SUMP PUMP TROUBLESHOOTING
 

Sump Pump Troubleshooting

 

Use caution when checking anything electrical.  Pumps use 115 volts AC which can injure or kill.

Always unplug the pump from power before servicing or inspecting it.

 

Symptom

Possible Cause

Corrective Actions To Check/Try

Pump won't start or run
Float switch is not being raised high enough
Check to see if float ball is stuck on something.  if so, remove obstacle.  If need be, reposition pump or remount switch in new position so it canot get stuck
Water level might not be high enough to engage switch.  Raise float manually or add water until float is at activation height to test switch. 
Pump is  not receiving enough electricity
Check outlet to ensure it has power.  If not, replace fuse or reset breaker in home's fuse/breaker box.
Plug pump directly into an outlet without using an extension cord.
If extension cord MUST be used, ensure tat it is of a heavy enough gauge wire to support the length of cord and horsepower of pump you're using.
Check that wire providing power to the outlet where pump is plugged in is adequate.
Pump should be plugged into an outlet that is fed by its own circuit breaker (or fuse). If circuit breaker feeds power to other outlets or appliances, have outlet installed that is fed by its own breaker.
Impeller is jammed with debris
Remove screen from bottom of pump and make sure nothing is preventing the impeller from moving freely.  Remove any obstrucions.
Float switch is defective
Bypass float switch.  Unplug pump's cord from the piggyback plug of float switch. Plug pump's plug directly into outlet to test. If pump runs, float switch is bad. Replace float switch.  (Do not leave pump plugged in too long or it will burn out)
Pump has shut down due to thermal overload
Pump may have run too long. Sump pumps are designed to empty sump pits only.  Use of a sump pump in a pond or waterfall will cause it to run too long and shut down.
Low voltage at the pump will also cause thermal overload and shut down.  Refer to item below labelled "Pump runs for a short time and ejects some water but shuts off before water is gone"
Pump is bad
If all items above check out OK, then pump is dead and needs to be replaced.
Motor hums but little or no water is ejected from pit
Motor is just humming -- not running
Follow diagnostics above for "Pump won't start or run"
Pump is air-locked
Drill 1/16" to 1/8" anti-airlock hole in pipe just above pump's discharge and just below check valve.
Check valve is stuck closed or installed incorrectly
Check valve usually has an arrow on it indicating water flow. Ensure it is pointing up toward discharge, not at pump.
Inspect to see if check valve is stuck closed.
Impeller is damaged
Inspect impeller for worn or missing blades. Replace impeller if needed.
Discharge pipe is partially or fully blocked
Check for blockages at discharge of pipe. If in cold area, see if pipe is frozen closed.
Discharge pipe has too many 90 degree elbows. 90's provide a lot of restriction. Using more than 3 or 4 can provide so much restruction that flow is reduced considerably.  Consider using 45's instead of 90's.
Suction intake screen is partly or fully blocked
Inspect suction screen at bottom for debris blocking it.  Remove debris.
Volute (bottom of pump) is cracked allowing water to leak out
Inspect bottom section of pump for cracks or holes that would allow water ot escape
Discharge pipe is leaking
Inspect discharge pipe and joints for any place where water can leave the pipe and go back into the sump pit.
Pump runs for a short time and ejects some water but shuts off before water is gone
Pump is overheated and shut off by thermal overload
Be sure plump is plugged directly into outlet.  If extension cord MUST be used, ensure it is heavy enough gauge for horsepower of pump and length of cord.  It is recommended that the outlet be fed by its own circuit breaker (or fuse).  If the breaker (or fuse) sends power to other things, the pump can be shorted of voltage when it starts.
Float switch is out of adjustment
Check if pump shuts off before float ball is all the way down.  If it's shutting down too early, adjust float switch per instructions in owners' manual.
Float switch is bad
If adjustment above did not resolve problem, or no adjustment is possible, replace float switch.
Pump runs continuously
Pump cord and float switch cord are plugged in separately.
Plug pump cord into piggyback connector on back/side of float switch plug.  Put the combination into a single receptacle of an outlet.
Float switch is stuck
Inspect pit for anything that can cause the float ball to get stuck and not settle to its 'off' position.  Remove obstacle or relocate pump or switch to avoid the obstacle.
Float switch is out of adjustment
For tethered stle float ensure there is mimum of 3" of cord between float ball and cord mounting bracket.
For vertical style floats, check adjustment of rubber stopper under the float ball at the bottom of the float rod.
Water is not being discharged from pit
See item above labeled "Motor hums but little or no water is ejected from pit"
Simply have too much water coming in
Check discharge to be sure water is being ejected from pit.  If it is, but water level in pit does not drop, then you simply have more water coming into the pit than the pump can move out. If pit is not overflowing, no real issue is present but you may wish to have a spare pump on hand in case the pump fails from over-use.
Using vertical style or electronic probe style float switch in sump pit that gets laundry water
Laundry water builds up soap scum on the float switch which will impede float movement. 
 
