GMC 4000 Series Service Manual page 389

Sec. 6M
Page 378
FUEL INJECTION SYSTEM— TORO-FLOW ENGINE
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 Steps 4 and 5.
4. If engine is correctly timed, the mark and
pointer (9 and , fig. 10) will be indexed and mark
8
(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 .
1 0
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. ).
1 1
. Remove tubing clamps which are shown in
6
figure 27. Use the adapter shown in figure 26 and
loosen high pressure tubing nuts at fuel injection
n o z z le s and at pump hydraulic head. U se a ir h o se
to blow away any loose dirt particles at hydraulic
head and at nozzles. With fingers complete tubing
nut removal at both ends of each line, then if nec­
essary, to break seal tap fuel line lightly with plas­
tic hammer. Remove the high pressure tubing,
1 Injection Pump Assembly
2 Fuel Supply Line Fitting
3 Drive Gear
4 Mounting Studs
G M C S E R V I C E M A N U A L
5 Seal Ring
Overflow Valve
6
7 Lubricating Oil Fitting
Figure 3 8 — Installing or Re m oving Fuel Injection Pum p A sse m b ly
using care not to bend tubing. When tubing nuts are
disengaged from threads each line may be readily
removed. Tape ends of each line to keep dirt out.
NOTE: To facilitate installation, eachlinemay
be tagged with identification number corresponding
with cylinder numbers (fig. 27).
7. Plug pump ports and cap fittings at injec­
tion nozzles as soon as lines are removed. Figure
shows caps at injection nozzles and plugs in hy­
6
draulic head ports.
NOTE: THE IMPORTANCE OF CLEANLINESS
CANNOT BE OVER-EMPHASIZED.
. Disconnect fuel leak-off lines from over­
8
flow valve.
9. Disconnect stop control cable and discon­
nect accelerator linkage from lever at left side of
injection pump assembly.
10. Disconnect fuel lines from fittings on sup­
ply pump at rear end of injection pump assembly.
Also, disconnect the fuel line at left side of injec­
tion pump housing. Cap or plug all openings to
prevent entrance of dust.
11. At right side of pump assembly, discon­
nect lubricating oil line and the fuel return line at
the overflow valve assembly.
Pointer
8
9 Mark on Adapter Hub
10 Engine Front Cover
11 Stop Lever
-4529
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