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IO.
TROUBLESHOOTING
The following three conditionts must be fulfilled 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)
Inferior 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 or replace the parts.
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