Fault Diagnosis
Symptom: Engine will not start or is hard to start
Diagnosis procedures
Perform spark-over test
Clean deposited carbon
Spark is weak between electrodes or no spark at all. Strong blue or violet spark leaps between electrodes
Engine will not start or is hard to start
Check ignition system
Remove the spark plug and check if electrodes of the plus are connected by carbon.
Screw off spark plug cap, perform high-voltage wire spark over test Use an ignition timing lamp to check ignition timing of engine
Strong blue spark leaps Weak or no spark
Check spark plug and cap
1. Check CDI igniter 2.
Check if magneto
flywheel or trigger coil
looses.
Loosen drain screw of
carburetor and check
if there is oil flowing
out from overflow pipe
Refuel
gasoline
Check compression
pressure in the
cylinder.
Check oil in
the fuel
tank.
Compression
pressure in
the cylinder
is normal.
Check ignition
power
supply.
Check if wires in
the ignition system
are shorted or
broken.
Check if
CDI igniter
fails.
Non-contact battery ignition system Non-contact magneto ignition system
1. Check electric quantity
of battery; 2.Check if
low-voltage circuit is
broken or shorted; 3
Check if trigger coil is
shorted or broken.
1. Check if ignition
power supply coil is
shortened or broken; 2.
Check if trigger coil is
shorted or broken.
Compression
pressure in
the cylinder
is low.
No Yes
No Yes
Yes No
Yes
No
Check if
ignition coil is
shorted or
broken.
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