GMC 4000 Series Service Manual page 374

mark on crankshaft damper is aligned with pointer
in engine front cover (fig. 11). At this point pump
should be injecting fuel into No. 1 cylinder, which
will be the case if alignment marks are aligned as
explained in following Step 4.
4. If engine is correctly timed, the mark and
pointer (9 and 8, fig. 10) will be indexed and mark
(4, fig. 10) on face gear viewed through cover open­
ing in pump housing will be in the position shown
in the inset in figure 10.
5. If the mark on pump drive hub is not index­
ed with pointer, or if the mark on face gear is not
visible in opening, the injection timing is not cor­
rect. Before proceeding to reset the injection tim ­
ing be sure No. 1 piston is on compression stroke
and "INJ" mark on damper is aligned with pointer
(fig. 11).
SETTING INJECTION TIMING
The elongated holes in injection pump driven
gear (fig. 12) make possible the setting of injection
timing when installing the fuel injection pump a s­
sembly as well as for making correction of timing
when necessary.
1. With engine crankshaft positioned for firing
on No. 1 cylinder (refer to Steps 3 and 4, under
"Checking Injection Timing" previously) use a 7 /8 -
inch wrench and 9/16-inch box end wrench as
shown in figure 13 to loosen three driven gear
mounting bolts (6, fig. 13).
SUGGESTION: With engine in time, two bolts
at the top can be loosened with 9 /1 6 -inch box end
wrench and third bolt at the bottom can be loosened
with 9/16-inch open-end wrench.
2. With bolts (6, fig. 13) loose, and engine in
time, as in Step 1 previously, use 7/8-inch wrench
to turn injection pump shaft and hub as necessary
to align mark on hub with pointer (3, fig. 13). Hold
the shaft with wrench and tighten driven gear mount­
ing bolts.
NOTE: Proper torque for driven gear mount­
ing bolts is 35 to 40 foot-pounds with oiled threads.
3. After fuel injection pump gear mounting
bolts are tightened, turn engine over slowly to bring
timing marks into alignment as previously explain­
ed. Recheck indexing of marks.
GOVERNOR SPRING ADJUSTMENT
In cases where symptoms indicate defective,
broken, or improperly adjusted governor springs,
the following procedures are required to inspect
and/or adjust the governor inner and outer spring.
One (first) procedure can be used in case the spec­
ially designed gauge is not available; however, the
second procedure using the gauge designed for this
purpose is preferable for adjustment. Symptoms
which are indications of governor spring malfunc­
tion are included under appropriate headings in
"Fuel System Trouble Diagnosis" at end of section.
G M C S E R V I C E M A N U A L
FUEL INJECTION SYSTEM— TORO-FLOW ENGINE
speeds depend almost entirely on the characteris­
tics of the governor springs, hence the speeds can
only be varied to a limited degree by the adjusting
screw s at rear of governor housing (fig. 14).
equipment to gain access to fuel injection pump.
INTERNAL GOVERNOR SPRING PACK
ADJUSTMENT (WITHOUT SPECIAL TOOL)
nor cover to top of governor housing, then remove
cover and gasket.
Figure 12— Injection Pum p Driven Gear
and Pum p M o un ting Studs
IMPORTANT: The normal idle and maximum
NOTE: Remove air cleaner and necessary
1. Remove the four bolts attaching the gover­
1 Holding Pump Shaft
2 Fuel Injection Pump
3 P ointer
4 D riven Gear Mounting
5 Injection Pump Driven
6 D riven Gear Mounting
7 Hub Retaining Nut
8 Tightening D riven Gear
Figure 13— Using Wrench to Hold Pum p Shaft
W hile Tightening Drive Gear Bolts
Sec. 6M
Page 363
With 7/8" Box W rench
A ssem bly
Hub
Gear
B olts
Bolt With 9/1 6 " Box
Wrench
T-55 59