TM 9-4310-397-14
6-3. FUEL INJECTION NOZZLE REPAIR AND REPLACEMENT. - Continued
(3).
Pump tester handle (8) five strokes to flush air from lines and fittings and to determine the pumping rate required
for proper atomization. Tighten all connections securely.
WARNING
If injured by escaping fluid, see a doctor at once. Serious infection or reaction can develop if
proper medical treatment is not administered immediately.
(4) Isolate test pump gauge by closing valve and flush nozzle by operating test pump rapidly.
(5) Opening pressure test.
NOTE
Actual opening pressure is less important than equal opening pressure of a l l nozzles.
Permissible variation is 100 psi (700 kPa) (7 bar) difference between cylinders (nozzles).
(a) Actuate the nozzle tester rapidly several times to allow the valve to seat rapidly.
(b) Open gauge valve (9) and raise the pressure to a point where the gauge needle falls rapidly. This is the
nozzle opening pressure. A new or reconditioned nozzle should be: 3150-3250 psi (21700-22400 kPa)
(217-224-bar). A used nozzle should have a minimum opening pressure of 3000 psi (20700 kPa) (207
bar).
(c) If the nozzle opening pressure is not within specified range. Adjust nozzle BEFORE checking chatter and
spray pattern.
(6) Chatter and spray pattern test.
(a) Check nozzle chatter.
NOTE
Until the chattering range is reached, fuel will emerge in non-atomized streams.
1 Operate nozzle tester at a pumping rate that will cause the nozzle to chatter. Nozzle should chatter
softly, and spray pattern should be broad and finely atomized.
2 Using the pumping rate for proper atomization operate tester for ten strokes. (See step (3)). The
nozzle must atomize on at least eight of the ten strokes without consecutive misses.
3 If the nozzle fails to meet this requirement, repeat procedure. Nozzles which do not meet the
requirement after second test should be replaced.
(b) Check spray pattern.
1 Operate nozzle tester at a pumping rate that will cause the nozzle to chatter.
2 Observe spray pattern and check for plugged orifices, partially clogged, chipped, or corroded orifices
will cause the spray to deviate from the correct angle.
3 Spray will be streaky, rather than finely atomized. Replace nozzle if found bad.
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