ARMY TM 9-2815-259-24 AIR FORCE TO 38G1-125-2 MARINE CORPS 09249A/09246A-24 3-46 2 If gauge needle reads different values on different attempts, does not move at all, or rapidly returns to “0”, fuel supply pump is defective and must be replaced. (c) Remove vacuum/pressure gage from fuel inlet (7) and install vacuum/pressure gage on fuel outlet (8). (d)     Move primer lever (6) all the way upward.  Release lever and at the same time observe gage.    1 Gauge needle should initially read 4-6 psi (28-41 kPa) , then quickly return to “0”.   This indicates that the outlet valve and diaphragm are in good condition, supply pump is operating properly and should be reinstalled on engine. 2 If gauge needle does initially read same value as indicated above and then returns immediately back to “0” fuel supply pump is defective and must be replaced. (e) Remove vacuum/pressure gauge from fuel outlet (8). (3)     Perform leakage test as follows: (a) Install a plug on fuel outlet (8, Figure 3-16). (b)     Install regulated pressure air line on fuel inlet (7, Figure 3-15) and apply 20 psi (140 kPa) pressure. __________ WARNING Diesel and JP fuels are flammable and toxic to eyes, skin, and respiratory tract.  Skin and eye protection required.  Avoid repeated/prolonged contact.  Provide adequate ventilation.  Failure to comply could result in serious injury or death. (c) Submerge pump in clean diesel fuel and look for air bubbles.  Replace fuel supply pump if air bubbles are present. (d)     Remove plug and regulated pressure air line. e.   Replacement. (1)     Remove fuel supply pump, refer to step b. (2)     Inspect fuel supply pump, refer to step c.  Replace fuel supply pump if lever face is worn flat or concave. (3)     Perform bench test, refer to step d.  Replace if fuel supply pump fails bench test. (4)     For installation of fuel supply pump, refer to step f.