TM 10-3930-653-14&P 4-5-3-1.  DESCRIPTION The  fuel  pump  transfers  fuel  from  the  tank  to  the carburetor    in    sufficient    quantity    to    meet    the    engine requirements at any speed or load. The fuel pump is a pulsating type designed for easy maintenance.        It    consists    of    a    body,    rocker    arm assembly,  fuel  diaphragm,  fuel  diaphragm  spring,  seal, inlet and outlet valves. The   fuel   diaphragm   consists   of   specially   treated rubber,  which  is  not  affected  by  gasoline  and  held  in place by two metal discs and a pull rod. 4-5-3-2.  REMOVAL AND DISASSEMBLY WARNING Fuel   and   oil   are   slippery   and   can cause  falls.  To  avoid  injury,  wipe  up spilled fuel or oil with rags. Remove   fuel   pump   assembly   by   unscrewing   two mounting nuts and disassemble in the following order. (1)  Separate upper body and lower body by unscrewing body set screws. (2) Take off cap and cap gasket by removing cap screws. (3)  Unscrew  elbow and connector. (4)  Take off valve retainer by unscrewing the two valve retainer screws and the two valves are easily removed. To  remove  diaphragm.    press  down  on  its  center against the spring force.  With diaphragm pressed down. tilt it until the end of the pull rod touches the inner wall of body.  Then, release diaphragm to unhook the push rod. Use care during this operation not to damage diaphragm or oil seal. Drive  out  rocker  arm  pin  by  using  a  press  or  hammer. 4-5-3-3.  INSPECTION (1)  Check upper body and lower body for cracks. (2)    Check  valve  assembly  for  wear  on  valve  and  valve spring.  Blow into valve assembly with breath to examine its function. (3)    Check  diaphragm  for  small  holes,  cracks  or  wear. and replace as necessary. (4)    Check  rocker  arm  for  wear  at  mating  portion  with camshaft. (5)  Check rocker arm pin for wear. Worn pin may cause oil leakage. (6)    Check  all  other  components  for  any  abnormalities and replace if necessary. 4-5-3-4.  ASSEMBLY Reverse the order of disassembly.   Closely  observe the following instructions. (1)  Use new gaskets. (2)  Lubricate rocker arm, rocker arm link and rocker arm pin before installation. (3)  To test the function, proceed as follows: Position  fuel  pump  assembly  about  1  meter  (3.3  ft) above fuel level of fuel strainer and connect a pipe from strainer to fuel pump. Operate  rocker  arm  by  hand.    If  fuel  is  drawn  up soon    after    rocker    arm    is    released,    fuel    pump    is functioning properly. 4-66