TM 5-3895-346-14
ENGINE OVERHAUL
FUEL INJECTOR
NOTE
Use the fuel injector clamping procedure to
clamp adaptor J 23010-167 in the injector tester.
Spray Tip Test
1. Move lever 4 down and operate pump lever
1 rapidly with smooth, even strokes (40 strokes
per minute), simulating the action of the tip
functioning in the engine (Fig. 13).
2. Note the pressure at which the needle valve
opens on gage 1. The valve should open
between 2200 and 3200 psi (15 158 and 22 048
kPa). The opening and closing action should be
sharp and produce a normal, finely atomized
spray pattern.
If the valve opening pressure is below 2200 psi
(15 158 kPa) and/or atomization is poor, the
cause is usually a weak valve spring or a poor
needle valve seat.
If the valve opening pressure is within 2200-
Figure 15. Adaptor and Tube
3200 psi (15 158-22 048 kPa) or 1700-2300 psi
Assembly on Injector Tester J23010
(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.
a. Actuate pump lever 1 several times and hold the pressure at 1500 psi (10 335 kPa) for 15 seconds.
b. Inspect the spray tip for leakage. There should be no fuel droplets, although a slight wetting at the spray tip
is permissible.
Needle Valve Lift Test
To measure the needle valve lift, use tool J 9462-01 (Fig. 16) as follows:
1. Zero the indicator by placing the bottom surface of the plunger assembly on a flat surface and zero the
indicator dial.
2. Place the spray tip and needle valve assembly tight against the bottom of the gage with the quill of the
needle valve in the hole in the plunger.
3. While holding the spray tip and needle valve assembly tight against the gage, read the needle valve lift on
the indicator. The lift should be 0.008 to 0.018 inch. If it exceeds 0.018 inch, the tip assembly must be
replaced. If it is less than 0.008 inch, inspect for foreign material between the needle valve and the tip seat.
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