Hummer H1 (1992-1998). Manual - part 36

2-34. 1990 (6.2L) FUEL INJECTION PUMP (DB2829-4879) CALIBRATION

(Cont’d)

(e) Calibrating nozzles and injection lines:

(1) Eight 0.020-in. (0.5 mm) orifice plate nozzles set at 1700 ± 25 psi (11,721 ± 172 kPa).
(2) Eight 0.093-in. (2.36 mm) inside diameter by 25 in. (63.5 cm) long injection lines.

(f) Calibrating fluid conforming to SAE J967, maintaining a temperature of 110°-115°F (43°-46°C)

at the pump inlet over all speed and load ranges.

(g) Orifice fitting in the inlet line between the supply pump and shutoff valve, to maintain

constant fluid circulation and temperature.

b. Injection Pump Information

NOTE

All speeds are in engine rpm unless otherwise noted.

1. Injection pump operating speed is half of engine speed.
2. Injection pump rotation is counterclockwise.

3. Injection pump is timed to the outlet port in the 10 o’clock position, when viewed from the transfer

pump end.

c. Injection Pump Check (Prior to Service)

2.
3.

5.
6.

2-132

Before mounting the pump on the test stand, check the drive shaft for freedom of rotation in the
housing. Pump should be mounted securely in the appropriate adapter, and the intermediate
coupling checked for freedom of movement.
Connect supply and return lines securely.
Install high pressure injection lines. Use copper gaskets or steel washers where required. Leave fuel
line connections at the pump and nozzles loose.

Apply 17.6 V to electric shutoff solenoid and operate pump at 2000 rpm wide-open throttle (WOT)

for 10 minutes to bring to operating temperature and clear air from system.
Tighten all connections securely. Check connections for leaks while operating.
Check fuel delivery at 650 rpm (low idle). Fuel delivery should be 10-18 mm

/stroke. If fuel delivery

is not within the range specified, adjust low idle screw. Turn screw clockwise to decrease or counter-
clockwise to increase fuel delivery.

Check housing pressure at 650 rpm, while applying 17.6 V to housing pressure cold advance
solenoid. Housing pressure should be 0-1 psi (0-7 kPa) and 8-12 psi (55-83 kPa) when de-energized.
Check electric shutoff solenoid for pull-in with 17.6 V maximum with throttle lever in low idle

position at 400 rpm.
Fuel delivery measurement

(a) In order to minimize variations between readings due to residual oil in the graduates, the

following timed cycle should be used:
(1) Draw

(2) Settle 30 seconds
(3) Drain 30 seconds
(4) Draw

(5) Settle 30 seconds

(6) Read graduates
(7) Repeat cycle and average readings

2-34. 1990 (6.2L) FUEL INJECTION PUMP (DB2829-4879) CALIBRATION (Cont’d)

(b) Energize electric shutoff solenoid and check delivery against the chart below.

THROTTLE

CAM MOVEMENT

PRESSURE

RPM

POSTION

STROKE”

(DEGREES)

TRANSFER PUMP

HOUSING

150

WOT

28 min.

12 psi (83 kPa) min.

0-12 psi (0-83 kPa)

400

WOT

45 min.

400

WOT**

4 max.

650

Low idle

10-18

8-12 psi (55-83 kPa)

650

Low idle

1.25 min.

0-1 psi (0-7 kPa)

1500

21.5-23.5

1.0-3.5

2000

WOT

56 max.

60-62 psi (414-427 kPa)

2400

WOT

0.5-3.0

3200

Low idle

9.0-10.0

3500

WOT

48-53

4.5-6.5

3600

WOT

47 min.

3800

WOT

33 min.

4050

WOT

15 max.

125 psi (862 kPa) max.

* Maximum cylinder variation should be ± 6 mm

from the average flow of all cylinders.

