Chevrolet Light Duty Truck 1973 Service Manual page 404

6-68 ENGINE
a.
Corroded or loose battery terminal connections
and/or weak battery.
Broken or loose ignition wires and/or faulty
ignition switch.
c.
Excessive moisture
system.
d.
Damaged distributor rotor, cracked distributor cap
and/or corroded distributor contact points.
e.
Fouled spark plugs and/or improper spark plug
gaP-
a.
Air leaks between intake manifold and head.
b.
Blown head gasket.
c.
Worn timing chain or sprockets.
d. Worn camshaft lobes.
a. Spark plugs damp or gap incorrectly set.
b. Excessive moisture on ignition wires and caps.
c. Leaks in ignition wiring.
d. Ignition wires making poor contact.
e. Uneven compression.
f. Burned, pitted or incorrectly set contact points.
g. Faulty coil or condenser.
h. Worn distributor cam or cracked distributor cap.
i. Incorrect carburetor idle adjustment and/or dirty
jets or plugged passages in carburetor.
a. Dirt and water in gas line or carburetor.
b. Fouled carburetor jets.
c. Incorrect ignition timing.
d. Points dirty, pitted or incorrectly spaced.
e. Excessive play in distributor shaft.
f. Insufficient spring tension on points.
Distributor cam lobe worn.
g-
h. Weak coil or condenser.
i. Spark plugs dirty or damp and/or gaps set too wide.
DIAGNOSIS
ENGINE FAILS TO START
on plugs, caps or ignition
ENGINE LOPES WHILE IDLING
ENGINE MISSES WHILE IDLING
ENGINE MISSES AT VARIOUS SPEEDS
CAUSE
f.
Weak or faulty coil.
Carburetor flooded and/or fuel level in carburetor
bowl not correct.
h. Dirt and water in gas line or carburetor.
i. Sticking choke.
Faulty fuel pump.
j-
k. Faulty solenoid or starting motor.
Park or neutral switch inoperative.
CAUSE
e. Overheated engine.
f. Plugged crankcase vent valve.
g. Faulty fuel pump.
h. Leaky exhaust gas recirculation valve.
CAUSE
j. Foreign matter, such as dirt or water, in gas line or
carburetor.
k. Air leak at carburetor mounting gasket.
1. Choke inoperative.
m. Faulty spark advance mechanism.
Burned, warped, pitted, or sticking valves.
Incorrect valve lifter clearance.
Low compression.
Leak in exhaust gas recirculation valve.
CAUSE
Insufficient point dwell.
j-
k. Detonation or pre-ignition.
1. Excessively worn fuel pump diaphragm.
m. Weak valve spring.
n. Worn camshaft lobes.
o. Engine overheating.
P- Sub-standard fuel.
Leak in exhaust gas recirculation valve.
q-