GMC 4000 Series Service Manual page 378

may be necessary to tap lightly only with plastic
hammer on fuel lines.
3. Clean all dirt from around injection nozzle
holder depression in cylinder head. Use screw ­
driver blade to force leak-off hose off fitting in top
of nozzle holder. Remove the two nozzle holder
bolts amd lock washers, then pull nozzle holder
assembly out of cylinder head, meanwhile using
air hose to blow away any dirt particles which may
be loosened as the nozzle holder is lifted out.
4. If necessary, use a suitable hook to remove
copper gasket from bottom of cavity in cylinder
head. Plug the opening cylinder head.
INSPECTION BEFORE DISASSEMBLY
NOTE: Test each nozzle assembly for leakage,
valve opening pressure and spray pattern before
disassem bly. If nozzle assembly is in good condi­
tion, it should not be disassembled, but should only
be cleaned externally. If holes in nozzle tip are
clogged as indicated by unsatisfactory spray pat­
tern, the components shouldbe disassem bledbefore
attempting to clean holes.
1 Spring
2 Cap Gasket
3 Pressure Adjusting Nut
4 Cap Nut
5 Leak-off Line Tee
6 Spindle
7 Nozzle Holder
8 Valve
9 Valve Body
10 Nozzle Cap Nut
11 Gasket (Copper)
G M C S E R V I C E M A N U A L
FUEL INJECTION SYSTEM— TORO-FLOW ENGINE
Figure 1 9 — Nozzle H older a n d V a lve A sse m b ly Com ponents
REFER TO "SETTING INJECTION NOZZLE
VALVE OPENING PRESSURE" FOR NOZZLE TEST
PROCEDURE.
DISASSEMBLY (Fig. 19)
1. Extreme care must be exercised in handling
nozzles and components. Do not allow nozzle tip to
strike against other parts or tools as holes in tip
may be damaged or tip may be deformed or broken.
2. With nozzle holder mounted on fixture or
held in vise, loosen cap nut (4) and remove nut and
gasket from spring pressure adjusting nut (3).
3. With Allen wrench, remove spring pressure
adjusting nut from nozzle holder (7). Remove spring
(1) and spindle (6).
IMPORTANT: DO NOT PROCEED WITH STEP
4 UNLESS ADJUSTING NUT (3) HAS BEEN LOOS­
ENED TO RELIEVE THE SPRING PRESSURE.
4. Invert nozzle holder and remove the nozzle
cap nut (10) from nozzle holder (7), then separate
valve body (8 and 9) from the nozzle holder.
Sec. 6M
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