** With housing pressure cold advance solenoid energized.

10. Disconnect pump and mount in holding fixture.
11. Using air timing gauge, check pump timing. Set to -0.5 to +1.5 degrees.
12. Total throttle travel from low idle to wide-open throttle should be 80-84 degrees.
13. Refer to para. 2-7, Engine Troubleshooting, to diagnose any malfunctions encountered during

checkout.

d. Injection Pump Settings (Following Pump Repair)

1. Roller-to-roller dimension must be 1.975 ± 0.0005 in. (50.17 ± 0.013 mm). With oversize cam ring

installed, roller-to-roller dimension will be 1.981 ± 0.0005 in. (50.32 ± 0.013 mm). Maximum
eccentricity allowed is 0.008 in. (0.20 mm) TIR.

2. Linkage gap must be 0.130-0.175 in. (3.30-4.45 mm).

(a)
(b)

(c)

(d)

(e)

(f)

(g)

Mount the pump horizontally in holding fixture and remove governor cover.
Hold the throttle lever in the wide-open throttle (WOT) position. Rotate pump drive shaft
counterclockwise until a click is heard as the rounded contact points on the governor arm
engauge the slots in the thrust sleeve. Continue to rotate the drive shaft until the gap between
the governor arm and pump housing is minimal.
Using linkage gap tool, check the clearance limits between the rear of the shutoff shaft and
the vertical tab on the linkage hook.
If adjustment is required, loosen governor linkage hook adjustment screw and extend the
linkage hook to its maximum open length (throttle lever must be in WOT).
Insert the appropriate step of the linkage gap tool between the vertical hook tab and the

throttle shaft, with the step facing the shaft. The tool must be held vertically and parallel
to the linkage hook tab.
With the linkage hook pin seated firmly in the governor arm slot and the governor arm in

the minima] gap position (step 2.(b)), shorten the linkage hook assembly until the face of the
vertical tab is flush against the tool. Tighten adjusting screw to 12-15 lb-in. (1 N•m).
Recheck linkage gap and adjust if necessary.

2-133

2-34. 1990 (6.2L) FUEL INJECTION PUMP (DB2829-4879) CALIBRATION (Cont’d)

4.
5.

6.
‘i’.

10.

11.
12.

13.

14.

15.

16.
17.

18.

19.

20.

21.

Set the throttle lever in correct low idle position prior to calibration using throttle lever gauge. The
low idle screw must beat 34± 2 degrees as measured between vertical centerline of throttle shaft
bushing bore and throttle connection stud.
Flush the pump with calibrating oil to remove metal chips and possible contamination.
Before mounting the pump on the test stand, check the drive shaft for freedom of rotation in the
housing. Pump should be mounted securely in the appropriate adapter, and the intermediate
coupling checked for freedom of movement.
Connect supply and return lines securely.
Install high pressure injection lines. Use copper gaskets or steel washers where required. Leave fuel
line connections at the pump and nozzles loose.

Apply 17.6 V to electric shutoff solenoid and operate pump at 2000 rpm (WOT) for 10 minutes to
bring to operating temperature and clear air from system.
Tighten all connections securely. Check connections for leaks while operating.

Set transfer pump pressure at 2000 rpm (WOT) for 60-62 psi (414-428 kPa); test stand boost should

be set at 5 ± 0.5 psi (34.5 ± 3.4 kPa).

Set return oil flow to 225-375 cc/minute at 2000 rpm (WOT).
Measure housing pressure:
(a) Check housing pressure at 650 rpm, with throttle shaft in low idle position, pressure should

be 8-12 psi (55-83 kPa).

(b) Energize housing pressure cold advance solenoid with 17.6 V. Housing pressure should be

0-1 psi (0-7 kPa).

With governor cover removed and throttle shaft in low idle position, set min-max governor assembly
for 7-9 mm

/stroke at 650 rpm (fuel reading with cover installed).

NOTE

If low idle screw adjustment is required, refer to step 3. Adjust-
ment is ± 1 turn from the point in step 3.

