TM 5-3810-300-24&P-3
Fuel Injector
2.1.1
or scratches.
Also check the surface which contacts the
injector bushing for scratches, scuff marks or other
damage. If necessary, lap this surface. A faulty sealing
surface at this point will result in high fuel consumption
loose injector body plugs or a loose dowel pin. Install the
proper number tag on a service replacement injector
body.
Inspect the injector plunger and bushing for scoring,
erosion, chipping or wear. Check for sharp edges on
that portion of the plunger which rides in the gear.
Remove any sharp edges with a 500 grit stone. Wash
the plunger after stoning it. Injector Bushing Inspectalite
J 21471 can be used to check the port holes in the inner
diameter of the bushing for cracks or chipping. Slip the
plunger into the bushing and check for free movement.
Replace the plunger and bushing as an assembly if any
of the above damage is noted, since they are mated
parts. Use new mated factory parts to assure the best
performance from the injector.
Injector plungers cannot be reworked to change the
output. Grinding will destroy the hardened case at the
helix and result in chipping and seizure or scoring of the
plunger.
Examine the spray tip seating surface of the injector nut
and spray tip for nicks, burrs, erosion or brinelling.
Reseat the surface or replace the nut or tip if it is
severely damaged.
The injector valve spring plays an important part in
establishing the valve opening pressure of the injector
Fig. 37 - Injector Plunger, Follower and Relative Location
assembly. Replace a worn or broken spring.
of Parts
Inspect the sealing surfaces of the injector parts
material can prevent the needle valve from seating
indicated by arrows in Fig. 31. Examine the sealing
properly. Polish the seat area with polishing stick J
surfaces with a magnifying glass as shown in Fig. 32 for
22964. Coat only the tapered end of the stick with
even the slightest imperfections will prevent the injector
polishing compound J 23038 and insert it directly into the
from operating properly. Check for burrs, nicks, erosion,
center of the spray tip until it bottoms. Rotate the stick 6
cracks, chipping and excessive wear. Also check for
to 12 times, applying a light pressure with the thumb and
enlarged orifices in the spray tip. Replace damaged or
forefinger.
excessively worn parts. Check the minimum thickness
of the lapped parts as noted in the chart.
Minimum
Examine the seating area of the needle valve for wear or
Part Name
Thickness
damage. Also examine the needle quill and its contact
Spray Tip (shoulder)
199"
point with the valve spring seat. Replace damaged or
Check Valve Cage
.165"-.163"
Check Valve
022"
excessively worn parts.
Valve Spring Cage
602"
Examine the needle valve seat area in the spray tip for
TABLE 1 - Minimum Thickness (Used Parts)
foreign material. The smallest particle of such
Page 174