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PART 10-1- GENERAL FUEL SYSTEM
10-3
FUEL PUMP, TANK AND LINES DIAGNOSIS GUIDE (Continued}
FUEL PUMP NOISE
FUEL TANK AND/OR INLET
LINE HOSES COLLAPSED
AIR DUCT
1. Place the air duct assembly in
a container of cool water (below
75o
F.). Be sure that the thermostat
is covered by the water.
2. Place a thermometer in the water
and observe the temperature.
3. With the water temperature at
75o
F. or below, the valve should be
in the HEAT -ON position.
4. Using a hot plate or other suit-
able device, heat the water slowly.
5. When the water temperature
reaches
85°
F., the valve should
start to open. If the valve does not
start to open at this time, stabilize
the water temperature at 85° F.
for eight minutes before condemn-
ing the unit.
6. When the water temperature
reaches
100°
F. or higher, the valve
should be in the full HEAT-OFF
position.
7. If the operation of the valve
is unsatisfactory, remove the ther-
mostat and spring assembly and
check the valve plate shaft for bind-
ing.
CARBURETOR DIAGNOSIS GUIDE
FLOODING
HARD STARTING
STALLING (ENGINE HOT)
Rocker arm, eccentric or push rod
worn.
Mounting bolts loose.
Fuel tank vent in filler cap ob-
structed.
8. If the valve plate moves freely,
replace the thermostat and spring
assembly. Retest the HEAT-ON and
the REA T -OFF temperatures.
9. If the valve does not operate
correctly, adjust the thermostat rod.
By increasing the rod length, the
valve plate will be moved toward
the HEAT-OFF position. By de-
creasing the rod length, the valve
plate will be moved toward the
REA T-ON position.
CARBURETOR
Dirt accumulation in the fuel and
air passages, improper idle adjust-
ments, and improper fuel level are
the major sources of carburetor
troubles.
TESTS
Idle Speed-Up Control
1. Remove the air cleaner. Operate
the engine and the air conditioner.
2.
Place a finger on the air passage
inlet tube projecting through the air
horn. If the idle speed-up control
unit is operating correctly, the pull
of vacuum will be sufficient to be
High fuel level.
Loose fuel inlet needle valve seat
or seat gasket damaged or missing.
Excessive fuel pump pressure.
Sticking and/or restricted float op-
eration.
Incorrect starting procedure.
Automatic choke malfunction.
Incorrect choke linkage adjust-
ment.
Incorrect fast idle adjustment.
High carburetor fuel level.
Incorrect accelerator pump stroke
Improperly adjusted or defective
carburetor dashpot.
Engine idle speed too slow.
Incorrect idle fuel mixture.
Insufficient fuel supply to carbure-
tor.
Coolant control thermostat defec-
tive.
Rocker arm spring weak or
broken.
felt by finger application and the
engine rpm will decrease. If the
engine rpm does not decrease or no
suction is indicated at the inlet tube,
the fast idle solenoid
is
malfunction-
ing and further tests are required.
3. Check for current at the sole-
noid terminals with the appropriate
meter.
If
no current is present, check
the air conditioner electrical sys-
tem for the cause of the malfunc-
tion.
If
current is present, remove
the solenoid and check the solenoid
valve and seat for damage. If the
seat is damaged, replace the entire
assembly.
If
the valve is damaged,
replace the valve only. If both the
valve and seat are undamaged and
the unit is free of dirt, replace the
solenoid.
Accelerating Pump Discharge
1. Remove the air cleaner.
2.
Open the primary throttle plates
and observe the fuel flow from the
accelerating pump discharge nozzles.
If
the system is operating correctly,
a quick steady stream of fuel will
flow from the discharge nozzles.
Leaking carburetor float.
Float tab surface rough.
Dirt or foreign material in fuel
holds float needle valve open.
Worn needle valve and seat.
adjustment.
Fuel filter or supply lines restricted
with dirt, water, or ice.
Carburetor leaking and/ or flood-
ing.
Insufficient fuel supply to carbure-
tor.
Carburetor air, hot and cold valve
malfunctioning.
Dirt, water, or ice in fuel filter.
Fuel tank vented cap restricted.
Fuel lines restricted or leaking air.
Carburetor icing (cold, wet, or
humid weather).
CONTINUED ON NEXT PAGE
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Troubleshooting