At 650 rpm, adjust low idle screw for 13-15 mm

/stroke for the remainder of the setting and checking

procedures.
During and at the completion of all settings, ensure face cam to throttle shaft end play measures
0.004-0.006-in. (0.10-0.15 mm) between throttle shaft spacer and housing.
At 3500 rpm (WOT), rotate face cam to its maximum lift position in contact with the cam roller.
At 3500 rpm (WOT), adjust trimmer screw for 5.5 degrees cam advance and set fuel delivery to
50-51 mm

/stroke.

Set guide stud for 35-37 mm

/stroke at 3800 rpm (WOT). Tighten guide stud nut to 80-90 lb-in.

(9-10 N•m) and check dimension from top of nut to top of guide stud for 0.400-in. (10.2 mm)

maximum.
Set throttle for 21.5-23.5 mm

/troke at 1500 rpm and rotate face cam to obtain 2.25 degrees cam

advance.
Tighten face cam screw to 28-30 lb-in. (3 N•m) and check face cam retention.
(a) Put 0.005-in. (0.127 mm) feeler gauge between throttle shaft mylar washer and housing boss.
(b) Put throttle shaft in idle position. Squeeze throttle shaft and face cam tightly toward each

other and rotate face cam as lower roller rests approximately in middle at low idle step.
Tighten screw to 30 lb-in. (3 N•m) with torx drive and remove feeler gauge.

Set total throttle travel. With throttle in low idle position, align zero degree mark on protractor

with center of rib on rocker lever. Move throttle to WOT and adjust maximum travel screw to
80-84 degrees.

NOTE

Any changes to pump or settings after this point will require
retesting of pump, starting with step 12.

2-134

2-34. 1990 (6.2L) FUEL INJECTION PUMP (DB2829-4879) CALIBRATION (Cont’d)

22. Fuel delivery measurement:

(a) In order to minimize variations between readings due to residual oil in the graduates, the

following timed cycle should be used:
(1) Draw
(2) Settle 30 seconds
(3) Drain 30 seconds
(4) Draw
(5) Settle 30 seconds
(6) Read graduates
(7) Repeat cycle and average readings

(b) Check points:

(1) At 1500 rpm (WOT) de-energize electric shutoff solenoid. Delivery should be 4 mm

/stroke

maximum.

(2) Re-energize electric shutoff solenoid and check delivery against the chart below.

THROTTLE

MM’/

CAM MOVEMENT

PRESSURE

RPM

POSITION

STROKE*

(DEGREES)

TRANSFER PUMP

HOUSING

150

WOT

28 min.

12 psi (83 kPa) min.

0-12 psi (0-83 kPa)

400

WOT

45 min.

400

WOT**

4 max.

400

Low idle***

650

Low idle

12-16

8-12 psi (55-83 kPa)

650

Low idle

1.25 min.

0-1 psi (0-7 kPa)

1500

21.5-23.5

1.0-3.5

2000

WOT

56 max.

60-62 psi (414-427 kPa)

2400

WOT

0.5-3.0

3200

Low idle

9.0-10.0

3500

WOT

48-53

4.5-6.5

3600

WOT

47 min.

3800

WOT

33 min.

4050

WOT

15 max.

125 psi (862 kPa) max.

* Maximum cylinder variation should be ± 6 mm

from the average flow of all cylinders.

** With housing pressure cold advance solenoid energized.

*** Check electric shutoff solenoid for pull-in with 17.6 volts maximum.

23. Disconnect pump and mount in holding fixture.
24. Using air timing gauge, check pump timing. Set to +0.25 degree ± 0.50 degree.
25. Tighten all fasteners to specifications, refer to para. 2-32d.
26. Apply sealing compound as follows:

(a) Apply one drop at interface of maximum travel screw and locknut.

CAUTION

Do not allow sealing compound to enter gap between face cam and
housing. Binding of the throttle shaft may result.

(b) Apply one drop to threaded end of face cam screw where it protrudes from face cam.

sealing compound does not enter hex recess of screw.

27. Install tamper-proofing cap on guide stud.

2-135

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