TM 9-4940-342-14&P Table 5-1.  Troubleshooting - Continued Malfunction Probable Causes Corrective Action 4.   Inadequate     water     supply,     low water pressure switch open (needs 15     psig     to     close)     (refer     to malfunction 1). - Continued m. Pump belt loose. m. Inspect   belt   for   tightness,   if   belt can  be  twisted  2/3  of  a  turn  tighten by  adjusting  motor  and  oil  pump  in slots in mounting base. 5.   Excess    temperature    switch    open (outlet temperature exceeds 370°F). a.  Improper thermostat setting (too high). a.  Observe    outlet    temperature    gage, Switch     opens     at     370°F.     Lower thermostat to desired operating temperature and manually reset switch. b.  Insufficient amount of water flowing through coil. b.  See malfunction 4. c.  Switch setting incorrect. c.  Observe   dial   set   point   adjustment. Switch  should  be  set  after  operating unit   at   high   fire   condition   for   ap- proximately    ½-hour.    Set    point    to trip burner at 370°F. d.  Switch not reset after high outlet temperature condition (may occur after coil blowdown). d.  Manually reset switch. 6.   Low oil pressure switch open, inadequate fuel supply pressure (closes at 45 psi at thermostat a.  Improper thermostat setting (too low or closed). a.  Observe  position  of  thermostat  and open (turn counterclockwise to open). outlet). b.  Fuel on-off supply closed (pump discharge valve). b.  Observe valve position and open. c.  Fuel pump suction strainer valve closed. c.  Zero   pressure   on   pump   discharge gage. Open the valve. d.  Fuel strainer dirty. d.  Zero    or    low    pressure    on    pump discharge gage. Shut strainer suction     valve.     Clean     or     replace strainer. e.  Oil pump rotation incorrect. e.  Observe   motor   rotation.   Should   be clockwise   when   viewed   from   front (pulley     end)     of     motor.     Correct rotation  by  reversing  any  two  of  the three 3-phase power leads. f.   Sensing connection for fuel pressure switch plugged. f.   Remove  ¼-inch  copper  tubing  from switch   and   connection   at   high   fire valve and turn on oil pump. Observe oil   flow   from   connection   at   valve. Inspect    for    foreign    material    and clean from the connection at high fire valve.     Blow     the     ¼-inch     tubing capillary out with air. g.  Fuel tank empty. g.  Oil    pressure    discharge    gage    will drop  in  pressure  trying  to  ignite  low fire burner. Refill tank. h.  Fuel pump recirculating by-pass adjusted improperly. h.  Oil    discharge    pressure    gage    in- dicates  low  or  high  pressure  (should be   set   110-120   psi).   With   pump running, remove protective cap from adjusting   screw.   Insert   screwdriver and     turn     clockwise     to     increase pressure    and    counterclockwise    to decrease pressure. i.   Fuel lines leaking, broken or plugged. i.   Inspect  piping  for  crimps,  breaks  or leaks     and     repair     or     replace     as necessary.    Disconnect    oil    supply piping  to  fuel  valves,  turn  on  pump, observe oil flow. Continue procedure on oil tubing connections from valve to  pump  until  the  plugged  section  is located,  and  blow  clear  with  air  or replace as necessary. 30