TM 10-3930-671-24 Injectors  that  fail  to  meet  the  acceptable  pressure  limits should be adjusted by adding or subtracting shims. Replace  any  injector  that  cannot  be  adjusted  to  meet pressure limit specifications. NOTE It  is  always  a  good  practice  to  have all the injectors of any one engine set as   nearly   alike   as   possible.      This makes for a smoother running engine. STEP 3:  Once the pressure setting has been confirmed, check the nozzle spray pattern.  Hold constant pressure on  the  tester  lever  to  maintain  the  opening  pressure  of the   nozzle.      Watch   for   dribble   from   the   spray   orifice which indicates a bad seal.  Also, look for leaks along the body  of  the  nozzle  holder  itself  which  indicates  a  leak between the holder and the valve body lapped surfaces. STEP 4:  Now work the pump handle rapidly (about 100 strokes    per    minute)    and    observe    the    spray    pattern produced.· Check that spray pattern is a 'straight shot" or that isn’t aimed off to one side.  The spray pattern should exit  the  injector  in  the  form  of  a  thin  line  stream  that gradually gets a little wider before developing into a small mist cloud out at the end. FUEL INJECTION PUMP The   function   of   a   diesel   fuel   injection   pump   is   to accurately  meter  and  deliver  fuel  to  a  nozzle  in  each cylinder   and   to   inject   it   at   high   pressure   into   the combustion  chamber  at  precisely  timed  intervals.    The extreme  precision  necessary  can  well  be  appreciated since this cycle must be repeated thousands of times per minute  with  virtually  no  variation  in  timing  or  amount  of fuel injected. Removal of the Fuel Injection Pump Remove all high-pressure fuel lines being careful not to bend   them.      Disconnect   any   low-pressure   fuel   lines, linkage rods, or electrical wires that need to come off to allow injection pump removal from the engine.  Remove the three long bolts that go completely through the timing gear  cover  and  remove  the  injection  pump.    DO  NOT separate  the  injection  pump  from  the  adaptor  mounting plate  unless  absolutely  necessary.    This  will  save  you much time during reinstallation of the pump if the pump is going back onto the same engine. STANADYNE MODEL DB2 INJECTION PUMP The   model   DB2   injection   pump   is   described   as   an opposed-plunger,   inlet-metered,   positive-displacement, distributor-type  pump.    The  DB2  pump  incorporates  a single  pumping  chamber.    Precise  distribution  between cylinders, inherent in the pump design, and the ability to preset  fuel  flow  eliminates  lengthy  periods  on  the  test stand.      The   pump   is   self-lubricated,   and   contains essentially  the  same  number  of  parts  regardless  of  the number of cylinders served. Working Principle The   main   rotating   components   are   the   drive   shaft, transfer pump blades, distributor rotor, and governor. The  drive  shaft  engages  the  distributor  in  the  hydraulic head.  The drive end of the DB2 rotor incorporates two pumping plungers. The plungers are actuated toward each other simultaneously  by  an  internal  cam  ring  through  rollers and shoes which are carried in slots at the drive end of the rotor.  The number of cam lobes normally equals the number of engine cylinders. F-154