Soap scum on probes of electronic float switch can make contact even when water is gone “fooling” switch.
 
Only an effluent style pump with tethered style switch should be used if laundry water is to be pumped.
Pump starts and stops too often
Using a pump with vertical float where a pump with tethered float might be better
If your sump it is large enough in diameter and deep enough, using a pump with a tethered style float switch will allow the pump to be off longer between pump cycles.
Sump pit is very small
A very small sump pit will simply not hold as much water.  Enlarging the sump pit (if possible) would be wise
Float switch is out of adjustment
For tethered stle float ensure there is mimum of 3" of cord between float ball and cord mounting bracket.
For vertical style floats, check adjustment of rubber stopper under the float ball at the bottom of the float rod.
Water is coming back into pit from discharge pipe
After pump has run, inspect to see if water is coming back into pit through the sump pump.  If so, check valve has failed.  Replace check valve.
Simply have too much water coming in
Check discharge to be sure water is being ejected from pit.  If it is, but water level in pit does not drop, then you simply have more water coming into the pit than the pump can move out. If pit is not overflowing, no real issue is present but you may wish to have a spare pump on hand in case the pump fails from over-use.
Pump is noisy
Discharge pipe is rattling or banging against wall and/or floor joists
Put insulating foam between pipe and wall and/or joists. 
Can also try hanging the pipe with an exhaust hanger from an auto parts store.
Install a section of flexible rubber hose (like radiator hose) between the pump discharge and the discharge pipe to provide vibration insulation
Check valve slams shut causing a bang just after pump shuts off
Install a section of flexible rubber hose (like radiator hose) between the pump discharge and the discharge pipe to provide noise insulation
You may be using a pump that is higher in horsepower than you need.  It is causing the water to move too fast in the pipe.  After the pump shuts off the water column keeps moving upward for a moment, then slams down.
Pump is sucking air at end of its cycle
Adjust float switch per the owners' manual so it shuts off before it starts sucking air
Pump itself is vibrating
Inspect impeller for broken or missing blades.  Replace impeller or pump to rectify but also inspect sump pit to eliminate debris that could damage new item.
Fuse or circuit breaker feeding the outlet where pump is plugged in trips or blows when pump activates
Water got into cord and/or float switch connector (especially possible if your breaker is a GFCI type breaker)
Separate pump plug from switch plug use hair dryer to dry them out.
Remove cord connector from top of pump and dry out with cloth or hair dryer.
Impeller is stuck or jammed with debris
Remove screen from bottom of pump and make sure nothing is preventing the impeller from moving freely.  Remove any obstructions.
Using an extension cord or wiring to outlet is too light
Check to make sure the wire supplying power to the pump is appropriate for the horsepower and amp draw of the pum that's in place
Float switch is bad
Plug pump directly into outlet (without plugging into float's piggyback plug) to see if pump runs without popping breaker or fuse.  If it does, but it pops fuse/breaker when plugged in through float switch, the float switch is bad.  Replace float switch.
Pump motor has a shorted winding
Replace the pump

 

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