Use  clean  diesel  fuel  for  washing  the  parts. Disassemble one nozzle at a time to prevent mixing of mating  parts.  Exercise  care  to  prevent  damage  to  nozzle parts.  Inspect  and  clean  all  parts  as  they  are disassembled. Carbon may be scraped from the outside of the nozzle, but be careful not to mar the edges of the holes (orifices). When cleaning fluid is used to clean the nozzle parts, dip the parts in diesel fuel immediately after cleaning. This will prevent moisture from the hands from marring the highly polished surfaces. Reaming tools and special drills are provided for cleaning spray nozzle holes. No drills other than those recommended  by  the  manufacturer  should  be  used.  The drills are hand-operated, using a cleaning needle that is held in place by a small chuck, called a pin vise (fig. 5-45). In performing reaming operations, remove only the foreign matter; be particularly careful not to burr the metal. WARNING Diesel fuel is a hazardous material. Avoid prolonged skin contact and wear goggles. Keep fire and flame away. Dispose of waste material and cleaning rags as hazardous waste. For  more  information,  see  OPNAVINST 4110.2,  Hazardous  Material  Control  and Management. Q31. When should water be drained from the fuel system? Q32.  What  is  the  first  requirement  when disassembling an injector for cleaning? GENERAL  TROUBLESHOOTING LEARNING OBJECTIVE: Describe general troubleshooting  techniques  used  in  the maintenance of a diesel fuel system. Figure 5-45.—Cleaning injector spray nozzle holes. When troubleshooting a diesel engine, keep in mind that problems associated with one make and type of engine (two-stroke versus four-stroke) may not occur exactly in the same way as in another. Specifically, particular features of one four-stroke-cycle engine may  not  appear  on  another  due  the  type  of  fuel system used and optional features on that engine. Follow  the  basic  troubleshooting  steps  listed  below before rolling up your sleeves and trying to pinpoint a problem area. 1. 2. 3. 4. 5. 6. 7. 8. 9. Obtain as much information from the operator as possible concerning the complaint. Analyze the problem in detail first, beginning with the smallest and simplest things. Relate the problem symptoms to the basic engine systems and components. Consider any recent maintenance or repair job that  might  tie  into  the  problem. Always  double-check  and  think  about  the problem before disassembling anything. Solve the problem by checking the easiest and simplest  things  first. If possible, use the special tools and diagnostic equipment at your disposal to verify acomplaint and  pinpoint  the  general  area. Determine the cause(s) of the problem and carry out the repair. Operate the engine and road test the vehicle to confirm that the problem is corrected. EXHAUST SMOKE COLOR One   of   the   easiest   methods   to   use   when troubleshooting  an  engine  for  a  performance  complaint is to monitor the color of the smoke coming from the exhaust stack visually. There are four basic colors that may exit from the exhaust system at any time during engine operation—white, black, gray, or blue. The color of the smoke tips you off to just what and where the problem might lie. White  smoke  is  generally  most  noticeable  at engine   start-up,   particularly   during   cold conditions. As the combustion and cylinder temperatures  increase  during  the  first  few minutes of engine operation the white smoke should  start  to  disappear  which  indicates  the engine is sound. However, if the white smoke 5-52