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PART 9-1-
GENERAL
IGN ITION SYSTEM
SERVICE
IDENTIFIED
BY
BLACK
.
DRY FLUFFY CARBON
DEPOSITS ON INSULATOR
TIPS, EXPOSED SHELL
SURFACES
AND ELECTRQDES.
CAUSED BY TOO COLD A
PLUG
,
WEAK IGNITION
,
DIRTY
AIR
CLEANER, DEFECTIVE fUEL
PUMP, TOO RICH A FUEL
MIXTURE
,
IMPROPERLY
OPERATING HEAT RISER
OR EXCESSIVE IDLING.
CAN BE CLEANED.
IDENTIFIED
BY DARK
GRAY
,
BLACK
,
YELLOW
OR
TAN DEPOSITS OR A
FUSED GLAZED COATING
ON THE INSULATOR TIP
.
CAUSED BY
HIGHLY
LEADED GASOLINE. CAN
BE CLEANED.
IDtNTifiED [)) MELTEC
OR SPOTTY DEPOSITS
RESEMBLING
BUBBLES
OR
BLISTERS.
CAUSED BY SUDDEN
ACCE LE RAT
ION
.
CAN
BE
CLEANED.
IDENTIFIED BY
WET BLACK DEP.
OS ITS ON
THE INSULA TOR
SHELL
BORE ELECTRODES CAUSED BY
EXCESSIVE
OIL
ENTERING COM BUS.
TION
CHAMBER
THROUGH WORN
RINGS
AND
PISTONS, EXCESSIVE
CLEARANCE
BETWEEN
VALVE
GUIDES
AND STEMS,
OR WORN
OR
LOOSE BEARINGS. CAN BE CLEANED
IF ENGINE IS NOT
REPAIRED,
USE
A HOTTER PLUG.
IDENTIFIED BY
LIGHT
TAN
OR
GRAY DE POSITS ON THE
FIRING TIP
CAN tlE CLEANED.
IDENTIFIED BY A WHITE UR LIGHT
GRAY
INSULATOR
WITH
SMALL
BLACK OR GRAY BROWN
SPOTS
AND WITH BLUISH-BURNT, APPEAR.
ANCE OF ELECTRODES, CAUSED
BY ENGINE OVERHEATING. WRONG
TYPE OF
FUEL, LOOSE
SPARK
PLUGS,
TOO HOT A PLUG, LOW
FUEL PUMP PRESSURE OR INCOR.
RECT IGNITION
TIMING.
REPLACE
THE PLUG.
FIG. 19
-Spark Plug Inspection
IDENTIFIED BY DEPOSIT
BUILD-UP
CLOSING GAP
BETWEEN
ELECTRODES
.
CAUSED BY OIL OR
CARBON FOULING.
IF
DEPOSITS
ARE
NOT EXCESSIVE,
THE PLUG
CAN
BE
CLEANED.
IDENTIFIED BY SEVERELY
ERODED OR WORN ELECTRODES.
CAUSED BY
NORMAL WEAR
.
SHOULD
BE
REPLACED.
PRE-IGNITION
IDENliFIED BY MEL TED
ELECTRODES AND PDSSIBL Y
BL~TEREDIN
SULATOR.
METALLIC DEPOSITS ON
INSULA
TOR INDICATE ENGINE
DAMAGE.
CAUSED BY WRONG TYPE
OF FUEL
.
INCORRECT
IGNITION
TIMING
OR ADVANCE, TOO
HOT
A
PLUG. BURNT VALVES OR
ENGINE
OVERHEATING.
REPLACE
THE PLUG.
9-11
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