TM 9-4940-342-14&P Table 5-1.  Troubleshooting - Continued Malfunction Probable Causes Corrective Action 6.   Low  oil  pressure  switch  open, inadequate fuel supply pressure (closes at 45 psi at thermostat j.   Oil    pressure    switch    bellows    rup- tured. j.   Oil   emitting   from   pressure   switch bellow,   assembly,   replace   pressure switch. outlet) - Continued k.  Fuel pump worn. k.  Remove     pump,     disassemble     and inspect seals, impeller, housing, bearing,   etc.   for   wear   or   breakage. Replace  defective  parts  or  pump  as necessary 7.   Excess pressure switch open (at 350 psi outlet pressure). a.  One discharge valve closed when on two gun operation. a.  Observe     valve     positions,     assure both discharge valves are open. b.  Both    discharge    valves    closed    or throttled. b.  Observe     valve     positions,     assure both discharge valves fully open. c.  Improper thermostat setting, causing excessive pressure- temperature rise in coil. c.  Observe     temperature     and     outlet pressure   gages.   Refer   to   operating instructions   for   correct   temperature setting for desired operational mode. d.  Check    valve    in    switch    stuck    in closed position locking high pressure in bellows assembly. d.  Remove    sensing    connection    from switch.  Remove  switch  and  inspect check valve in bellows inlet assembly for  freedom  of  movement  or  foreign material.  Start   pump   and   flush   the sensing    connections.    Clean    check valve,     assuring     it     moves     freely. Replace switch as necessary. e.  Improper nozzle size on gun or guns for operation mode. e.  Inspect    nozzles    in    use,    Refer    to operating instructions for nozzle size used on desired operational mode. f.   Excessive  scale  buildup  in  nozzles, restriction in guns or hoses. f.   Remove, inspect and descale nozzles and guns. Pump water thru hose and observe if flow is free. Blow air thru hose or replace hose as necessary. 8.   Flame  failure  "Red  Indicator  Light On". (Flame signal voltage below 2V DC). a.  Dirty scanner ultraviolet bulb. a.  Remove   scanner,   inspect   bulb   and clean   with   a   soft   cloth   with   non- caustic detergent. b.  Burner nozzle loose or off adapter. b.  Remove  burner  and  inspect  nozzles. Tighten or replace nozzles as necessary. c.  Burner   nozzle   connected   to   wrong fuel   valve   (low   fire   and   high   fire valves). c.  Remove  burner  and  inspect  nozzles, correcting nozzles and fuel tubing as necessary.   Assure   fuel   tubing   from fuel   valve   is   connected   to   proper burner. 10 GPH nozzle should be on low  fire  burner  (farthest  away  from scanner   sight   tube).   5   GPH   nozzle should be on high fire burner (closest to sight tube). d.  Electrodes out of alignment. d.  Remove     burner     and     check     that electrodes   are   adjusted   to   1/16   to 3/32-inch. Adjust electrodes to proper    dimensions    or    replace    as necessary. e.  Electrodes out of alignment. e.  See malfunction 2, step m. f.   Electrodes cracked. f.   See malfunction 2, step n. g.  Burner    nozzles    dirty,    plugged    or worn. g.  Remove  burner  and  inspect  nozzles. Clean, repair or replace as necessary. h.  Defective scanners. h.  Scanner  does  not  detect  flame  (zero voltage     at     flame     safeguard     test jacks). Replace scanner. i.   Oil or paint in scanner sight tube. i.   Remove    burner    and    inspect    sight tube,  clean  off  all  oil  and  paint  with alcohol. 31