

Deform 

Low 

Check 

 
 

 

 

34 

 

No. 020 Exhaust pipe pours black smoke   

Malfunction Cause 

Solution 

Air filter blocked 

Check and clean/replace air filter 

Low fuel quality 

Apply unleaded clean fuel, 93# or above, which is in accordance 
with manufacturer requirements. 

Fuel contains in vacuum pipe 

Check fuel pressure controller, whether it is damaged and leaking

High oil pressure 

Check fuel pump, pumping pressure and controller function. 

Improper ignition timing 

Check and adjust ignition timing 

Unavailable cylinder 

Implement cylinder cross firing test respectively, check the 
performance of wire and spark plug. 

Valve leaking 

Clean combustion chamber carbon deposit. Replace or grind 
valve. 

Injector leak or atomization abnormal 

Clean or replace malfunction injector 

Throttle position sensor malfunction 

Measure the resistance and voltage of throttle, replace it when 
necessary. 

Oxygen sensor voltage abnormal 

Measure sensor voltage and resistance, replace it when 
necessary. 

Cylinder gasket damage 

Maintain or replace cylinder gasket. 

ECU malfunction 

Check ECU and circuit whether they are normal. 

Light smoke 
when idling, 
heavier when 
accelerating 

Low cylinder pressure 

Disassemble and maintain engine. 

 
 

 

 

35 

 

Exhaust pipe pours black smoke 

Air filter blocked 

Low fuel quality 

High oil pressure 

Unavailable cylinder 

Improper ignition timing 

Oxygen sensor voltage abnormal 

Valve leaking 

Cylinder gasket damage 

ECU failure 

Injector leak or atomization abnormal 

Low cylinder pressure 

Check 

Clean or replace 

Replace 

Check and replace 

Check 

Check and replace 

Check and replace 

Replace 

Replace 

Clean or replace 

Adjust 

Abnormal 

Low 

Blocked 

Abnormal 

Abnormal 

Abnormal 

Leaking 

Abnormal 

Abnormal 

Abnormal 

Abnormal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

 
 

 

 

36 

 

No. 021 Engine idle speed decreases when activating head beam or fan   

Malfunction Cause 

Solution 

Fuel quality is not in 
accordance with requirement 

Apply unleaded clean fuel, 93# or above. 

Generator belt loose 

Adjust belt tension to 50NM, when pressuring downwards, and the 
deflection shall be 10MM. 

Earth lead loose 

Check gearbox, body earth lead and instrument earth lead, whether 
they are loose. Tighten them when necessary. 

Generator operates abnormal 

Check the electrical energy of generator, whether it is beneath 9V. 
Replace generator voltage controller when necessary. 

Battery open circuit 

Check the gravity of battery electrolyte, maintain or replace battery 
assembly when necessary. 

Idle speed controlling valve or 
stepping motor malfunction 

Clean idle speed control valve or stepping motor. Replace it when 
damaged. 

Grouped switch short circuit 

Maintain grouped switch and relevant harness. 

The power of head beam or the 
load of fan is over normal value.

Check head beam, whether it applies the bulb requires the power over 
standard value. Replace standard power bulb when necessary. 
Replace fan motor or maintain the circuit. 

Low generator charging current 
(75A) 

Replace generator assembly, which supplies 90A charging current. 

Poor ECU signal 

Measure the voltage among terminals and wire connecting condition. 
Maintain or replace them when necessary. 

Engine speed 
decreases, with 
vibration, when 
activating head 
beam or fan 

Engine operates abnormal 

Maintain engine