TM 5-3895-383-24 b. With  the  engine  running  at  low  idle,  move  each injector    rack,    one    at    a    time,    gently    with    a screwdriver,   in   the   fuel-on   direction.      A   properly calibrated and synchronized injector will produce a knock  when  the  injector  is  moved  a  fraction  of  a millimeter in the fuel-on direction.  A knock will be present  when  an  injector  is  delivering  too  much fuel.      The   intensity   of   the   knock   will   increase immediately   when   the   rack   of   the   over-fueling injector is moved in the fuel-on direction.  When an injector is delivering too little fuel, a misfire with be evident.  Moving the rack of the offending injector in the  fuel-on  direction  a  fraction  of  a  millimeter  will eliminate the misfire.  The same results should be produced when each rack is moved individually the same  distance.    If  the  results  are  not  the  same, check rack synchronization and timing.  When rack synchronization   and   timing   are   correct   and   an injector fails the above test, replace the injector. c. With    the    engine    running    at    low    idle,    place   a screwdriver   blade   on   the   base   of   the   injector. Lightly   grasp   the   shaft   of   the   screwdriver   and evaluate   the   pulses   felt.      Each   injector   should produce the same pulse. If the rack synchronization    and    timing    is    correct,    and    an injector fails the above test, replace the injector. When  checking  rack  synchronization  make  sure  the  control linkage   rotates   freely   and   does   not   bind   or   stick.      During movement of the control linkage, the control linkage lever balls should   remain   engaged   in   the   rack   head   and   should   not contact the closed end of the rack head. 2. Broken Or Missing Injector Rocker Arm Insert Check  injector  rocker  arm  for  a  broken  or  missing injector rocker arm insert.  Replace as necessary. Problem 7:  Rough Idle Probable Cause(s): Fuel Injection Timing Not Correct Defect In Fuel Injector(s) 1. Fuel injection timing not correct: Check   and   make   necessary   adjustments   as   per Testing    and    Adjusting    Section    in    the    Service Manual. 2. Defect in fuel injector(s): Refer   to   Problem   6:      Knock   Or   Miss   At   Idle   to isolate the defective injector(s). When a miscalibrated    injector    is    suspected,    adjust    the synchronization  screw  in  and  out  to  smooth  that cylinder.  If the No. 1 injector is suspect, it should be  replaced  or  exchanged  with  another  injector  to confirm. Problem 8:  Low Power Probable Cause(s): Dirty Fuel Filters Oil Lever To High Restrictions And/Or Leaks In Air Inlet System Plugged Or Damaged Converter/Muffler Fuel Pressure Is Low Low Quantity Fuel Or Water n Fuel Defect In Fuel Injector(s) Valve Adjustment Not Correct Incorrect Fuel Injection Timing Dimension Fuel Setting Incorrect Fuel Injector Control Linkage Binding Problem With Governor Turbocharger Has Carbon Deposits Or Other Cause Of Friction Fuel Ratio Control (FRC) Air, Water, Or Gas In Fuel 1. Dirty fuel filters: Install new fuel filters. 2. Oil level too high: Remove dipstick and check oil level.  If level is too high,  drain  oil  to  bring  the  oil  level  to  the  desired level. NOTE: An oil sample should be run to find out if the oil level  is  increasing  due  to  a  fuel  leak  or  other engine problem. 3. Restrictions and leaks in the air inlet system. a. Check for leaks. b. Check the pressure in the air inlet manifold. c. Look for restrictions in the air cleaner. d. Defect    in    the    air    to    air    aftercooler.        Check temperature  of  inlet  and  outlet  air  from  air  cooler. Remove any external or internal restrictions. 6-37