ARMY TM 9-2815-256-24
AIR FORCE TO 38G1-96-2
MARINE CORPS TM 2815-24/5
Open gage valve and raise pressure to a point where gage needle falls rapidly. This is nozzle opening pressure,
and should be a minimum of 3330 psi (23,000 kPa) for a used nozzle and 3650 to 3750 psi (25,100 to 25,800
kPa) for a new nozzle.
c. If nozzle opening pressure is not within specified range, replace injector, refer to paragraph 3-29.4.
3-29.3.3 Chatter and Spray Pattern Test.
Check nozzle chatter as follows:
Operate nozzle tester at a pumping rate that will cause nozzle to chatter.
Nozzle should chatter softly, and spray pattern should be broad and finely atomized.
Until the chattering range is reached, fuel will emerge in non-atomized streams.
Using pumping rate for proper atomization, refer to paragraph 3-29.3.1, step c., operate tester for ten
strokes. The nozzle must atomize on at least eight of the ten strokes without consecutive misses.
If nozzle fails to meet this requirement, repeat procedure. Nozzles which do not meet requirement after
second test should be replaced.
Check Spray Pattern.
Operate nozzle tester at a pumping rate that will cause the nozzle to chatter.
Observe spray pattern and check for plugged orifices. Partially clogged, chipped, or eroded orifices will
cause the spray to deviate from correct angle. Spray will be streaky, rather than finely atomized.
If nozzle fails to spray properly, replace it.
3-29.3.4 Leakage Test.
Check nozzle for fuel leakage past valve seat as follows:
Position nozzle on nozzle tester with nozzle tip down.
Operate pump handle rapidly to firmly seat valve.
Raise pressure at nozzle to about 400 to 500 psi (2800 to 3500 kPa) under specified opening pressure.
Watch for an accumulation of fuel around the nozzle orifices.
If fuel drips from nozzle within 5 seconds, nozzle is considered defective, and must be replaced.
Check nozzle for valve stem and guide wear as follows:
Position nozzle with tip slightly above the horizontal plane.
Place a clear, protective shield around spray zone to avoid possible personal injury from spray.
Raise pressure to 1500 psi (10,300 kPa) on test gage.
Look for leakage from return end of nozzle.
After one drop, leakage should be 3 to 10 drops in 30 seconds. Rate based on use of No. 2 diesel fuel or
an equivalent viscosity of test oil at 65 to 75°F (18 to 24°C) ambient temperature.
If nozzle leakage is not within specified range, nozzle must be replaced.