GMC 4000 Series Service Manual page 387

Sec. 6M
Page 376
FUEL INJECTION SYSTEM— TORO-FLOW ENGINE
3. Observe through opening in oil seal the
position of flat in pump gear bore. A clean screw ­
driver may be used to turn the gear so as to align
the gear with flat ( ) on shaft.
2
4. Move supply pump assembly into position
at injection pump housing using care to engage
drive gear with flat on shaft. Install and tighten
supply pump attaching bolts on which lock washers
must be used. Tighten bolts to 5 to
torque.
5. Connect fuel lines to fittings at supply
pump, remove vent plug from top of secondary
fuel filter and bleed air from pump and lines.
REPLACING HYDRAULIC HEAD
ASSEM BLY
Refer to figure 36 for identification of various
item s involved in hydraulic head replacement.
NOTE: The hydraulic head assembly which is
shown in figure 36 is available for service use and
is complete with face gear and plunger. If a new
hydraulic head assembly is required, it will be
necessary to remove the fuel injection pump a s­
sembly from the engine assembly; and the pump
assem bly MUST be recalibrated on equipment de­
signed for this purpose after the service head is
installed. In cases where the hydraulic head is in
satisfactory operating condition, but it becomes
necessary to remove the head assembly to replace
the O-ring seals or other parts of the pump, it is
possible to remove and install the hydraulic head
without removing the pump assembly from the en­
gine. Recalibrating is not required if the head
replacement procedure is followed exactly as
ejqplained under "Removal" and "Installation."
Figure 3 7 — Fuel Injection P u m p C avity with
H yd ra ulic H e a d R e m o v ed (Typical)
G M C S E R V I C E M A N U A L
REMOVAL
access to fuel injection pump assembly and fuel
lines. Use solvent and brush to loosen and remove
any accumulated dirt from pump assembly and fuel
lines and fittings. Clean thoroughly to prevent dirt
from entering fuel system .
lines, then plug or cap the openings in the hydraulic
foot-pounds
6
head and nozzles.
caps for closing the openings in pump and lines
is available for use when working on the pump
and/or lines.
under "Control Unit Assembly Replacement" and
remove injection pump control unit assembly.
ton in firing position with the marking on crank­
shaft damper aligned with pointer (fig.
mark on face gear (visible in inspection window in
pump housing) indexed with mark on housing (fig.
10). Make sure the No. 1 piston is on compression
stroke.
dexed with housing mark, even though damper mark
may not be exactly registered with pointer (fig.
and indexing plate. Remove four socket head
screws and retainers which attach the hydraulic
head to the pump housing (fig. 36).
with a plastic or lead hammer or slightly rotate
the assembly with a wrench on the delivery valve
cap to loosen it in housing bore. Raise the hy­
draulic head assembly up out of the pump housing.
Remove upper seal ring (fig. 36) from groove in
head assem bly. Remove the head lower seal ring
(fig. 37) from bottom of bore in pump housing. DO
NOT TURN ENGINE CRANKSHAFT WHILE HY­
DRAULIC HEAD IS REMOVED FROM PUMP.
INSTALLATION
with petroleum jelly, then place lower ring inp osi­
tion at bottom of bore in pump body as shown in
figure 37.
1. Remove equipment as necessary to provide
2. Disconnect and remove fuel high pressure
NOTE: A service kit, containing all plugs and
3. Refer to the instructions given previously
4. Turn engine crankshaft to place No. 1 p is­
IMPORTANT: Mark on face gear should be in­
a. Remove the head locating screw, gasket,
b. Tap the hydraulic head assembly lightly
CAUTION: If the original hydraulic
head assembly is not reinstalled, it will
be necessary to remove the fuel injection
pump assembly from the engine and to re­
calibrate the pump to "Specifications,"
using equipment designed for this purpose
in the hands of specially trained personnel.
1. Lubricate the hydraulic head O-ring seals
), and the
1 1
).
1 0