5
Pumping Technology
FAULT FINDING
Fault
Cause
Action
Motor does not start
Electrical supply isolated
Check motor terminals for correct voltage
Blown Fuses
Replace fuses and check current
Loose electrical connections
Tighten all electrical connections
Motor runs and then cuts out
Undersized wiring
Rewire with larger cable
Starter overload tripped
Check overload sizing with motor F.L.C
Incorrect motor links
Check motor links for star/delta
Pump failing to deliver
Not primed
Bleed pump of air
Suction valve not fully open
Open Valve
Foot valve not fully submerged (open circuits) Lower suction pipework
Air leaks in suction pipework
Recheck all joints
Wrong Rotation
Change Rotation (check wiring phases)
Foreign body in pump case
Clear obstruction
Pump leaking
Mechanical seal damaged
Replace seal
Casing “O” Ring damaged
Replace “O” ring
Pump unduly noisy
Pipework not supported correctly
Check pipe supports
Pipework causing undue strain on pump
casing
Resupport pipework or reinstall pipework
Cavitation (closed systems)
Increase static head
Cavitation (open systems)
Increase size of suction pipework
Insufficient flow
Incorrect rotation
Change rotation (check wiring phases)
Low voltage
Check Electrical supply
Air leaks in suction pipework
Recheck all joints
Valves not fully open
Open all valves
Partially clogged pump or pipework
Clear obstructions
Pump too small
Replace pump
Motor does not start but emits a
‘hum’
Foreign body in pump casing
Check motor is free to turn
1 phase motors, faulty capacitor
Pump will operate correctly if ‘spun’ but if it
fails to re-start, replace capacitor
3 phase motors, phase dropped
Check the supply phase
