Problem
Problem
Problem
Cause
Cause
Cause
Solution
Solution
Solution
Output low on down
stroke
Open or worn intake valve
Clear or service the intake valve.
Output low on up stroke
Open or worn piston valve
packings
Clear the piston valve. Replace the packings.
Fluid supply is exhausted
Refill the fluid supply and prime the pump.
Clogged suction
Clean the suction tube.
Open or worn piston valve
packings
Clear the piston valve. Replace the packings.
Open or worn intake valve
Clear or service the intake valve.
Clogged gun, hose, outlet,
etc.
Clear the gun, hose, outlet, etc.
Erratic or accelerated
pump speed
Open or worn outlet check
valve
Clear or service the outlet check valve.
Cycles or fails to hold
pressure at stall
Worn intake or piston valve or
seals
Service the pump lower (see your pump lower
manual).
Loose suction line
Tighten suction line connections. Use
compatible liquid thread sealant or PTFE tape
on connections.
Agitator/mixer is not
submerged
Submerge the agitator/mixer.
Air bubbles in fluid
Agitator/mixer RPM is too high
Lower the agitator/mixer RPM.
Incorrect fluid pressure at gun
See the gun manual. Read the fluid
manufacturer’s recommendations.
Fluid is too thin or too thick
Adjust the fluid viscosity. Read the fluid
manufacturer’s recommendations.
Poor finish or irregular
spray pattern
Dirty, worn, or damaged spray
gun
Service the spray gun (see spray gun manual).
Over voltage (greater than
300 V)
Check the power supply.
Driver does not turn
over and LED is off
No power to the control board
Contact your Graco distributor or Tech Service
for more information.
Driver does not turn
over and LED is on
Encoder fault
Cycle power.
Recalibrate the encoder following the procedure
listed in the King Driver Operation/Repair
manual.
Contact your Graco distributor or Tech Service
for more information.
Oil was over-filled
Drain and refill oil as stated in
Drain plug is not tightened
properly
Torque to 18–23 ft-lb (25–30 N•m).
Oil is leaking
Seal cartridge o-ring missing
or damaged
Replace the shaft bearing assembly.
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3A8126B