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TM 10-3930-638-24&P
4-3. FUEL SYSTEM MAINTENANCE (cont)
a. Fuel Injector (cont).
STEP
LOCATION
ITEM
ACTION
REMARKS
TESTING (cont)
3
Opening pressure check
a. Close pressure
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
slowly
opening pressure
until
If injectors are not within 3150 to 3250
injector
PSI (new injectors) or 2950 to 3050 PSI
valve
(used injectors) opening pressure:
opens.
a. Adjust new fuel injectors (see adjust-
(Gage
ments)
reading
b. Valve lift screw may require adjust-
will drop
ment (see adjustments)
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)
4
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-
at fuel
sible with a used injector. If drops form
injector
on injector tip:
200 to 300
a. Disassemble and clean fuel injector
PSI under
(see disassembly)
recorded
opening pressure
Seat leakage check
4-78
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