Chevrolet LIGHT DUTY TRUCK (SERIES 10-35) Service Manual page 22

C-10 S park Plug W ire s
Clean wires. Remove corrosion on terminals. Check
the wires for checks, burns, cracks or other damage. Check
the boot fit at distributor cap and spark plugs. Replace wire
if damaged or if corrosion cannot be cleaned.
C -1 1 Spark Plugs
Replace as shown on Schedule. Use the type shown on
underhood label.
C -12 Tim ing and D istributor Cap
Adjust timing to underhood label specifications. Check
the inside and outside of the cap and rotor for cracks, carbon
tracking and corrosion. Clean or replace as needed.
C -13 C arburetor Vacuum Break
Check that linkage works properly correct any binding.
Check hoses for proper hookup and condition. Replace
parts as needed. If necessary, reset vacuum break as shown
in Section 6C.
C -14 A ir C leaner Elem ent
Replace at mileage shown on Schedule. Replace more
often under dusty conditions.
C -1 5 Evaporation Control System (ECS)
Check all fuel and vapor lines and hoses for proper
hookup routing and condition. Check that bowl vent and
purge valves work properly, if equipped. Remove canister,
check for cracks or damage. Replace as needed. Replace
canister filter.
M AINTENANCE AND LUBRICATION
C -16 Fuel Cap, Fuel Lines, and Fuel T an k
Check the fuel tank, cap and lines for damage or leaks.
Remove fuel cap, check gasket for an even filler neck
imprint, and any damage. Replace parts as needed.
C -17 Engine Idle M ix tu re (4.8L; L6 Only)
At designated intervals or in case of a major carburetor
overhaul, or when poor idle quality exists, adjust mixture
by a mechanical method (lean drop), following the
specifications shown on the label under the hood.
C -18 M an ifo ld H eat V alve
Some engines are equipped with a manifold heat valve
which should be inspected and repaired as necessary to
insure free operation.
C -19 T h ro ttle Return Control (TRC) System
Check hoses for proper connections,
abrasion, or deterioration and replace as necessary. Check
for proper operation of system.
Check for shorted or broken wires and ensure electrical
connectors are fully engaged at distributor, speed switch and
vacuum solenoid.
C -20 C rankcase V en tilatio n System
Clean oil fill tube breather cap and filter assemblies
(both valve covers) each 6,000 miles (9 600 km).
Replace oil fill tube breather cap and ventilation
regulator valve assembly each 30,000 miles (48 000 km).
Inspect rubber fittings and replace as required, and
clean tubes each 30,000 miles (48 000 km).
OB-15
cracking,
LIGHT DUTY T R U CK SER V IC E MANUAL