TM 9-2815-225-34&P 3-52. FUEL INJECTOR REPAIR (Contd) LOCATION/ITEM ACTION REMARKS c.  Inspection (Contd) CAUTION The injector plunger must seat in cup from 1/4 of upper cone area to full cone area.  Reject a cup that seats in lower 14 cup tip area.  If a cup seats in the tip area, it must seat more than 1/2 of cone area to be accepted. d.  Plunger seat pattern.   Using new injector plunger (2), coat with Prussian blue and rotate 90. If 40 percent continuous coverage is maintained, it may be reused but must pass the cup-to-plunger test. 15. Cup retainer (11) Inspect for a.  Damaged threads. b.  Nicks and burrs on outside Nicks and burrs will prevent heat seating area and inside proper seating. seating ledge. NOTE If injector passes leakage test, barrel is usable.  If leakage is high, barrel and plunger must be replaced. 16. Barrel (9) Inspect for: a.  Scoring of bore area. b.  Burrs, carbon, and distorted radius in the orifice. c.  Loose or cracked fuel passage plugs. d.  Damage and flatness at mating Lap with a grade A 280-grit surfaces. lapping compound to remove mutilation or unevenness.  Use a surface plate to check surface flat- ness. 17. Check ball (12) and Inspect for: ball seat a.  Nicks and burrs on ball (12). Discard if burred or nicked. b.  Depth of ball seat. Maximum is 0.050 in.  (1.27 mm) below surface of barrel (9). 18. Top-stop adapter (7) Inspect for: a.  Burrs or obstructions around Discard if unable to remove. orifice. b.  Obstructions in fuel passage Clean. openings. c.  Damaged threads. Rethread. d.  Gasket area for nicks or burrs. Remove nicks or burrs, or gaskets (8) will be damaged. e.  Mating surface for nicks or Discard if unable to remove. burs. f.  Damage and flatness at mating surfaces. 3-346