Injector holding pressure test. O p e r a t e

TM 10-3930-242-34

Figure 3-19. Fuel injector control lever and tube assembly,

disassembly and reassembly.

m o u n t e d in test stand, pump and maintain a

tors by the fuel pump and serves as a coolant. In

pressure of 1600- to 2000-psi. Inspect for leaks.

a d d i t i o n to serving as a coolant, circulation of

R e l i e v e test pressure slowly to prevent damage

the surplus fuel bleeds away air or vapor in the

to test gage.

system back to the fuel tank where it is vented

t o the atmosphere. Surplus fuel leaving the in-

WARNING

jectors flows through outlet fuel line to fuel re-

The injector must always be held in such

t u r n passage and then through a restricted fit-

a way as to prevent any fuel from penet-

ting and a tube back to fuel supply tank.

rating a person's skin. Fuel oil which en-

b. Removal. Refer to figure 3-20 and remove,

ters the bloodstream could cause serious

fuel i n j e c t o r s and fuel lines.

infection or death.

NOTE

(2) Injector holding pressure test. O p e r a t e

Cap the filter caps with shipping cap after line

t h e tester to bring pressure up to approximately

removal to keep out foreign material.

450 psi. Close fuel shut off valve and note pres-

c. Fuel Injector Testing.

sure drop. Time for a pressure drop from 450 psi

(1) I n j e c t o r r a c k a n d p l u n g e r m o v e m e n t .

t o 250 psi should not be less than 40 seconds.

Check to see if plunger works freely in its bush-

Injector should be checked for leaks as follows:

i n g by placing injector against a bench and de-

(a) T h o r o u g h l y d r y i n j e c t o r w i t h c o m -

pressing follower to the bottom of its stroke

p r e s s e d air.

while moving the rack back and forth. Failure to

(b) Open tester fuel valve and operate

p r o d u c e a free rack indicates internal parts of

t e s t e r to maintain testing pressure.

injector are dirty or damaged. With injector