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6C-6
1977 PONTIAC SERVICE M A N U A L
ENGINE STARTS AND RUNS BUT SOMETIMES
OIL PRESSURE SWITCH. SCRAPE WITH
ELECTRIC FUEL PUMP, TEMPERATURE PRESSURE
AND KEY BUZZER OPERATION
THE ELECTRIC FUEL PUMP IS LOCATED I N THE FUEL
TANK INTEGRAL WlTH THE GAUGE UNIT. BUT IS SEPARATELY
SERVICEABLE. THE PUMP OPERATES UNDER THE FOLLOWING
TWO CONDITIONS:
1. IGNITION I N START POSITION, NO OIL PRESSURE
2. IGNITION I N RUN POSITION, O I L PRESSURE (ENGINE
RUNNING).
THE TWO-POSITION OIL PRESSURE SWITCH CONTROLS PUMP
OPERATION. WlTH NO O I L PRESSURE, DURING CRANKING,
CURRENT FROM THE STARTER SOLENOID PURPLE WlRE
FEED. GOESTHROUGH THE OIL PRESSURE SWITCH, TO THE
OARK BLUE WlRE TO THE COWL CONNECTOR. THEN THROUGI
THE PlNK WlRE TO THE ELECTRIC FUEL FUSE I N THE
FUSE PANEL TO THE DARK BLUE WlRE TO THE FUEL PUMP.
ONCE THE ENGINE STARTS, AND THERE IS O I L PRESSURE,
THE O I L PRESSURE SWITCH DIRECTS CURRENT FROM THE
PlNK WlRE (FROM THE IGNITION SWITCH) TO THE DARK
BLUE WIRE. THROUGH THE FUSE. AND TO THE PUMP.
THE TEMPERATURE PRESSURE LAMP LIGHTS UNDER THE
FOLLOWING CONDITIONS:
1.
NO O I L PRESSURE. IGNITIQN IN RUN
2. ENGINE OVERHEATED, IGNITION IN RUN
THE TEMPERATURE PRESSURE LAMP RECEIVES ITS FEED
THROUGH THE PlNK WlRE FROM THE GAUGES FUSE AT
THE FUSE PANEL.
ENGINE STARTS HARD SOMETIMES, FUEL ADDED
TO CARBURETOR TO START ENGINE
AN ENGINE PROBLEM WHICH CAUSES
HARD
STARTING COUPLED WlTH AN INOPERATIVE
FUEL PUMP START FEED MAY CAUSE THE
ENGINE NOT TO START AT A L L UNLESS FUEL
IS ADDED TO THE CARBURETOR. THE
PROCEDURE BELOW CHECKS THE PUMP
START FEED CIRCUIT. WHEN I T HAS BEEN
DETERMINED THAT THE PUMP START FEED
ISOK, THEN REFER TO THE CARBURETOR
SECTION FOR DlAGNOlS OF THE HARD
STARTING CONDITION.
CHECK TEMPERATURE PRESSURE LAMP
OPERATION, IGNITION IN RUN POSITION.
ENGINE STOPPED. TEMPERATURE
PRESSURE LAMP SHOULD BE ON.
TEMPERATURE PRESSURE
TEMPERATURE PRESSURE
LAMP OFF
.
LAMP ON
TO 12 VOLTS AND PROBE PURPLE
SECTION FOR DlAGNOlS OF
REPLACE O I L PRESSURE
REPAIR OPEN IN PURPLE WIRE
FROM O I L PRESSURE SWITCH
CONNECTOR TO STARTER SOLENOID.
1
ELECTRIC FUEL PUMP, TEMPERATURE PRESSURE INDICATOR.
I
THE GROUND SIDE IS COMPLETED THROUGH THE FOLLOWING
INDICATOR, AND KEY BUZZER SCHEMATIC
TWO POSSIBLE PATHS:
I
CLOCK
ELECTRIC
1.
THROUGH THE DARK BLUE WIRE TO THE KEY BUZZER,
LIGHTER
F U E L
STARTER
THROUGH THE DIODE I N THE KEY BUZZER, THROUGH
CO
SOLENOID
PURPLE
THE DARK BLUE WHITE STRIPE WIRE TO THE COWL
Fq
0 1 L
PRESSURE
SWITCH
CONNECTOR (WHERE I T JUNCTIONS WlTH THE DARK BLUE
.t-
WlRE TO THE OIL PRESSURE SWITCH, AND THE PlNK
WlRE TO THE ELECTRIC FUEL FUSE), THROUGH THE
DARK BLUE WlRE T O T H E O I L PRESSURE SWITCH,
THROUGH THE OIL PRESSURE SWITCH TO THE
PURPLE WIRE (NO OIL PRESSURE) TO THE STARTER
C
SOLENOID. TO GROUND THROUGH THE STARTER SOLENOID
2 OR THROUGH THE DARK BLUE WlRE TO THE HARNESS
JUNCTION, THROUGH THE DARK GREEN WIRE, TO THE
TEMPERATURE SWITCH TO GROUND (SWITCH CLOSED,
ENGINE OVERHEATED).
THE KEY BUZZER IS FED BY THE ORANGE WlRE
FROM THE CLOCK LIGHTER COURTESY FUSE A T
THE FUSE PANEL I T BUZZES WHEN THE PlNK BLACK
STRIPE WlRE IS GROUNDED THROUGH THE KEY SWITCH
IN THE STEERING COLUMN (KEY IN IGNITION) AND
DRIVER'S DOOR JUMP SWITCH (DOOR OPEN)
THE FUEL GAUGE OPERATES IDENTICALLY TO THAT
IN OTHER BUICKS. THE INSTRUMENT PANEL
GAUGE UNlT GETS FEED THROUGH THE PlNK WlRE
FROM THE GAUGES FUSE. THE TAN WlRE CONNECTS
THE GAUGE TO A VARIABLE RESISTANCE GROUND
THROUGH THE SENDING UNlT I N THE FUEL TANK.
GAUGES
F L
I
INT BODY
NECTOR
ORANGE
DARl
-. .". .
~ G N ~ ? ~ O N CONNECTOR
TEMPERATURE
SWTICH
PRESSURE
?
-
KEY BUZZER
-
BLACK
STRIPE
KEY
y
.
C
u
FUEL GAUGE
FUEL GAUGE
-
SENDING UNIT
I
K BLUE WHITE STRIPE
DARK BLUE
TRUNK CONNECTOR
Fig. 6C-5 Electric Fuel Pump, Temperature-Pressure Indicator Lamp, And Key Buzzer Diagnosis
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