Hummer H1 (2002+). Manual - part 37

 

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 Fuel, Emissions, and Exhaust  3-9

  

®

 

5745159

Low Power, 
Sluggish Accel-
eration

1.

Contaminated or low-quality fuel.

1.

Drain, flush, and refill fuel system.

2.

High fuel temperature.

2.

Normal condition in high ambient.

3.

Restriction in air intake system.

3.

Remove and clean filter, housing, weathercap,
hose, air horn.

4.

Fuel tank vent or return line restriction.

4.

Clear restrictions, replace lines.

5.

Exhaust system restriction.

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.

Air leak at injector or line.

6.

Tighten loose fittings or replace lines if necessary.

7.

Brake drag.

7.

Inspect brake components. Look for seized or
binding caliper piston, master cylinder problem, or
failed hydro-boost.

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.

8.

Test operation with scan tool. Use snapshot mode
to record maximum data. Replace converter if
either clutch is damaged.

9.

Engine compression low.

9.

Run compression test. Repair valves, cam, chain,
rings as needed.

10. Injection pump mistimed.

10. Check and correct pump timing. Replace either

pump gear if damaged.

11. Turbo diesel electronic accelerator fault such 

as short, ground, loose connection indicate 
potentiometer failure.

11. Check pedal potentiometer wires and connections.

Test with scan tool if check throttle light is on.
Repair wiring, or replace pedal assembly.

12. One or more injectors failing.

12. Remove and test injectors. Replace faulty injectors

as needed.

13. Air leak at intake manifold.

13. Locate with soap and water solution (or oil).

Tighten bolts, replace gaskets, or replace manifold
if required.

14. Turbocharger inoperative or no boost.

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. Sensor failure (coolant or air temp, baro or 

boost sensors, etc.).

15. Locate with scan tool. Test with multimeter and

replace as needed.

16. PCM signal voltage too low.

16. Check battery voltage and generator output. Repair

or replace parts as needed if voltage is below 10, or
above 16.

17. Injection pump fault.

17. Replace pump.

 

 Fuel System Diagnosis—Diesel Engine

 

PROBLEM

POTENTIAL CAUSE

CORRECTION

 

3-10

Fuel, Emissions, and Exhaust

 

___________________________________________

  

®

 

Knock-Ping 
Under Accelera-
tion.

1.

Contaminated, incorrect, or low quality fuel.

1.

Drain, flush, and refill fuel system.

2.

Air leak in fuel delivery system.

2.

Inspect injector line fittings. Bleed injectors and
tighten any loose fittings. Check all fuel supply
lines for leaks.

3.

Engine overheat caused by low coolant level.

3.

Add coolant. Repair leaks.

4.

Coolant and/or air temperature sensor fault.

4.

Check with scan tool and replace as needed.

5.

Injection pump timing off.

5.

Check and correct as needed.

6.

Worn valve seals or guides allowing oil into 
combustion chambers.

6.

Repair engine as required.

7.

Carbon buildup on pistons and in chambers 
as result of substandard fuel, additives, or oil 
entering chamber past worn rings or through 
valve guides.

7.

Use combustion chamber conditioner to break
down carbon. Engine disassembly will be
necessary if conditioner is not effective.

Black, White, or 
Blue Smoke at 
Idle and/or 
Under Load

1.

Incorrect or substandard fuel.

1.

Drain and refill tanks with correct fuel.

2.

Glow plug fault (white smoke at cold start-
up).

2.

Test and replace failed plugs, wires, or relay/
controller.

3.

Worn piston rings, valve guides or stem seals 
(blue smoke) allowing oil into combustion 
chamber. High oil consumption may also be 
noted by owner.

3.

Repair guides, replace seals, or replace rings as
needed.

4.

Overrich mixture (black smoke) caused by 
stuck injector.

4.

Test and replace any injectors that fail pressure
leak test.

5.

Low fuel pump pressure (at pump).

5.

Replace fuel-lift pump if pressure is below 5.8 psi
(40 kPa) at pump.

6.

Timing advanced (white smoke at cold idle, 
black smoke under load when hot).

6.

Check and adjust as necessary.

7.

Cold advance solenoid or switch fault (white 
smoke).

7.

Test and replace solenoid/switch as required.

Rough Idle and/
or Hesitation 
Under Accelera-
tion

1.

Substandard fuel.

1.

Drain and replace fuel.

2.

Air leak in fuel line or injector.

2.

Locate  and  correct  leak.  Bleed  all  injectors
afterward.

3.

Fuel filter cap or tank vent restriction.

3.

Replace cap or vent hose as required.

4.

Injector fault.

4.

Locate and replace faulty injector.

5.

Intake manifold leak.

5.

Replace manifold or gaskets as needed.

 

 Fuel System Diagnosis—Diesel Engine

 

PROBLEM

POTENTIAL CAUSE

CORRECTION

 

___________________________________________

 

 Fuel, Emissions, and Exhaust  3-11

  

®

 

5745159

 

SCAN TOOL DIAGNOSIS

 

The scan tool is needed for operational testing of electronic
components such as the PCM, electronic accelerator pedal po-
tentiometer, and engine sensors.

