TM 5-4940-228-14 d. Position  respirator  on  face,  fitting  wide  por- tion under chin, and narrow portion over nose, wear- ing as low as possible. Place upper band above ears to  top  of  head,  lower  band  below  ears  to  back  of neck, and adjust for tight seal. e. Test  for  proper  seal  by  removing  exhalation valve  guard,  remove  exhalation  valve  guard  close exhalation valve with your thumb and exhale gen- tly. If leakage is detected readjust head bands until tight seal of facepiece is obtained. f. Replace exhalation valve guard. 2-5. Starting. Start the unit as follows (Fig. 2-2): a. Screw  the  manual  unloading  knob  counter- clockwise (Fig. 2-6). NOTE The unloader pilot valve acts to pre- vent the air pulsation  chamber  from exceeding  80  psi  or  falling  below  65 psi  under  normal  operating  condi- tion.    When  the  manual  unloading knob  is  turned  counterclockwise  the unloader  pilot  valve  directs  air  to compressor unloaders which prevents the compressor from pumping air into the pulsation chamber. Thus, the com- pressor is unloaded and allows you to start the engine with less effort. b. Open valve on fuel filter. (Refer to TM 5-2805- 257-14 operating procedures). c. Set ignition switch to RUN. d. Place  throttle  control  approximately  1/4  inch (0.6 cm) forward of idle position. e.  Set   choke   on   carburetor   to   closed.   Less choking may be necessary due to variations in tem- perature,  grade  of  gasoline  or  altitude.  Generally, choking is not required when engine is warm. f. Wind  rope  around  pulley  and  give  a  quick steady  pull.  Keep  starter  rope  in  a  straight  line  with pulley.  If  a  second  pull  is  necessary,  move  choke back to middle position. g. Return choke to open position after engine has run  for  a  few  minutes,  move  throttle  to  full  gov- erned   position. h. Screw  the  manual  unloader  knob  clockwise. This will allow compressor to pump air into the pul- sation chamber (Fig. 2-6). CAUTION Operate the manual unloading knob with  your  fingers  only.  Do  not  use wrenches,  pliers,  or  other  tools  as they may damage or misadjust the un- loader pilot valve. i. Check pulsation chamber pressure gage, pres- sure  will  rise  slowly  until  a  reading  of  80  psi  is reached (Fig. 2-2). NOTE While spraying, the normal gage read- ing  will  vary  between  65  psi  and  80 psi. 2-6.  Emergency  Stopping. Move engine ignition switch to OFF. 2-7. Operation of Paint Spray Outfit. To operate the Paint Spray Outfit, proceed as fol- lows: a. Open  air  valves  on  pulsation  chamber.  This will allow air to fill red air hoses to pressure (paint) tank (Fig. 2-2). b. Close the slide valve by pushing towards fluid pressure  air  gage  (Fig.  2-3)  and  allow  pressure  to build  up  in  pressure  (paint)  tank  while  adjusting fluid pressure air regulator until fluid pressure air gage indicates 10 psi (Fig. 2-3). NOTE If you read higher than 10 psi on the fluid pressure air gage, open the slide valve  to  release  tank  pressure.  Un- screw handle on fluid pressure air reg- ulator two turns. Close the slide valve and  try  to  adjust  the  fluid  pressure air regulator again. c. Remove  air  nozzle  by  unscrewing  lock  ring (Fig. 2-4). d. Place waste material container beneath spray gun and test flow of fluid by pulling trigger all the way  back.  When  material  flows  steadily,  release trigger. e. NOTE This  step  is  necessary  to  fill  black fluid  hose  and  spray  gun  with  paint and remove trapped air. Replace air nozzle. 2-7