Note. The capnut should be tightened to a torque of e0 to
66 ft-lb
b. Testing.
(1) Before installing on the engine, use a
nozzle testing pump to test each fuel
injector assembly for leakage and opening
pressure.
(2) Connect the fuel injector assembly on the
end of the fuel line or fuel inlet connection
of the testing pump.
Warning: When testing the fuel injector keep hands
away from the nozzle spray. The high velocity of the
fuel oil may puncture the skin and cause blood
poisoning.
(3) Pump the nozzle tester lever with quick
strokes for shock test of the nozzle. Open
the gage valve and pump with steady even
strokes until the gage indicates a pressure
of 1,750 to 1,850 psi. The pintle should pop
open if the opening pressure is correct.
When a new spring has been installed in an
overhauled injector assembly, set the
opening pressure 10 percent above normal
Figure 15. Fuel injector assembly, exploded view.
to allow for spring setting which will occur
within the first 60 hours of operation. If the
b. Inspection and Repair.
pintle opens above 1,860, or below 1,760
psi, adjust the spring pressure. Remove
(1) Inspect the spindle and spring for damage
the adjustment screw cover, and loosen the
or wear. A pitted or corroded spring must
jam-nut.
Turn the adjusting screw
be replaced. Replace all defective parts.
clockwise to raise the opening pressure,
and counterclockwise to lower the opening
pressure. Then tighten the jam-nut. Make
(2) Inspect the holder and be sure all passages
several tests, and set the pressure as
are clean.
precisely as possible. Install the adjusting
screw cover.
(3) Inspect all threaded parts of the fuel injector
for damage to threads. Replace all parts
(4) After adjusting the opening pressure, check
having defective threads.
the spray characteristics while working the
pump at above 100 strokes per minute.
(4) Inspect the metallic seals and gaskets for
The spray must be uniform and of regular
wear and damage. Replace a worn or
pattern, without side streams or deflected
damaged seal or gasket.
direction. A faulty spray is caused by a
dirty or defective nozzle valve.
63. Fuel Injector Assemblies Reassembly, Testing,
and Installation
(5) Test for slow leakage by maintaining the
pressure below 1,750 psi. If there is no
a. Reassembly. Refer to figure 15 and reassemble
discernible leakage when the pressure is
the fuel injector assembly in the reverse order.
held within 1,650-1,900 psi on the gage, the
nozzle is tight.
AGO 8456A
41
