for a fault in other parts of the engine; damage to the engine  will  result. When  you  check  the  fuel  pump  on  the  engine, remove the pipe plug from the pump shutoff valve and connect  the  pressure  gauge.  At  the  governed  speed  (just before  the  governor  cuts  in),  maximum  manifold pressure  should  be  obtained.  If  the  manifold  pressure  is NOT  within  specified  limits,  adjust  for  maximum manifold pressure by adding or removing shims from under the nylon fuel adjusting plunger in the bypass valve plunger. Be careful you do not lose the small lock washer  that  fits  between  the  fuel  adjusting  plunger  and the plunger cap. To check the suction side of the pump, connect the suction gauge to the inlet side of the gear pump. The valve in the pump, if properly adjusted, should read 8 inches on the gauge. When the inlet restrictions reaches 8.5 to 9 inches, change the fuel filter element and remove any other sources of restriction. The engine will lose power when the restriction is greater than 10 to 11 inches. Always make the above checks on a warm engine. Also, operate the engine for a minimum of 5 minutes between checks to clear the system of air. If the pump manifold and suction pressures are within specified limits and there is still a loss of power, you should check the injectors. Carbon in the PT injector metering orifices restricts the fuel flow to the injector cups, which results in engine power  loss.  Remove  the  carbon  from  the  metering orifices  by  reverse  flushing;  it  should  be  performed  on a   warm   engine.   To   remove   carbon,   perform   the following  steps: 1. Loosen all injector adjusting screws one turn from the bottom or one and one-eighth turns from the set position. Lock with the jam nut after completing the required turns. 2. Start the engine and accelerate with maximum throttle from idling to high-10 to 15 times. 3. Readjust the injectors to their standard setting. The  engine  will  be  difficult  to  start  with  the  loose injector setting; it will smoke badly and will be sluggish. If the injector adjusting screws are loosened, the meter orifice will not be closed during injection. Extremely high injection pressure will force some of the fuel to backflow through the orifice and should remove carbon deposits. If this method is not effective, remove the injectors for cleaning. When  working  on  the  PT  fuel  system  of  a turbocharged Cummins engine, you may find an aneroid control device. This device creates a lag in the fuel system so that its response is equivalent to that of the turbocharger,  thus  controlling  the  engine  exhaust emissions  (smoke  level). WARNING The aneroid is an emissions control device. Removing it or tampering with it is in direct violation of state and federal vehicle exhaust emissions  laws. During  troubleshooting  of  the  fuel  system,  you should   check   the   aneroid   according   to   the manufacturer’s  specifications. Pump  Disassembly If you determine that the fuel pump (fig. 5-34) must be   removed   from   the   engine,   take   the   following precautions: . Make sure the shop area is clean. l Use clean tools. Good  cleaning  practices  are  essential  to  good quality fuel pump repair. Take special care when the PT fuel pump, which is made of a lightweight aluminum alloy,  is  disassembled.  Use  proper  tools  to  prevent damage to machined aluminum surfaces, which are more easily damaged than parts made of cast iron. Before disassembling the unit, try to determine what parts  need  replacement. After you place the fuel pump on the holding device, place the device in a vise and disassemble the pump. Follow  the  procedures  given  in  the  manufacturer’s maintenance and repair manuals. Pump Cleaning and Inspection Now that the pump has been disassembled, you should clean and inspect all parts. Do not discard parts until they are worn beyond reasonable replacement limits. The PT fuel pump parts will continue to function long after they show some wear. Parts that are worn beyond  reasonable  replacement  limits  must  not  be reused.   From   experience   you   know   reasonable replacement limits. Reuse all those parts that will give another complete period of service without danger of failure. 5-27