Service manual

Information Summary and Preparation 1
16
(6) Start-up normal but idle speed unstable anytime
General trouble location: 1. Water in fuel; 2. Nozzle; 3. Spark plug; 4. Air throttle and idle air bypass;
5.Air intake; 6. Idle governor; 7. Ignition timing; 8. Spark plug; 9. Engine mechanism.
Procedure for general diagnoses:
No. Operating Procedure
Detection
Results
Subsequent Steps
1 Check any jam of the air filter and leakage of the air intake.
Yes
Repair the air intake
system.
No Next step
2 Check the Idle governor for the control valve jammed.
Yes Change
No Next step
3
Check the spark plug and its model and gap conformable to
specifications.
Yes Next step
No Adjustment or change
4
Check the air throttle and the idle air bypass for any carbon
deposition.
Yes Cleaning
No Next step
5
Disassemble the nozzle and check any leakage or jam in the
nozzle with a nozzle cleaner & analyzer.
Yes
Replace the defective
nozzle.
No Next step
6 Check fuel and observe any trouble attributed to fuel just added.
Yes Change fuel.
No Next step
7
Check pressure of the engine cylinder and find any big difference
in pressure.
Yes
Eliminate any
mechanical trouble of the
engine.
No Next step
8
Check if mechanical ignition timing of the engine is conformable
to specifications.
Yes Next step
No Correct ignition timing.
9
Connect an EMS adapter and press the power switch to check
voltages at Pins 5#, 10#, and 23#; check grounding at Pins 2# and
21#.
Yes Diagnosis assist
No
Repair the relevant
circuits.