ADJUSTING OPENING PRESSURE
a. Test Stand Preparation.
(1) Open gage valve.
(2) Fill supply cup with diesel fuel.
(3) Operate pump handle to remove air from system; to ventilate system, open
vent screw located directly behind lower discharge fitting.
b. Connect fuel injector to upper discharge fitting using test stand adapters and
elbow. Be sure nozzle tip assembly is facing downward.
When testing more than one fuel injector, there shall not be more than
100 psi difference in opening pressure between injectors.
c. Check fuel injector opening pressure as follows:
Close gage valve.
Always direct injector tip away from you. Fuel from spray orifices can
penetrate clothing and skin causing serious infection. Always be sure
injector tip is enclosed in a receptacle (preferably transparent) to
contain spray. If skin is broken by fuel injector spray, immediately
wash injured part with boric acid solution.
Support injured member with
a splint and sling so it will remain absolutely at rest. Obtain medical
(2) Flush fuel injector by working test stand handle rapidly.
(3) Open gage valve and raise pressure slowly until fuel injector valve opens
(pressure gage reading will fall sharply at this point). Record opening
(4) If opening pressure is not 3400 to 3950 psi for used injectors or 3950 to
4100 psi for new injectors, go to step (5) below. If opening pressure is
within above range, go to step (9) below.
(5) Remove fuel injector from test stand and disassemble fuel injector (page
One shim kit contains enough pressure adjusting shims to adjust six
Using shim kit, add pressure adjusting shims to increase opening pressure
or remove pressure adjusting shims to decrease opening pressure.
(7) Reassemble fuel injector (page 4-84) .
(8) Repeat steps b and c(1) through (4) above.
(9) Test fuel injectors (page 3-110).