IO.
TROUBLESHOOTING
The following three condit.ionts must be fulflled
for
satisfactory engine start.
1.
The cylinder filled with a proper fuel-air mixture.
2.
Good compression
in
the cylinder.
3.
Good spark, properly timed,
to
ignite the mixture.
The engine cannot be started unless these three conditions are met. There are also other factors
which
make engine start difficult, e.
g.,
a
heavy load on the engine when
it
is
about to
start
at
low speed, and a
high back pressure due to a
long
exhaust pipe.
The
most
common
causes
of
engine troubles are given below
:
10-1
STARTING
DIFFICULTIES
10-1-1
FUEL
SYSTEM
(1)
No
gasoline in
the
fuel
tank
;
or
the
fuel
cock closed.
(2)
The carburetor
is
not choked sufficiently especially when
the
engine
is
cold.
(3)
Water, dust
or
gum
in
the gasoline iterfering the fuel flow to the carburetor.
(4)
lnferior grade gasoline
or
poor quality gasoline not vaporized enough to produce the correct fuel-air
mixture.
(5)
The carburetor needle valve
is
held
open
by
dirt
or
gum. This trouble can be detected as the fuel
flows
out of the carburetor when the engine is idling. (Overflow)
This
trouble may be remedied by lightly tapping the float chamber with the grip of
a
screwdriver
or
the like.
(6)
If
the carburetor overflows, excessive fuel
runs
into
the
cylinder when starting the engine, making the
fuel-air mixture too
rich
to
burn.
If
this
happens, remove the spark plug, and
turn
the starting pulley a
few
turns
in
order to
let
the rich fuel-air mixture
out
of
the spark plug hole into the atmosphere. Keep
the choke valve open during
this
operation.
Dry
the spark plug well, screw
it
into place, and
try
to
start again.
10-1-2
COMPRESSION
SYSTEM
If
starting difficultes
and
loss
of power are
not
due to
the
fuel system
or
ignition system, the followings
must be checked for possible lack
of
compression.
Engine inside
is
completely dried up because of
a
long
period
of
storage.
Loose
or
broken
spark plug.
This
causes a hissing noise made by mixture gas running out
of
cylinder
in
compression stroke during cranking.
Damaged head gasket
or
loose cylinder head.
A
similar hissing noise is produced during compression
stroke.
Incorrect Valve clearance
If
the correct compression
is
not
obtained even after remedying the
above,
disassemble the engine
and
check further as follows
:
a)
Valve stuck open due
to
carbon
or
gum on the valve stem.
b)If
the piston rings
are
stuck
on
the piston, remove the piston and connecting
rod
from the engine.
Clean
oy
replace
the
parts.
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