Yingang YG125-25, Maintenance Manual

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YG125-25 Maintenance Manual Engine management system
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
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Check wether the fuel pump pressure is about 250kPa at idle.
Yes Next
No Check the pump.
Pull out the spark plug, check whether the sparkover is normal.
Yes Next
No Check the ignition system
Remove the connector of the engine temperature sensor, and
check whether the enigne start well.
Yes
Check the engine
temperature sensor
No Next
With a little bigger throttle, check wheterh the engine starts well.
Yes
Clean the throttle body and
bypass channel.
No Next
Pull out the injector, and crank the engine. Check whether the
injection is normal.
Yes Next
No
Clean or change the
injector.
Pull out the sprk plug, check whether it is wet or not
Yes
dry the plug and
combustion chamber.
No Next
Check whether the cylinder pressure is normal or not
Yes Engine is good
No Check the engine
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Check whether the air filter is blocked and whether the intake
pipe leaks.
Yes Intake system maintenance
No Next
Whether there is carbon deposit at the throttle body and bypass
channel.
Yes Clean the TB
No Next
Check whether the IACV works well Yes Next
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