46
Malfunction
Analysis
and
Elimination
(
I
)
Engine
malfunction
Malfunction
phenomenon
Malfunction
system
Reason
Solving
method
Starting
difficultly
or
failure
to
start
Low
compression
1.
Cylinder
worn
out
2.
Piston
worn
out
3.
Worn
or
broken
piston
rings
4.
Valve
leak
5.
Plug
is
loose
6.
Starting
motor
is
too
slow
7.
Air
circulation
is
not
right
8.
Gap
of
valve
is
incorrect
Change
Change
Change
Repair
or
change
Tighten
Check
battery
adjust
Adjust
No
ignition
generated
from
plug
1.
Dirt
on
spark
plug
2.
Wet
or
fouled
spark
plug
3.
Ignition
coil
problem
4.
Faulty
ignition
switch
5.
Magneto
problem
6.
ECU
problem
Clean
or
change
Clean,
dry
or
change
Change
Change
Change
Change
No
fuel
in
Throttle
body
1.
Vent
plugged
on
fuel
tank
2.
Plugged
injector
3.
Fuel
pump
failure
4.
Low
fuel
pressure
5.
Plugged
fuel
filter
Clean
Clean
or
change
Clean
or
change
Clean
or
change
fuel
pump
Clean
or
change
Miscellaneous
Gear
is
not
in
neutral
Put
gear
on
neutral
Erratic
idle
or
won’t
idle.
Mechanical
reasons
1.
Valve
gap
is
incorrect
2.
Worn
or
leaking
valve
3.
Blocked
exhaust
4.
Incorrect
idle
adjustment
Adjust
Repair
or
replace
Replace
Adjust
Electric
parts
problem
1.
Fouled
or
dirty
spark
plug
2.
Gap
of
plug
not
correct
3.
Ignition
switch
problem
4.
ECU
problem
5.
Magneto
problem
Clean
or
change
Change
or
adjust
Change
Change
Change
Poor
mid
to
high
rpm
performance
Mechanical
problem
1.
Weak
valve
spring
2.
Worn
camshaft
3.
Dirty
spark
plug
4.
Gap
of
plug
is
too
small.
5.
Air
circulation
is
not
right.
6.
Air
filter
is
dirty.
7.
Fuel
line
restriction
8.
Low
fuel
pressure
Change
Change
Change
or
clean
Gap
properly
Adjust
or
change
Change
Clean
or
change
Change
fuel
pump
Blue
exhaust
smoke
Mechanical
fault
1.
Oil
over
filled
2.
Piston
ring
worn
out
3.
Valve
worn
or
burned
4.
Cylinder
wall
scratched
5.
Worn
valve
seal
Drain
the
extra
oil
Change
Change
Repair
or
change
as
necessary
Change