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TM 10-3930-643-34
ENGINE, FUEL, EXHAUST AND COOLING TROUBLESHOOTING AND MAINTENANCE.
4-12.
Fuel Injectors. (Sheet 3 of 5)
TESTING/CLEANING/INSPECTION
3.
4.
5.
6.
7.
Operate test pump until nozzle
opening pressure is reached.
All
orifices in nozzle tip
should be
clear. Fuel should spray in atomized
mist. Nozzle should emit a
sharp
high-pitched chatter.
If chattering
does not occur, flush with pump in
rapid complete
strokes.
Spray
pattern should be uniform and equal
in all directions.
Operate test pump a few strokes to
clear air from nozzle.
Raise
pressure steadily. Observe pressure
at which nozzle
opens.
Opening
pressure for new nozzles is 3600 to
3750 psi.
Minimum opening pressure
for used nozzles is 2900 psi.
Wipe nozzle tip dry. Bring pressure
slowly to 500 psi
below
nozzle
opening pressure.
Maintain this
pressure for 5 seconds. Wetting of
nozzle
is permissible
without
formation of a droplet. Do not wipe
the tip with fingers.
This will draw
fuel present in sac hole through
orifices
and give
false leak
indication.
Hold wiper lightly
against tip of nozzle.
Bring pressure on nozzle to 1500 psi.
Collect any leakage from fuel return
stem.
Maximum allowable leakage is
1.5 cubic inch in one minute.
Wipe retainers (4) with a damp clean
cloth using a mild detergent and
water solution.
Go to sheet 4
4-85
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