TM 5-3895-383-24 4. Plugged or damaged converter/muffler: Vehicles equipped with catalytic converter/ mufflers, especially  those  that  idle  for  long  periods  of  time and/or operate in cooler climates, are susceptible to plugging. One indication of a plugged converter/muffler   is   poor   engine   response.      For testing   procedures   of   converter/mufflers,   refer   to the  Testing  And  Adjusting  Section,  Measurement Of  Pressure  In  Exhaust  Manifold,  of  this  Service Manual. For information concerning the replacement   of   the   converter/muffler   refer   to   the Disassembly And Assembly Section, Converter/Muffler, of this Service Manual. 5. Fuel pressure is low: Make  sure  there  is  fuel  in  the  fuel  tank.    Look  for leaks or bad bends in the fuel line between fuel tank and  fuel  transfer  pump.    Look  for  air  in  the  fuel system.    Make  sure  the  fuel  filters  are  clean,  then check fuel pressure.  The outlet pressure of the fuel transfer pump must be a minimum of 200 kPa (29 psi) at full load speed.  If fuel pressure is lower than the  above  pressure,  check  the  fuel  transfer  pump and fuel pressure regulating orifice at the fuel return line. 6. Low quality fuel or water in fuel: Remove  the  fuel  from  the  fuel  tank.    Install  new  fuel filter.  Put a good grade of clean fuel in the fuel tank. Fuel   API   rating   can   be   easily   checked   using   the 1P7408 Thermo-Hydrometer.  Instructions are given in Special Instruction GMG00977-02. 7. Defect in fuel injector(s): Refer    to    Problem    No.    4,    Engine    Misfiring    Or Running Rough. 8. Valve adjustment not correct: Check  and  make   necessary   adjustments   as   per Testing    and    Adjusting    Section    of    the    Service Manual. 9. Incorrect fuel injection timing dimension: Check   and   make   necessary   adjustments   as   per Testing    and    Adjusting    Section    of    the    Service Manual. 10. Fuel setting incorrect: Check   and   make   necessary   adjustments   as   per Testing    and    Adjusting    Section    of    the    Service Manual.  See Fuel Setting And Related Information Fiche for the correct fuel setting. 11. Fuel injector control linkage binding: Disconnect the governor  output shaft from the fuel injector   control   linkage.      Check   the   linkage   for smooth  operation.    If  linkage  still  appears  to  be binding, remove injectors. With   injector   springs   compressed,   check   injector   racks   for smooth    operation.        Replace    injectors    with    "sticky"    racks. Check  linkage  again  for  smooth  operation.    If  still  binding, loosen  bolts  holding  linkage  to  cylinder  head.    Operate  the linkage by hand.  If binding is still present after retightening the bolts, replace the control linkage. 12. Problem with the governor: Bench test the governor.  If the governor cannot be properly  adjusted  during  bench  testing,  repair  or replace  the  governor.    Bench  test  the  repaired  or replacement governor. 13. Turbocharger  has  carbon  deposits  or  other  cause  of friction: Make     inspection     and     repair     turbocharger     as necessary. 14. Fuel Ratio Control (FRC): a. Check for defective or inoperative FRC. b. Check for restrictions. c. Check and make necessary adjustments to FRC. 15. Air, water, or gas in fuel: a. Check inlet line or transfer pump for air leak. b. Check sleeve or sleeve to head joint for water leak. c. Check injector seat erosion in sleeve or tip seal for combustion gas leak. Problem 9:  Engine Speed Is Not Stable Probable Cause(s): Fuel Pressure Is Low Engine Misfiring Fuel Injector Control Linkage Is Binding Improper Injector Synchronization Problem With Governor 6-38