Part III Fault Judgement and Repair
12
Remove the spark plug cap and the spark plug, and
install the cylinder pressure gauge at the spark
plug hole.
Pull the starter for several times and measure the
compression pressure.
Atmospheric pressure in cylinder
(≥1.25MPa/1300r)
3-1-3 Unstable speed
Phenomenon
Cause
Remedy
There is knocking
noise in the
gasoline engine
Excessive wear of piston, cylinder and piston ring
Replace worn parts
Excessive wear of piston pin and pin hole
Replace the piston or piston pin
Excessive wear of small end of connecting rod
Replace the connecting rod
Deflagration
Gasoline engine overheating
Find the cause and eliminate
There is carbon deposit in the combustion chamber. Clear carbon deposit
Unqualified gasoline
Replace with qualified gasoline
Misfire of
gasoline engine
There is water in float chamber
Clean the float chamber
Electrode clearance of spark plug is improper
Adjust electrode clearance
Ignition coil failure, etc.
Check and replace damaged parts
3-1-4 Unable to ignite
Phenomenon
Cause
Remedy
Unable to ignite
Fuel supply
system
Fuel used up
Refuel
Carburetor is clogged
Check oil way and dredge it
Fuel leakage of float chamber
Repair float needle valve
Needle valve is stuck
Disassemble the float chamber,
and remedy the trouble
Ignition system
Spark plug is broken through with
carbon deposit and short circuit
Replace the spark plug
The side electrode of the spark
plug fell off
Replace the spark plug, and
remove fallen object
Falling-off of HV wire
Replace the HV pack
Breakdown and short circuit of
ignition coil
Replace the ignition coil
Blow-out line is placed on the
body
Find short circuit point and
re-insulate
Other
Severe cylinder scraping,
falling-off of the valve
Repair and replace damaged
parts
Pressure gauge
