High pressure test.

will decrease appreciably and a rise in pressure will

2. Open the tester fuel valve and operate

occur.

the pump handle to maintain test pressure.

(c) At this time the condition of the plunger

3. Check for leak at the injector rack

and bushing may be established. If there is ex-

opening. A leak indicates a poor bushing-to-body

cessive clearance between the plunger and bushing,

fit.

pressure beyond the normal valve opening pressure

4. A leak around the spray tip or seal ring

cannot be obtained. Replacement of the plunger

usually is caused by a loose injector nut, a damaged

and bushing assembly is then required.

seal ring, or a brinelled surface on the injector nut

or spray tip.

(d) P u m p u p t h e i n j e c t o r t e s t e r a n d

maintain a pressure of 1600 to 2000 psi by ac-

5. A leak at the filter cap indicates a

tuating the pump handle. Inspect for leaks at the

loose filter cap or a damaged filter cap gasket.

injector filter cap gaskets, body plugs, injector nut

6. A "dribble" at the spray tip orifices

seal ring area.

i n d i c a t e s a leaking valve assembly due to a

damaged surface or dirt. Leakage at the tip will

NOTE

cause preignition in the engine.

It is normal for some fuel leakage at the rack hole due

to high pressure fuel being applied to a normally low

NOTE

pressure area in the injector assembly.

A drop or two of fuel at the spray tip is only an in-

dication of fuel trapped in the spray tip at the

CAUTION

beginning of the test and is not detrimental as long as

Do not permit pressure in the injector

the pressure drop specified is not less than 40

tester to equal or exceed the capacity of

seconds.

the pressure gage.

(3) Spray pattern test.

(5) Visual inspection of plunger. An injector

(a) With injector mounted in the tester and

which passes all the previous tests should have the

the injector rack in Full Fuel position, operate the

plunger checked visually, under a magnifying glass,

pump handle to maintain a fuel pressure just below

for excessive wear or a possible chip on the bottom

the valve opening pressure.

helix. There is a small area on the bottom helix and

(b) Operate the injector several times with

lower portion of the upper helix, if chipped, that

the pump handle and observe the spray pattern

will not be indicated in any of the test. Remove the

emitted from the spray tip orifices. Fuel should be

plunger from the injector as follows:

discharged from each orifice and spray should

(a) S u p p o r t i n j e c t o r , right side up, in

produce a uniform pattern.

holding fixture.

(c) If spray does not produce a uniform

(b) Compress the follower spring. Using a

pattern, clean orifices in the spray tip (fig. 3-29).

screwdriver, raise the spring above the stop pin

(4) High pressure test.

and withdraw the pin (fig. 3-24). Allow the spring

(a) With the injector rack in the Full Fuel

to rise gradually.

position and the injector tester handle locked in

(c) Remove the injector from the holding

p o s i t i o n by means of handle lock (fig. 3-23),

fixture. Turn injector upside down, to prevent the

operate pump handle to build up and maintain the

entry of dirt, and catch spring and plunger as they

pressure.

fall out.

(b) Use the adjusting screw in the injector

(d) Inspect the plunger, and if chipped at

tester handle to depress the injector plunger just far

lower helix (fig. 3-21), replace the plunger and

enough to close both ports in the injector housing.

bushing assembly.

The point at which both ports are closed may be

easily ascertained by the fact that the injector spray

3-36