Hummer H1 Service Manual page 146

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PROBLEM
Low Power, 1. Contaminated or low-quality fuel.
Sluggish Accel-
2. High fuel temperature.
eration
3. Restriction in air intake system.
4. Fuel tank vent or return line restriction.
5. Exhaust system restriction.
6. Air leak at injector or line.
7. Brake drag.
8. Torque converter problem. Overrunning
clutch failure, or converter clutch binding, or
slipping. Either fault will cause high fuel
consumption and require more than normal
throttle opening for acceleration.
9. Engine compression low.
10. Injection pump mistimed.
11. Turbo diesel electronic accelerator fault such
as short, ground, loose connection indicate
potentiometer failure.
12. One or more injectors failing.
13. Air leak at intake manifold.
14. Turbocharger inoperative or no boost.
15. Sensor failure (coolant or air temp, baro or
boost sensors, etc.).
16. PCM signal voltage too low.
17. Injection pump fault.
5745159
Fuel System Diagnosis—Diesel Engine
POTENTIAL CAUSE
Fuel, Emissions, and Exhaust
CORRECTION
1. Drain, flush, and refill fuel system.
2. Normal condition in high ambient.
3. Remove and clean filter, housing, weathercap,
hose, air horn.
4. Clear restrictions, replace lines.
5. Inspect entire system for damage and repair as
needed. If vehicle is used for off-road operation,
look for kinking, bent, or flattened pipes or
muffler.
6. Tighten loose fittings or replace lines if necessary.
7. Inspect brake components. Look for seized or
binding caliper piston, master cylinder problem, or
failed hydro-boost.
8. Test operation with scan tool. Use snapshot mode
to record maximum data. Replace converter if
either clutch is damaged.
9. Run compression test. Repair valves, cam, chain,
rings as needed.
10. Check and correct pump timing. Replace either
pump gear if damaged.
11. Check pedal potentiometer wires and connections.
Test with scan tool if check throttle light is on.
Repair wiring, or replace pedal assembly.
12. Remove and test injectors. Replace faulty injectors
as needed.
13. Locate with soap and water solution (or oil).
Tighten bolts, replace gaskets, or replace manifold
if required.
14. Check boost output. Replace wastegate actuator if
leaking. Repair vacuum line if damaged. Replace
turbocharger if compressor or turbine wheel vanes
are broken, chipped, or if compressor shaft is
seized/broken.
15. Locate with scan tool. Test with multimeter and
replace as needed.
16. Check battery voltage and generator output. Repair
or replace parts as needed if voltage is below 10, or
above 16.
17. Replace pump.
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