Yingang YG125-23, Maintenance Manual

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YG125-23 Maintenance ManualEngine management system
154
Maintenance depending on the performance.
Before issue analysis, please check:
1) The MIL works well.
2) Clear the history malfcode.
3) When the malfcode comes again, note the condictions.
Check the appearance
1) Whether there is leakage of the fuel pipe or not.
2) Whether there is block/leakage or damage of the intake pipe.
3) Ageing level of the high-voltage cable.
4) Whether the ground connection is strong enough.
5) All the connectors connected well.
Note: if any item above exists, please do the fix it at first before issue analysis.
Diagnostic Help
：
1) Make sure there is no any issue record of the engine.
2) Make sure the issue could repeat.
3) Have checked follow the instructions above and no cause found.
4) Do not ignore the maintenance situation, cylinder pressure, mechanical timing and fuel quality.
5) Change the ECU and repeat the test, if the issue is gone, then the root cause is the ECU. Or change the old one
back to check the root cause.
ITEM OPERATION RESULT NEXT STEP
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Check whether the voltage of the battery is around 8-12V.
Yes Next
No Change the battery.
Crank the engine, and check whether the voltage is above 8V.
Yes Next
No Change the battery.
Check whether the start motor working well or not.
Yes Next
No Change the start motor.
If the issue only occurs in winter, check the oil and gear box oil.
Yes Change the oil
No Next
Check whether the engine rotation resistance is too big or not.
Yes Check the enigne
No Help
Check wether the fuel pump pressure is about 250kPa at idle.
Yes Next
No Check the pump.
Check whether the
‘RMP’ data on the diagnostic tool shows the
real engine RPM.
Yes Next
No Check the crank sensor.
Pull out the spark plug, check whether the spark over is normal.
Yes Next
No Check the ignition system
Check whether the cylinder pressure is normal.
Yes Engine is good.
No Check the engine