Content .. 1221 1222 1223 1224 ..
Chevrolet Silverado / GMC Sierra. Manual - part 1223
Cylinder Knocking Noise
Injector nozzles sticking open
Test injectors, see FUEL
SYSTEMS
Very low nozzle opening pressure
Test injectors and/or
replace
Loss of Engine Power
Restricted air intake
Remove restriction
EGR valve malfunction
Replace EGR valve
Blocked or damaged exhaust system
Remove restriction and/or
replace components
Blocked fuel tank filter
Replace filter
Restricted fuel filter
Remove restriction and/or
replace filter
Block vent in gas cap
Remove restriction and/or
replace cap
Tank-to-injection pump fuel supply blocked
Check fuel lines and
connections
Blocked fuel return system
Remove restriction
Incorrect or contaminated fuel
Replace fuel
Blocked injector nozzles
Check nozzle for
blockage, see FUEL
SYSTEMS
Low compression
Check valves, rings,
pistons, see ENGINES
Loud Engine Noise With Black Smoke
Basic timing incorrect
Reset timing, see FUEL
SYSTEMS
EGR valve malfunction
Replace EGR valve
Internal injection pump malfunction
Replace injection pump,
see FUEL SYSTEMS
Incorrect injector pump housing pressure
Check pressure, see FUEL
SYSTEMS
Engine Overheating
Cooling system leaks
Check cooling system and
repair leaks
Belt slipping or damaged
Check tension and/or
replace belt
2008 Chevrolet Silverado 1500
GENERAL INFORMATION Trouble Shooting - Basic Procedures
VACUUM PUMP DIAGNOSIS
FUEL INJECTION TROUBLE SHOOTING
BASIC FUEL INJECTION TROUBLE SHOOTING CHART
Thermostat stuck closed
Remove and replace
thermostat, see ENGINE
COOLING
Head gasket leaking
Replace head gasket
Oil Light on at Idle
Low oil pump pressure
Check oil pump operation,
see ENGINES
Oil cooler or line restricted
Remove restriction and/or
replace cooler
Engine Won't Shut Off
Injector pump fuel solenoid does not return fuel valve to
OFF position
Remove and check
solenoid and replace if
needed
CONDITION & POSSIBLE CAUSE
CORRECTION
Excessive Noise
Loose pump-to-drive assembly screws
Tighten screws
Loose tube on pump assembly
Tighten tube
Valves not functioning properly
Replace valves
Oil Leakage
Loose end plug
Tighten end plug
Bad seal crimp
Remove and re-crimp seal
NOTE:
This is GENERAL information. This article is not intended to be
specific to any unique situation or individual vehicle configuration.
The purpose of this Trouble Shooting information is to provide a list
of common causes to problem symptoms. For model-specific
Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING
articles available in the section(s) you are accessing.
CONDITION & POSSIBLE CAUSE
CORRECTION
Engine Won't Start (Cranks Normally)
Cold start valve inoperative
Test valve and circuit
2008 Chevrolet Silverado 1500
GENERAL INFORMATION Trouble Shooting - Basic Procedures
Poor connection;vacuum or wiring
Check vacuum and
electrical connections
Contaminated fuel
Test fuel for water or
alcohol
Defective fuel pump relay or circuit
Test relay and wiring
Battery too low
Charge and test battery
Low fuel pressure
Test pressure regulator
and fuel pump, check for
restricted lines and filters
No distributor reference pulses
Repair ignition system as
necessary
Open coolant temperature sensor circuit
Test sensor and wiring
Shorted W.O.T. switch in T.P.S.
Disconnect W.O.T.
switch, engine should start
Defective ECM
Replace ECM
Fuel tank residual pressure valve leaks
Test for fuel pressure drop
after shut down
Hard Starting
Disconnected hot air tube to air cleaner
Reconnect tube and test
control valve
Defective Idle Air Control (IAC) valve
Test valve operation and
circuit
Shorted, open or misadjusted T.P.S.
Test and adjust or replace
T.P.S.
EGR valve open
Test EGR valve and
control circuit
Poor Oxygen sensor signal
Test for shorted or circuit
Incorrect mixture from PCV system
Test PCV for flow, check
sealing of oil filter cap
Poor High Speed Operation
Low fuel pump volume
Faulty pump or restricted
fuel lines or filters
Poor MAP sensor signal
Test MAP sensor, vacuum
hose and wiring
Poor Oxygen sensor signal
Test for shorted or open
sensor or circuit
Open coolant temperature sensor circuit
Test sensor and wiring
2008 Chevrolet Silverado 1500
GENERAL INFORMATION Trouble Shooting - Basic Procedures
IGNITION SYSTEM TROUBLE SHOOTING
Faulty ignition operation
Check wires for cracks or
poor con- nections, test
secondary voltage with
oscilloscope
Contaminated fuel
Test fuel for water or
alcohol
Intermittent ECM ground
Test ECM ground
connection for resistance
Restricted air cleaner
Replace air cleaner
Restricted exhaust system
Test for exhaust manifold
back pressure
Poor MAF sensor signal
Check leakage between
sensor and manifold
Poor VSS signal
If tester for ALCL hook-
up is available check that
VSS reading matches
speedometer
Ping or Knock on Acceleration
Poor Knock sensor signal
Test for shorted or open
sensor or circuit
Poor Baro sensor signal
Test for shorted or open
sensor or circuit
Improper ignition timing
See VEHICLE
EMISSION CONTROL
LABEL (where
applicable)
Check for engine overheating problems
Low coolant, loose belts
or electric cooling fan
inoperative
NOTE:
For additional electronic fuel injection trouble shooting
information, see the appropriate article in the ENGINE
PERFORMANCE section (not all vehicles have Computer Engine
Control articles). Information is provided there for diagnosing fuel
system problems on vehicles with electronic fuel injection.
2008 Chevrolet Silverado 1500
GENERAL INFORMATION Trouble Shooting - Basic Procedures
Content .. 1221 1222 1223 1224 ..