TESTING (cont) - TM-10-3930-638-24-P0856

TM 10-3930-638-24&P

4-3. FUEL SYSTEM MAINTENANCE (cont)

a. Fuel Injector (cont).

ITEM

REMARKS

ACTION

LOCATION

STEP

TESTING (cont)

a. Close pressure

Opening pressure check

gage valve

and flush

fuel injector

by operating

test pump

rapidly

NOTE

When testing more than one fuel injector out of engine, there

must not be more than 100 PSI difference between any

injectors in that engine

b. Open gage

Opening pressure for new fuel injectors

and raise

shall be 3150 to 3250 PSI; for used injec-

pressure

tors 2950 to 3050 PSI. Note and record

opening pressure

slowly

until

If injectors are not within 3150 to 3250

PSI (new injectors) or 2950 to 3050 PSI

injector

valve

(used injectors) opening pressure:

a. Adjust new fuel injectors (see adjust-

opens.

(Gage

ments)

reading

b. Valve lift screw may require adjust-

ment (see adjustments)

will drop

sharply

c. Disassemble and clean used fuel

at this

injectors (see disassembly)

point)

d. Check for broken or weak opening

pressure control spring (see inspec-

tion)

Seat leakage check

a. Point

injector

tip down

b. Operate

test pump

rapidly to

seat valve

firmly

c. Raise

A drop should not form on injector tip with-

pressure

in 10 seconds. Slight dampness is permis-

sible with a used injector. If drops form

at fuel

injector

on injector tip:

a. Disassemble and clean fuel injector

200 to 300

PSI under

(see disassembly)

recorded

opening pressure

4-78