Chevrolet 1977 light duty truck, Руководство по обслуживанию

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INLET
CHECK BALL
Fig. 6C-22--Pump System
Fig. 6C-23--Choke System-2GC
ON-VEHICLE SERVICE
C A R B U R E T O R A D J U S T M E N T S
R efer to figure 6C-24 for the following adjustments:
• Float Level
• Float D ro p
• Pu m p Rod
R efer to figure 6C-25 for the following adjustments:
• Choke Coil Lever
• A utom atic Choke Coil-2GC
• Choke Coil Rod-2GV
Checking Carburetor Choke
1. Remove air cleaner. W ith engine off, hold
throttle h a lf open. O pen and close choke several times.
W atch linkage to be certain all links are connected and
there are no signs o f dam age.
2. If choke or linkage binds, sticks, or works
sluggishly, clean with C hoke C le a n e r X-20-A or
equivalent. Use cleaner as directed on can. R efer to
disassembly instructions for additional direction if
cleaning does not correct.
3. Visually inspect c a rb u re to r to be certain all
vacuum hoses are connected. Inspect hoses for cracks,
abrasions, hardness or other signs o f deterioration.
Replace or correct as necessary.
4. M ak e sure vacuum break d i a p h r a g m shaft is
fully extended w hen engine is off. If shaft is not fully
extended, replace vacuum break assembly. Start engine -
Vacuum break d ia p h ra g m sh aft should fully retract
within 10 seconds. If unit fails to retract, replace vacuum
break assembly.
R efer to figure 6C-26 for the following adjustments:
• Choke Rod (Fast Idle C am )
• Vacuum Break
•
U nloader
R efer to figure 6C-27 for the following adjustm ents:
• Idle Speed Adjustment-without solenoid.
• Idle Speed A djustm ent-with solenoid.
Checking Solenoid
1. T urn on ignition, but do not start engine. Turn
A / C to " o n " position.
2. O pen throttle to allow solenoid to extend, close
throttle
3. Disconnect lead at solenoid. Solenoid plunger
should drop away fro m throttle lever.
4. Connect solenoid lead. Plunger should move out
and contact the throttle lever. Solenoid m a y not be
strong enough to open the throttle, but the plunger
should move.
5. If plu n g er does not move in and out as lead is
disconnected and connected, insert test light (1893 bulb
or smaller) between the solenoid feed wire and ground.
6. If light lights, replace solenoid.
7. If light does not light, locate cause o f open
circuit in solenoid feed wire.
Idle Mixture
Idle mixture screws have been preset at the factory
and capped. Do not remove the caps du rin g norm al
engine maintenance.
Before suspecting the c arburetor as the cause o f
poor engine p erfo rm an ce or rough idle, check ignition
system including distributor, timing, spark plugs and