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9.
Troubleshooting Chart
ISSUE
POSSIBLE CAUSES
REMEDY
Flow Rate Lower
than Expected
Motor Speed too low
Check voltages, frequency, wiring, and terminal
connections. Check nameplates vs.
specifications.
Check Valves worn or dirty
Clean, replace if damaged
Hydraulic bypass valve operating
each stroke
Refer to
Hydraulic Bypass Valve
Calibration system error
Evaluate and correct
Product Viscosity too high
Lower viscosity. Increase pump and/or piping
size
Product cavitation
Increase suction pressure
Piston seal worn or damaged by
contamination
Inspect and replace if necessary, refer to
Piston Seal (Section 8 Maintenance)
Process pressure relief valve leaking
or relieving
Repair, adjust or replace
Delivery
gradually drops
Check Valve Leakage
Clean, replace if damaged
Leak in Suction Line
Locate and correct
Strainer Fouled
Clean or replace screen
Product change
Check viscosity
Bypass leakage
Correct for bypass valve leakage
Piston seal worn or damaged by
contamination
Inspect and replace if necessary, refer to
Piston seal
Supply tank vent plugged
Unplug vent
Pump does not
start
Coupling Disconnected
Connect Coupling
Faulty power source
Check power source
Blown fuse, and circuit breaker
Replace – eliminate overload
Broken Wire
Locate and repair
Wired Improperly
Check wiring diagram and correct
Pipeline blockage
Open valves
No Delivery
Motor not running
Check power source. Check wiring diagram
Supply tank empty
Fill tank
Lines clogged
Clean and flush
Closed line valves
Open valves
Ball check valves held open with
solids
Clean and inspect
Vapor lock, cavitation
Increase suction pressure
Prime lost
Re-prime, and check for leak
Strainer clogged
Remove and clean, replace screen if necessary
Hydraulic system under-primed
Re-prime the pump
Delivery Erratic
Leak in suction line
Locate and correct
Product cavitation
Increase suction pressure
Entrapped air or gas in product
Ensure proper venting of system
Motor speed erratic
Check voltage and frequency
Fouled check valves
Clean, replace if necessary
Delivery higher
than rated
Suction pressure higher than
discharge pressure
Install backpressure valve or consult factory for
piping recommendations
Back pressure valve set too low
Increase setting
Back pressure valve leaks
Repair, clean, or replace
Calibration error
Review calculations
Pump loses
hydraulic oil
Diaphragm ruptured
Replace diaphragm
Leaky seal
Replace seal
Cover gasket leaks
Replace or retighten
