IO.
TROUBLESHOOTING
a
The following three conditions 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 interfering the fuel flow to the Carburetor.
(4)
Inferior grade gasoline or poor quality gasoline is 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, depending
on
cases, 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 carburetor choke 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 difficulties and loss of power are not due to the fuel system or ignition system, the
following must be checked for possible lack of compression.
(1)
Engine inside is completely dried up because
of
a
long period
of
storage.
(2)
Loose or broken spark plug. This causes a hissing noise made by mixture gas running out
of
(3)
Damaged head gasket or loose cylinder head.
A
similar hissing noise
is
produced during compres-
(4)
Incorrect valve clearance
cylinder in compression stroke during cranking.
sion stroke.
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.
-51
-
To Next Page
Loading...
