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2. The pump runs but at
reduced performance or
does not deliver water.
a) Wrong direction of rotation. Check wiring for proper connections. Correct
wiring.
b) Pump is not primed or is air-bound. Turn pump off, close isolation valve(s) and
remove priming plug. Check liquid level. Refill
the pump, replace plug and start the pump. Long
inlet lines must be filled before starting the
pump.
c) Strainers, check or foot valves are clogged. Remove strainer, screen or check valve and
inspect. Clean and replace. Reprime pump.
d) Suction lift too large. Install compound pressure gauge at the inlet
side of the pump. Start pump and compare
reading to performance data. Reduce suction lift
by lowering pump, increase inlet line size or
removing high friction loss devices.
e) Inlet and/or outlet pipes leaking. (Pump spins
backwards when turned off)
Air in inlet pipe. Inlet pipe, valves and fittings
must be airtight. Repair any leaks and retighten
all loose fittings.
f) Pump worn. Install pressure gauge, start pump, gradually
close the outlet valve and read pressure at
shutoff. Convert measured pressure (in psi) to
head (in feet): (Measured psi x 2.31 ft/psi = ___
ft). Refer to the specific pump curve for shutoff
head for that pump model. If head is close to
curve, pump is probably OK. If not, remove
pump and inspect.
g) Pump impeller or guide vane is clogged. Disassemble and inspect pump passageways.
Remove any foreign materials found.
h) Incorrect drain plug installed. If the proper drain plug is replaced with a
standard plug, water will recirculate internally.
Replace with proper plug.
i) Improper coupling setting. Check/reset the coupling. See page 18.
3. Pump cycles too much a) Pressure switch is not properly adjusted or is
defective.
Check that pressure switch is set and functions
correctly. Check voltage across closed contacts.
Readjust switch or replace if defective.
b) Level control is not properly adjusted or is
defective.
Check that level control is set and functions
correctly. Readjust setting (refer to level control
manufacturer’s data). Replace if defective.
c) Insufficient air charging or leaking tank or piping. Pump air into tank or diaphragm chamber.
Check diaphragm for leaks. Check tank and
piping for leaks with soap and water solution.
Check air-to-water volume. Repair as
necessary.
d) Tank is too small. Check tank size and air volume in tank. Tank
volume should be approximately 10 gallons for
each gpm of pump performance. The normal air
volume is 2/3 of the total tank volume at the
pump cut-in pressure. Replace tank with one of
correct size.
e) Pump is oversized. Install pressure gauges on or near pump inlet
and outlet ports. Start and run pump under
normal conditions, record gauge readings.
Convert psi to feet (Measured psi x 2.31 ft/psi =
____ ft) Refer to the specific pump curve for that
model, ensure that total head is sufficient to limit
pump delivery within its design flow range.
Throttle pump outlet flow if necessary.
Problem Possible cause Remedy
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