TM 5-3895-346-14
ENGINE OVERHAUL
FUEL INJECTOR
3. Position the injector rack in the full-fuel position.
4. Place pump lever 1 in the vertical position.
5. Move lever 3 to the forward detent position.
6. The injector follower should be depressed rapidly (at 40 to 80 strokes-per-minute) to simulate operation in
the engine. Observe the spray pattern to see that all spray orifices are open and dispersing the test oil evenly.
The beginning and ending of injection should be sharp and the test oil should be finely atomized with no drops
of test oil forming on the end of the tip.
The highest pressure reference number shown on gage 2 will be reached just before injection ends. Use the
following reference values to determine the relative acceptability of the injector. Reference values for Series
53 injectors are from 127 minimum to 146 maximum, except the L-40 injector which is from 116 minimum to
127 maximum.
NOTE
The reference value obtained when pop testing the needle valve injectors is to be used as a
troubleshooting and diagnosis aid. This allows comparative testing of injectors without
disassembly. Exact valve opening pressure values can only be determined by the Needle Valve
Tip Test using tester J 23010 and tip test adaptor J 23010-129, or auxiliary tester J 22640.
Injector High-Pressure Test
This test checks for leaks at the filter cap gaskets, body plugs, and nut seal ring.
1. Clamp the injector properly and purge the air from the system.
2. Close the thru-flow valve, but do not overtighten.
NOTE
Make sure lever 4 is in the down position before operating pump lever 1.
3. Operate pump lever 1 to build up to 1600 to 2000 psi (11 024 to 13 780 kPa) on gage 1. Check for leakage
at the injector filter cap gaskets, body plugs, and injector nut seal ring.
Injector Pressure Holding Test
This test determines if the body-to-bushing mating surfaces in the injector are sealing properly and indicates
proper plunger-to-bushing fit.
1. Clamp the injector properly and purge the air from the system.
2. Close the thru-flow valve, but do not overtighten.
3. Move lever 2 to the rear, horizontal position.
4. Operate pump lever 1 until gage 1 reads approximately 700 psi (4 823 kPa).
5. Move lever 4 to the up position.
6. Time the pressure drop between 450 to 250 psi (3 100 to 1 723 kPa). If the pressure drop occurs in less
than 15 seconds, leakage is excessive.
Refer to the Troubleshooting Charts if the fuel injector does not pass any of the preceding tests.
If the fuel injector passes all of the above tests, proceed with the Fuel Output Test.
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