With Normal Start, Unstable Idle Speed At Any Time - Lifan 620 Maintenance Manual

S/N
Check if the ignition sequence and timing of the
10
engine can meet with the standards.
Connect the electronic injection system adapter.
Turn on the ignition switch. Check the power supply
11
of the pin 12#, 13#, 44#, 45#, 63#. Check the
grounding of the pin 3#, 51#, 53#, 61#, 80#. Are
they OK?

6. With normal start, unstable idle speed at any time

Common trouble location:
1. Fuel with water;
4. Throttle body and idle speed by-pass air way;
6. Idle speed regulator;
8. Spark plug; 9. Mechanical part of engine.
S/N
Check the air filter for blockage and the intake air
1
way for leakage.
2 Check if the idle speed regulator is blocked.
Check the spark plug for each cylinder. Check if its
3
model and gap can meet with starndards.
Check the throttle body and idle speed by-pass air
4
way for carbon deposition.
Remove the fuel injector. Check the fuel injector for
5 leakage, blockage or abnormal flow with a special
fuel injector cleaner & analyzer.
6 Check the fuel for normal operation.
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Table 1-71 (Continued)
Operation
2. Fuel injector;
7. Ignition timing;
Diagnosis Flow
Table 1-72
Operation
93
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Test Results Actions
Yes Next step
Check and repair ignition
No
timing
Yes Diagnosis help
Check and repair relevant
No
line
3. Spark plug;
5. Intake air way;
Test Results Actions
Check and repair air
Yes
intake system
No Next step
Yes Wash and replace
No Next step
Yes Next step
No Adjust or replace
Yes Wash
No Next step
Yes Remove the trouble
No Next step
Yes Replace fuel
No Next step