Step 8. Adjust the throttle to the desired pump speed. Increase the engine RPM by rotating the throttle
clockwise until approximately 3,850 RPM is indicated on the tachometer. When the pump is fully
primed, the sound of the pump will change noticeably.
NOTE: The governor on the engine is factory set to control the engine speed at 3,850 RPM. If the
engine will not operate at 3,850 RPM, notify organizational maintenance personnel.
Step 9. Both the pressure gage and the vacuum gage initially indicate zero. In operation, the pump
suction vacuum gage will read from 0 to 15 inches of mercury, depending on the height of the pump
above the water. When the pump is fully primed, the pressure gage indication should be 60 to 120 psi.
Step 10. Immediately close valve 4 when the pump is fully primed (Figure 29).
Figure 29. Close valve 4.
NOTE: Close valve 4 before the prime-detergent tank is empty. If this valve is not closed, all vacuum
pressure will be lost due to air in the pump.