TM 5-3895-374-24-2 6.  White Smoke Formation on Oil Firing A. Oil/Air ratios incorrect due to excess air, or oil flow is too low.  Readjust for proper fuel input, CO2 and smoke reading. 7.  Gray or Black Smoke Formation on Oil Firing A. Impingement on cold combustion chamber surfaces due to   undersized   chamber,   or   incorrect   oil   nozzle   spray angle  for  application.    This  could  also  result  in  carbon formation   on   chamber   surfaces.      Refer   to   chamber sizing,   page   12,   Fig.   16   and   page   13,   Table   7   for additional  information.    If  chamber  is  the  correct  size, change nozzle spray angle in order to shorten or narrow the flame as required. B. Defective or dirty oil nozzle.  Replace or clean nozzle. C. Incorrect  oil/air  ratios.    Readjust  burner  to  correct  CO2 and smoke levels. D. Oil    pressure    too    low    resulting    in    poor    atomization. Readjust. E. Impingement of raw oil spray on the blast tube choke ring or oil nozzle air diffuser.  Make certain that the diffuser is seated   firmly   against   the   oil   nozzle   adapter   shoulder, except on C5-OB, C5-GO-30B or other special applications  indicated  on  burner  data  shipped  with  the unit.    See  page  32,  Figs.    30,  31  and  32  for  additional information.  Position the oil gun assembly  fore  or  aft  in the blast tube to assist in elimination of  oil  spray  on  the blast tube choke ring. 8.  Oil High Fire Input Rate Cannot Be Achieved A. Oil  nozzle  size  too  small.    Remove  nozzle  and  check markings.  Replace with correct size nozzle. B. Nozzle  defective-replace.    Nozzle  mesh  filter  dirty-clean or replace. C. Oil supply pressure to nozzle too low.  Readjust. D. Oil pump defective.  Replace. E. On  Low/High/Off  and  Low/High/Low  systems  N.C.    oil solenoid   valve   in   nozzle   return   line   not   closing   (or leaking).          Check     valve     operation     and     replace     if necessary. F. On  two-step  pump  -  N.O.    pump  mounted  oil  solenoid valve defective (not closing).  Replace valve or pump. G. Oil pump coupling loose (slipping) or defective. Replace. H. Linkage mechanically binding.  Readjust. I. On   modulating   burner,   oil   nozzle   return   line   metering valve  set  incorrectly.    Readjust  to  attain  required  nozzle bypass pressure. J. Oil   suction   line   too   small   or   partially   blocked.      Make vacuum test while at high fire.  If the vacuum is in excess of  10”  HG,  consult  line  sizing  chart  on  page  10.    Make line size changes, if required. K. Blocked or dirty suction line oil filter.  Replace or clean. L. Manual valves in suction line not fully open.  Check and correct. M. Suction    line    check    valve    or    foot    valve    operating incorrectly.  Check and correct. N. Vent  system  on  oil  tank  blocked  creating  vacuum  on tank,  with  high  vacuum  and  lowered  oil  flow  to  burner. Check and correct. Additional trouble shooting information can be found in the Flame Safeguard Control bulletin supplied with the burner. (page 3 - 991)