The scan tool is connected to the vehicle electrical system
through the diagnostic/data link connector. The connector is a
black 16-way connector. It is located under the instrument
panel near the steering column.

Refer to Section 2 for detailed information on scan tool use.

 

Fuel Pump Pressure Test

 

Fuel pump pressure should be 5.8-8.7 psi (40-60 kPa) at idle.

1.

Disconnect fuel line at fuel filter inlet port.

2.

Install a tee adapter in fuel line between pump and filter
inlet port.

3.

Connect test gauge to tee adapter. Gauge should have
pressure capacity up to 20 psi (138 kPa).

4.

Start and run engine and record fuel pump pressure.

5.

If pump pressure is less than 5.8 psi (40 kPa), replace
pump and retest pressure.

6.

Remove pressure gauge and tee adapter. Reconnect fuel
line to filter inlet.

 

Diesel Fuel Injector Test

 

WARNING:  Nozzle tester tool J–29075-AMG dupli-
cates normal injector operating pressures which can
exceed 1700 psi (117 bar). Never place hands or arms
near the injector nozzle during the test. The high pres-
sure, finely atomized spray from the nozzle can pene-
trate flesh, destroy tissue, and result in blood poisoning.
It is recommended that a clear protective receptacle be
positioned around the injector to contain the spray. A
receptacle can be fabricated from 3/16 to 1/4 in. clear
plastic for test purposes.

 

The test requires a nozzle tester tool J–29075-AMG, injector
adapter kit J–29079-125, a length of clear plastic 1/8 or 3/16
I.D. tubing, and a drip pan.

1.

Locate faulty injector by loosening fuel line fitting 
momentarily at each injector. Faulty injector will not have 
much affect on engine operation.

2.

Remove suspect injector(s) from engine.

3.

Install clear plastic tube on fuel drain/return ports on
injector.

4.

Attach injector to fitting and line on test tool (Figure 3-10).

5.

Close shutoff valve on tool (Figure 3-10).

 

Figure 3-10:   Pressure Testing Diesel Fuel Injector

 

6.

Position drip pan under injector.

7.

Place protective receptacle or box around injector.

8.

Pump test tool handle to fill line, fitting, and injector with
test fluid.

9.

Test injector nozzle opening pressure as follows:

a.

Open test tool shutoff valve 1/4 turn.

b.

Press tool pump handle slowly downward and note
pressure where test gauge needle stops.

c.

Maximum observed pressure represents injector
opening pressure. Compare values to Fuel Injection
Nozzle table on page 3–12.

d.

Replace injector if opening pressure is less than speci-
fied.

e.

Replace injector if it does not have a uniform conical
spray pattern.

10. Test injector nozzle leakage as follows:

a.

Open test tool shutoff valve an additional 1/2 to 1 1/2
turns.

b.

Press tool pump handle slowly downward until test
tool gauge is at 1400 psi (95 bar) and observe injector
nozzle tip.

NOZZLE TESTER

J–29075-AMG

PUMP

HANDLE

SHUTOFF

VALVE

KNOB

FITTING

AND LINE

INJECTOR

NOZZLE

PRESSURE

GAUGE

PART OF

J–29079-125

ADAPTER KIT

 

3-12

Fuel, Emissions, and Exhaust

 

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c.

A drop of fluid should form and remain on nozzle tip
for at least 10 seconds.

d.

Replace nozzle if fluid falls off tip in less than 10
seconds.

11. Test injector chatter as follows:

a.

Close test tool shutoff valve.

b.

Press tool pump handle slowly downward and listen
for a chatter like noise.

c.

If noise is not produced, pump handle faster and
check for chatter noise again.

d.

If injector produces a chatter, or hissing, squealing
sound, injector is OK. Noise indicates nozzle needle
valve is moving freely and that seat, guide, and pintle
are also OK.

e.

Replace nozzle if it does not produce noise. Lack of
noise indicates failure of valve, spring, or seat.

 

        

 

Engine Coolant Temperature 
Sensor Test

 

The coolant temperature sensor is a thermistor that provides a
temperature signal to the PCM (Figure 3-11). The signal is in
the form of a voltage that changes according to sensor resis-
tance. At low temperatures, resistance and voltage are both high.
As temperature increases, resistance and voltage both decrease.

A sensor fault will cause the check engine light to illuminate
and the torque converter clutch to apply early. If the sensor
fails in a cold mode, it can produce overrich operation and
rough idle.

 

High Temperature—Low Resistance Test

 

1.

Allow engine to cool down. Coolant should be at ambient 
temperature for test.

2.

Connect scan tool, start engine, and note sensor temperature.

• If indicated temperature is 266° F (130° C) or above, 

continue test.

• If indicated temperature agrees with ambient, sensor is 

OK.

3.

Disconnect sensor and note temperature indicated on scan tool:

• If indicated temperature drops to -22° F (-30° C), sensor 

has failed and should be replaced.

• If indicated temperature does not drop, problem is with 

sensor wiring or connections.

 

 Fuel Injection Nozzle

 

PART NO.

COLOR 

RING

APPLICATION

OPENING

PRESSURE

NEW

USED

 

(05743223)

Orange

6.5L TD 96-99

L65 (VIN Z)

2030-2204 psi

140-152 bar

1700-2204 psi

117-152 bar