TM 5-3895-346-14
FUEL INJECTOR
ENGINE OVERHAUL
4. If the needle valve lift is within limits, install a
new needle valve spring and recheck the valve
opening pressure and valve action. Low valve
opening pressure or poor atomization with a new
spring and seat indicates the spray tip and
needle valve assembly should be replaced.
5. Reassemble the injector as outlined under
Assemble Injector and check the injector output
with calibrator J 22410.
Needle Valve Tip Test (Using Auxiliary
Tester J 22640)
1. Connect the pipe from auxiliary tester J
22640 to the rear of the J 23010 tester at the
connection located near the bottom of the tester
(Fig. 17).
2. Assemble cleaned injector parts, including
Figure 16. Checking Needle Valve Lift with
the check valve cage, spring, spring seat, spring
Tool J 9462-02
cage, and spray tip assembly, on auxiliary tester
J 22640 (Fig. 18).
3. Carefully pilot the injector nut over the spray tip and valve parts and thread it on the auxiliary tester.
4. Tighten the injector nut.
5. Open the valve on the auxiliary tester and place lever 4 in the up (horizontal) position.
6. Install the shield on the auxiliary tester and operate pump lever 1 until the needle valve has opened several
times to purge the air from the system.
7. Operate pump lever 1 rapidly with smooth even strokes (40 strokes-per- minute) simulating the action of the
tip functioning in the engine. Note the pressure at which the test oil delivery occurs. Test oil delivery should
occur between 2200 and 3200 psi (15 158 and 22 048 kPa) except for the L-40 injector which should open
between 1700 and 2300 psi (11 713 and 15 847 kPa). The beginning and ending of delivery should be sharp
and the test oil should be a finely atomized spray.
If the valve opening pressure is below 2200 psi (15 158 kPa) or 1700 psi (11 713 kPa) for the L-40 injector
and/or atomization is poor, the cause is usually a weak valve spring or poor needle valve seat.
If the valve opening pressure is within 2200-3200 psi (15 158-22 048 kPa) or 1700-2300 psi (11 713-15 847
KPa) for the L-40 injector, proceed to check for spray tip leakage as follows:
NOTE
When testing for spray tip leakage using the auxiliary tester, be sure to use the proper spring for
the valve tip being tested.
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