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9. Troubleshooting Chart
Flow Rate Lower
than Expected
Motor Speed too low
Check voltages, frequency, wiring, and terminal
connections. Check nameplates vs.
Check Valves worn or dirty
Clean, replace if damaged
Hydraulic bypass valve operating
each stroke
Refer to Hydraulic Bypass Valve
Product Viscosity too high
Lower viscosity. Increase pump and/or piping
size
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
Clean, replace if damaged
Correct for bypass valve leakage
Piston seal worn or damaged by
contamination
Inspect and replace if necessary, refer to
Piston seal
Pump does not
start
Blown fuse, and circuit breaker
Replace – eliminate overload
Check wiring diagram and correct
No Delivery
Check power source. Check wiring diagram
Ball check valves held open with
solids
Increase suction pressure
Re-prime, and check for leak
Remove and clean, replace screen if necessary
Hydraulic system under-primed
Delivery Erratic
Increase suction pressure
Entrapped air or gas in product
Ensure proper venting of system
Check voltage and frequency
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
Back pressure valve leaks
Repair, clean, or replace
Pump loses