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Hummer H1 (1992-1998). Manual - part 37

2-35. (6.5L) FUEL INJECTION PUMP (DB2831-5149) CALIBRATION

This task covers:

a. Test Bench Requirements

c. Injection Pump Check (Prior to Service)

b. Injection Pump Information

d. Injection Pump Settings (Following Pump Repair)

INITIAL SETUP:

Tools

Manual References

General mechanic’s tool kit:

automotive (Appendix E, Item 1)

Test Equipment

Special Tools

Digital tachometer

Roller-to-roller setting tool

(Appendix E, Item 45)

Voltage source (variable)

Pressure gauge (0-160 psi, 1 psi increments)

Linkage gap tool (Appendix E, Item 49)

Pressure gauge (0-30 psi)

Automatic advance indicator

(Appendix E, Item 50)

Vacuum gauge (0-30 in. Hg)
Flowmeter with three-way valve

Throttle lever gauge (Appendix E, Item 51)

Temperature gauge (0°-250°F)

Protractor (Appendix E, Item 52)

Zero-backlash coupling device

Air timing gauge (Appendix E, Item 53)

Calibrating nozzles and lines

Holding fixture (Appendix E, Item 46)

Orifice 13211

Torx drive (Appendix E, Item 42)

Calibration stand

Materials/Parts

Calibrating fluid (Appendix B, Item 4)
Sealing compound (Appendix B, Item 19)

NOTE

The following calibration procedure applies to 6.5L fuel injection
pumps. Refer to para. 2-34 for calibration on 1990 6.2L and above
pumps and para. 2-33 for pre-1990 6.2L pumps.

a. Test Bench Requirements

The fuel injection pump requires a test bench capable of at least 2,250 rpm shaft speed. The test bench

must be equipped with the following items:
(a) A zero-backlash coupling device.

(b) A digital tachometer.

(d) Test gauges:

(1) 0-160 psi (0-1103 kPa) pressure gauge calibration 1 psi increments to meaure transfer pump

pressure. This gauge should be located as close as possible to the pump, with an in-line shutoff

(2)
(3)

(4)

(5)

valve located at the pump.
0-30 psi (0-206.9 kPa) pressure gauge to measure housing pressure.

0-30 in. Hg (0-101.3 kPa) vacuum gauge to measure transfer pump lift. This gauge should be in
the supply line to the pump, with a shutoff valve between the gauge and the oil source.

A flowmeter for measuring return oil should be used with a three-way valve to permit the

flowmeter to be in use only during the return oil check.

0°-250°F (-17.8°-121.1°C) temperature gauge, located at the pump inlet, to monitor inlet
temperature.

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2-35. (6.5L) FUEL INJECTION PUMP (DB2831-5149) 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 0.098-in. (2.5 mm) inside diameter by 25 in. (63.5 cm) long injection lines.

(f) Calibrating fluid conforming to SAE J967, maintaing 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.

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)
(2)
(3)
(4)

(5)
(6)
(7)

Draw
Settle 30 seconds
Drain 30 seconds
Draw

Settle 30 seconds
Read graduates

Repeat cycle and average readings

2-35. (6.5L) FUEL INJECTION PUMP (DB2831-5149) CALIBRATION (Cont’d)

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

THROTTLE

CAM MOVEMENT

PRESSURE

RPM

POSITION

STROKE*

(DEGREES)

TRANSFER PUMP

HOUSING

150

Low idle

27 min.

0-12 psi (0-83 kPa)

400

WOT

43 min.

400

WOT**

4 max.

700

Low idle

12-16***

0.5 min.

8-12 psi (55-83 kPa)

700

Low idle

****

0-1 psi (0-7 kPa)**

2000

WOT

56 max.

3200

ADJ

21.5-23.5

3.75-16.25

3400

WOT

48-53

3.00-5.00

3500

WOT

43 min.

3650

WOT

30 min.

3900

WOT

15 max.

* Maximum cylinder variation should be ± 6 mm

from the average flow of all cylinders.

** With electric shut-off solenoid de-energized.

*** Reset using low idle screw.

**** Minimum of 1.25 degrees more than reading.

10. Disconnect pump and mount in holding fixture.
11. Using air timing gauge, check pump timing. Set to -2.0 to +0.0 degrees.
12. Total throttle travel from low idle to wide-open throttle should be 75-84 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 1.968 ± .001 in. (49.99 ± .025 mm). With oversize cam ring

installed, roller-to-roller dimension will be 1.976 ± .001 in. (50.19 ± .025 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) Mount the pump horizontally in holding fixture and remove governor cover.
(b) 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.

the vertical tab on the linkage hook.

(d) 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).

(e) 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.

(f) With the linkage hook pin seated firmly in the governor arm slot and the governor arm in

the minimal 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).

(g) Recheck linkage gap and adjust if necessary.

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2-35. (6.5L) FUEL INJECTION PUMP (DB2831-5149) CALIBRATION (Cont’d)

4.
5.

6.
7.

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 1000 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 (414-427 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 3400 rpm (WOT), rotate face cam to its maximum lift position in contact with the cam roller.
Adjust trimmer screw at 3400 rpm (WOT), for 4.0 degrees cam advance and set fuel delivery to

50-51 mm

/troke.

Set guide stud for 35.5-37.5 mm

/stroke at 3650 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

/stroke at 3200 rpm and rotate face cam to obtain 5.10 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 bit 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
75-84 degrees.

NOTE

Any changes to pump or settings after this point will require

retesting of pump, starting with step 12.

2-139

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