GMC 4000 Series Service Manual page 379

Sec. 6M
Page 368
FUEL INJECTION SYSTEM— TORO-FLOW ENGINE
N EEDLE H O LD ER
O RIFICE NEEDLE
Figure 2 0 — C leaning Spray Holes in Nozzle
CAUTION: Valve (8) and valve body
(9) constitute a matched pair which must
be used as such. When handling injection
nozzle valve, do not touch valve finished
surfaces with fingers. Wash parts in clean
fuel oil and polish with clean tissue paper.
CLEANING AND INSPECTION
Clean nozzle tip with a brass wire brush be­
fore disassembling the valve body from nozzle
Figure 21— Use of Centering Sleeve to Locate
Valve Body W hile Tightening Cap Nut
G M C S E R V I C E M A N U A L
V A L V E B O D Y
1 Cup
2 Spray Tip
3 N o z z le H older A ssy
4 Pressure Gauge
5 Fuel High Pressure
Line
Figure 2 2 — Test Stand for Checking Injection
Nozzle Operation
holder. Clean the nozzle tip orifices using orifice
needle (part of kit J-21761-01) (fig. 20). Care must
be used when cleaning orifices to avoid breaking
orifice needle in hole, as it is difficult or im poss­
ible to remove broken pieces. After disassembly,
all parts should be carefully cleaned. If lapped
surfaces on holder and mating surface on valve
body are scratched, remove dowel pins from nozzle
holder and polish the surface on lapping block u s­
ing special fine lapping compound. Also, polish the
mating surface on valve body. Install new dowel
pins after nozzle holder surface has been lapped.
ASSEMBLY
Key numbers in text refer to figure 19.
1. Dip valve and body (8 and 9) in clean fuel
and insert valve in body.
NOTE: The valve must be free in the body. By
lifting the valve about one-third of its length out
of the body, the valve should slide back to its seat
without aid when the assem bly is held at a 45-de-
gree angle. If necessary, work valve into the body
with clean mutton tallow.
2. Mount nozzle holder (7) in holding fixture,
then set valve body in place on nozzle holder dowel
pins and screw nozzle cap nut (10) onto nozzle
holder. Before tightening cap nut (10), use center­
ing sleeve (part of kit J-21761-01) (fig. 21) over
nozzle tip to locate the nozzle valve body in center
of opening in cap nut. After nut has been tightened
sufficiently to seat parts, remove centering sleeve
6 Allen Wrench
7 Cap Nut
8 Box End W rench
9 Fixture
10 Pump Handle
11 Test Stand