TM 5-3820-233-35/1
the studs. Torque new studs to 25-40 foot-
sembly and recheck the follower return. Re-
place if necessary.
pounds.
(4) Install the injector assembly in the
stall the exhaust manifold.
injector test fixture. Position the control rack
(1) Install new exhaust flange and ex-
in the full fuel position and check each
haust manifold gaskets.
nozzle tip orifice for equal fuel discharge
pressure. T h e p r e s s u r e s h o u l d b e f r o m 4 5 0
(2) Torque manifold attaching nuts to
to 850 psi. Valve opening pressure below 450
30-35 foot-pounds.
psi indicates a defective spring. Replace a de-
(3) Refer to the Operator's Manual and
fective spring or the injector assembly.
(5) Dry the injector assembly with a
outlet flange nuts to 20-25 foot-pounds.
clean, lint-free cloth. Establish pressure on
the injector just below the injector opening
40. Fuel Injector
pressure and close the pump valve. Check the
a. General. A fuel injector assembly is lo-
time required for the pressure to drop from
cated in each of the four cylinders. The fuel
450 to 250 psi. This time should not be less
injector creates the high fuel pressure re-
than 40 seconds. If time is less than minimum
quired for efficient injection, meters and in-
stated above, inspect the injector assembly
jects the exact amount of fuel required to
for moist areas and determine source of leaks.
handle the load on the engine, atomizes the
Leakage around the seal indicates a loose re-
fuel for mixing with the air in the combustion
taining nut. Leakage at the rack opening in
chamber, and permits continuous fuel flow.
the injector.
b. Removal. Refer to the Operator's Man-
d. Disassembly. Disassemble fuel injector
ual.
assembly in the numerical sequence as illus-
c. Bench Testing
trated in figure 17.
(1) Test the spray tip runout with a
e. Cleaning, Inspection, and Repair
dial indicator. Total runout must not exceed
(1) Clean the fuel injector parts with an
0.008 inch. If the runout exceeds 0.008 inch,
approved cleaning solvent and dry thorough-
loosen retaining nut and recenter nozzle tip
ly.
in the nut. Tighten nut and recheck runout.
(2) Inspect teeth on the control rack and
Repeat the procedure until correct runout is
the control rack gear for wear of other dam-
obtained.
age. Replace a defective control rack or con-
(2) Hold the injector assembly in a
trol rack gear.
horizontal position with the coupling end of
(3) Test the follower spring compres-
the control rack pointing upward. Quickly
sion. When a 48 pound load is applied, the
invert the injector assembly so the coupling
spring should compress to a length of 1.028
end points downward. The rack should move
inch. Replace a defective or worn follower
freely through its full travel by its own
spring.
weight. To correct improper rack travel, loos-
(4) Inspect all injector parts for wear
en the retaining nut, rotate the tip assembly,
and damage.
tighten nut, and recheck rack travel. Repeat
(5) Inspect the seating surfaces of the
procedure until proper freedom of travel is
injector body, bushing, valve seat, injector
attained.
valve, valve spring, stop valve, valve cage,
(3) Install the injector assembly in a
check valve, and spray tip with a magnifying
holding device with the top side up. Position
glass, If any imperfections are observed, lap
the control rack in the full fuel position, no
the sealing surfaces using 600 grit dry lap-
fuel position, and midway between. Depress
ping powder.
the follower release, and check for free re-
( 6 ) B e f o r e reassembling
used
valve
turning of the follower with the rack in each
parts in the injector, lap all of the seating
position. To correct the lack of free return,
surfaces indicated in step 5 above.
disassemble and reassemble the injector as-
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