TM10-3930-660-34 4-3. FUEL INJECTOR - TEST/REPLACE (Cont’d) a.  Connect injector to fuel injector  test set. b.  Open valve and operate pump lever at a rate of one stroke per second while observing test pressure gauge. c.  Spray must begin at a pressure of 3553+73 psi. d.  If spray does not begin within pressure range specified in STEP c,  change thickness of shims (20).  Adding shims will increase opening pressure.  Remove shims to decrease opening pressure. e.  Check for well atomized spray pattern. 2.  LEAKAGE TEST. a.  Use same test setup as for opening pressure test (STEP 1,  above). b.  Open valve on test set. c.  Operate pump lever as necessary to hold pressure at a level about 290 psi below opening pressure noted in STEP 1c,  above. d.  No drops must fall from nozzle tip for a period of 10 seconds,  while maintaining pressure specified in STEP 2c,  above. If drops do appear within 10 seconds, replace injector. 3.  CHATTER TEST. a.  Use same test setup as for opening pressure test (STEP 1,  above). NOTE Do not evaluate used nozzles at lower pumping rates.  A used nozzle is serviceable if it passes the leakage test,  chatters audibly at higher pumping rates and uniformly atomizes fuel. 4-7