2-34. 1990 (6.2L) FUEL INJECTION PUMP (DB2829-4879) CALIBRATION (Contd)
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 mm3/stroke at 650 rpm (fuel reading with cover installed).
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 mm3/stroke for the remainder of the setting and checking
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
Set guide stud for 35-37 mm3/stroke at 3800 rpm (WOT). Tighten guide stud nut to 80-90 lb-in.
(9-10 Nm) and check dimension from top of nut to top of guide stud for 0.400-in. (10.2 mm)
Set throttle for 21.5-23.5 mm3/troke at 1500 rpm and rotate face cam to obtain 2.25 degrees cam
Tighten face cam screw to 28-30 lb-in. (3 Nm) 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 Nm) 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
Any changes to pump or settings after this point will require
retesting of pump, starting with step 12.