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TM 10-3930-671-24
Fuel Injector Testing
WARNING
Bodily Injury may result during this procedure if
care is not taken. Keep hands and face away
from nozzle spray. The high velocity of oil spray
may
puncture
the
skin
and
cause
blood
poisoning. If injured by escaping fluid, get
medical attention at once.
NOTE
Injection should not be disassembled unless
testing shows that cleaning or other servicing Is
needed.
Injectors are tested by using a special hydraulic injector
tester, bolted to a bench with a small fuel oil supply tank
with filter included to ensure that only clean fuel enters
the injector. A high-pressure injection line is used to
connect the outlet of the tester to the injector.
NOTE
The Injector test gauge should not be subjected
to shock pressure. Keep the gauge valve open
only when reading pressure.
1.
Close gauge valve and work pump handle
several sharp strokes to dislodge any carbon or
dirt particles in nozzle cavities.
2.
Open gauge valve, work pump slowly, and
observe
nozzle
opening
pressure.
(Specification: 2050-2130 psi). If opening
pressure is not correct, remove nozzle from
nozzle holder and shim as required to obtain
2050-2130 psi. If shims are not available,
replace nozzle.
NOTE
It is desirable to have all injectors set as nearly
alike
as
possible
in
the
same
engine.
3.
Maintain a pressure of 2050-2130 psi and
watch for dribble from spray orifice, indicating a bad
seat; or "weeping" around cap nut, indicating a leak
between the holder and valve body lapped surfaces.
4.
Close
gauge
valve
and
observe
spray
characteristics while working the tester about
100 strokes per minute. "Flags," heavy ends,
deflected core, or a spray pattern that is not
symmetrical are undesirable. Repair or replace
faulty parts as necessary. A target 12" from the
nozzle end, with bullseye level with pintle will
show any deflection of spray pattern.
F-205
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