Figure 3-20. Fuel injectors, removal and installation.

TM 10-3930-242-34

Figure 3-20. Fuel injectors, removal and installation.

serve spray pattern to see that all spray

(c) Check for leak at injector rack open-

orifaces are open and injecting evenly.

ing. A leak indicates a poor bushing-to-body fit.

The beginning and ending of injection

(d) A leak around spray tip or seal ring

should be sharp and fuel injection should

usually is caused by a loose injector nut, a dam-

be finely atomized.

a g e d seal ring, or a rough surface on injector

nut or spray tip.

(3) Spray pattern test. Mount injector in the

(e) A leak at filter cap indicates a loose

t e s t e r . Place the injector rack in the full fuel

filter cap or a damaged filter cap gasket.

position and operate the pump handle until fuel

(f) A "Dribble" at the spray tip orifaces

p r e s s u r e is 200-250 psi; then close fuel shutoff

indicates a leaking valve assembly due to a

valve.

d a m a g e d surface or dirt.

(4) Visual inspection of plunger. An injector

CAUTION

w h i c h passes the previous test should have the

To prevent damage to the pressure gage,

p l u n g e r checked visually, under a magnifying

do not exceed 250 psi during test. Oper-

g l a s s , for excessive wear or a possible chip on

t h e bottom helix. There is a small area on the

ate injector several times in succession

bottom helix and lower portion of upper helix, if

by operating tester handle at approxi-

mately 40 strokes per minute and ob-

chipped, that will not be indicated in any of the