GMC 4000 Series Service Manual page 377

Sec. 6M
Page 366
FUEL INJECTION SYSTEM— TORO-FLOW ENGINE
SPECIAL TOOL
STOP LEVER
Figure 18— Special Tool Application for Selecting
Outer (Low Speed) Spring Spacer
5. Remove inner spring, guide, and spacers
(7, 5, and 6) from the governor shaft, keeping these
parts together so they can be reinstalled after outer
spring spacer selection has been made.
6. Assem ble outer spring spacers (4), removed
at disassem bly, and the outer spring (3) at recess
in center of the governor sleeve (8).
7. Place outer spring guide (2) over pilot on
special tool (fig. 18), then place tool assembly at
governor housing with pilot entered into outer
spring. Governor sleeve (8) must be held forward
as far as possible (fig. 16).
8. Observe outer spring clearance with feeler
gauge on tool to determine if spacers are to be
removed or added and in what thickness (fig. 18).
The outer spring can be turned but has no end play.
9. Remove the outer spring (3), guide (2) and
the tool components which are removable from
tool mounting flange.
10. Add or remove spacers (4) as necessary
to position the tool clearance to proper outer
spring adjustment. Tool clearance will indicate
outer spring compression of 0.059 to 0.069 inch
when proper spacers are in place (fig. 18).
NOTE: When spring spacer selection has been
completed, remove the tool assembly using care
to take note of spacers selected so same pack can
be reinstalled.
11. Perform Steps 7 through 12 previously
under "Internal Governor Spring Pack Adjustment
(Without Special Tool)" in this section.
G M C S E R V I C E M A N U A L
BACK OUT IDLE ADJUSTING
SCREW IF NECESSARY
HIGH SPEED
SCREW
OPERATING
(THROTTLE)
LEVER
G O V ER N O R SLEEVE
FUEL INJECTION NOZZLES
LOCATING A MISFIRING CYLINDER
The procedure which follows may be used to
locate a misfiring cylinder which may result from
defective injection nozzle assembly.
This procedure will not serve to detect a noz­
zle with incorrect popping pressure within a mod­
erate range. Such a malfunction can only be deter­
mined by removal of nozzle assembly from engine
and checking on test stand (fig. 22).
1. Connect an accurate tachometer at the tach­
ometer drive fitting on engine.
2. With engine running at 1,000 rpm, observe
the tachometer reading as high pressure line nut
is loosened at injection nozzle holders. When a
high pressure line nut is loosened, the pressure
build-up will not be great enough to cause the noz­
zle to deliver fuel to the cylinder being tested and
no power will result. If, when the line nut is loos­
ened, the engine rpm drops approximately 300 rpm,
it can be assumed that the cylinder is functioning
normally. On the other hand, if there is little or
no drop in engine rpm when the line nut is loosened,
the nozzle may be at fault and it should be removed
for cleaning and inspection. Tighten line nut to 20
to 25 foot-pounds torque.
NOTE: When nut is loosened, fuel will spill
from the loosened nut with each discharge from
injection pump port. A shop towel around the nut
will absorb spillage. Also, when nut is loosened to
break seal at line connector it may be necessary
to tap lightly only with plastic hammer on fuel lines.
NOZZLE AND HOLDER ASSEMBLY
MAINTENANCE
Normally, unless engine performance, or other
trouble diagnosis symptoms indicate a malfunction
of fuel injection nozzles, the nozzle and holder a s­
sem blies should not be removed from engine.
When it becomes necessary to remove nozzle
and holder assem blies use injection nozzle service
tool set (J-2176-01). Follow the procedures given
below:
REMOVING NOZZLE AND
HOLDER ASSEMBLIES
1. Disconnect the high pressure line nut at
the fuel injection nozzle holder and at fuel injec­
tion pump hydraulic head.
2. Remove the clamp assembly (fig. 27) from
line being removed, then remove the highpressure
line, using care not to bend line.
IMPORTANT: High pressure line must be d is­
connected at both ends and clamp must be removed
so line can be removed without bending. Install
dust caps when line is removed.
NOTE: To break seal at line connectors it