34
PI-121
January 2020
Problem
Remedy
Constant Pressure
Mode or Shut-
In Mode: Some
water flows to gun
when gun triggers
are squeezed, but
the total system
pressure drops
drastically.
1. Check all hoses, connections, and control gun for
high-pressure water leaks.
2. Check gun nozzles for leaks and worn or blown
orifices. If operating in Constant Pressure Mode,
be sure they are sized correctly to match the flow
of the fixed orifice in the Multi-Mode Valve dump
port. If operating in Shut-In Mode, check that the
nozzles selected to not exceed flow capabilities.
3. Check that water is not leaking through Multi-
Mode Valve dump port. If it is leaking:
• Verify that at least 80 psi air pressure is read
on Multi-Mode Valve gauge while triggers are
squeezed. Increase if necessary, but do not
exceed maximum air pressure of the gun’s air
motor.
• Remove and check cartridge from Multi-Mode
Valve for seal wear and debris or wear of valve
and seat metal-to-metal sealing surfaces.
Replace if necessary.
• If neither of the actions above correct the prob-
lem, remove the four capscrews that connect
the air cylinder to the mounting plate on top
of the valve body, but do not remove the cap-
screws that hold the air cylinder together, and
do not disconnect the air line that connects the
cylinder to the brass pilot valve.
• Check for evidence of rubbing by the piston
of the air cylinder against the bore inside the
plate that is mounted above the Multi-Mode
Valve body. If any is visible, center the cylinder
over the plate, reattach, and re-check system
operation.
• If the piston on the underside of the cylinder
does not extend outward and retract when
the gun triggers are squeezed and released,
replace air cylinder.