Carburetor Replacement; Carburetor Overhaul - Jeep 1979 CJ-5 Technical & Service Manual

1 J - 1 2 FUEL SYSTEMS
PUMP " S " LINK
A R M
A C C E L E R A T O R
PUMP S H A F T
PUMP
D R I V E
SPRING
DISCHARGE
JET
I N T A K E
CHECK BALL
CHOKE
V A C U U M
D I A P H R A G M
DISCHARGE
CHECK B A L L
Fig. 1 J - 2 0 Pump Circuit
CHOKE V A L V E
CHOKE
C O N T R O L ,
ROD
• C H O K E COVER
80444
Fig. 1 J - 2 1 Choke Components
As the thermostatic coil is warmed by air rising
through the heat tube from the exhaust manifold, the
coil expands and exerts pressure to further open the
choke valve, keeping it fully open at operating
temperature.
If the engine is accelerated during the warm-up pe-
riod, the corresponding drop in the manifold vacuum
allows the thermostatic coil to momentarily close the
choke valve to provide a richer mixture.
A faster idle speed is provided to prevent stalling
during warm-up. The fast idle cam, actuated by the
choke shaft through connecting linkage, rotates into po-
sition against the fast idle screw. The cam is progres-
sively stepped to provide correct idle setting in
proportion to the choke valve opening. When the choke
valve reaches its fully open position, the cam rotates
free of the fast idle screw, allowing the throttle lever to
return to curb idle position when released.
If the engine floods during starting, the choke valve
may be opened to vent excess fuel by depressing the
accelerator pedal to the floor and cranking the engine.
With the accelerator linkage in this position, a tang on
the throttle lever contacts the fast idle cam, causing the
choke rod to move upward to open the choke valve a
predetermined distance.
CARBURETOR REPLACEMENT
Renewal
(1) Remove air cleaner.
(2) Code all lines attached to carburetor for aid dur-
ing installation.
(3) Remove accelerator cable from accelerator lever
and disconnect vacuum hoses, return spring, choke clean
air tube, PCV hose, fuel line, choke heat tube and sole-
noid wire, if equipped.
(4) Remove carburetor retaining nuts. Remove car-
buretor. Remove carburetor gasket from spacer.
Installation
(1) Clean gasket mounting surface of spacer. Install
replacement gasket on spacer. Position carburetor on
spacer and gasket and install nuts. To prevent leakage,
distortion or damage to carburetor body flange, alter-
nately tighten nuts in crisscross pattern.
(2) Connect fuel line, throttle cable, choke heat
tube, PCV hose, return spring, choke clean air tube, all
vacuum hoses and solenoid wire, if equipped.
(3) Adjust engine idle speed, idle fuel mixture and
solenoid. Refer to Chapter 1A—General Service and
Diagnosis.
(4) Install air cleaner.
CARBURETOR OVERHAUL
The following procedures apply to complete overhaul
with the carburetor removed from the engine.
A complete disassembly is not necessary when per-
forming adjustments. In most cases, service adjust-
ments of individual systems may be completed without
removing the carburetor from the engine. Refer to Serv-
ice Adjustment Procedures.
A complete carburetor overhaul includes disassembly,
thorough cleaning, inspection and replacement of all
gaskets and worn or damaged parts. It also includes idle
adjustment, mixture adjustment and fast idle adjust-
ment after the carburetor is installed. Refer to figure 1J-
22 for parts identification.
N O T E : When using an overhaul kit, use all parts in-
eluded in the kit.
N O T E : Flooding, stumble on acceleration, and other
performance problems are in many instances caused by
the presence of dirt, water, or other foreign matter in
the carburetor. To aid in diagnosing the problem, care-
fully remove the carburetor from the engine without
removing the fuel from the bowl. Examine the bowl
contents for contamination as the carburetor is
disassembled.