Sump Pump Troubleshooting

October 31, 2015
Sump Pump Diagram

Why won’t my sump pump start?

Float Switch
Inspect the float switch ball to ensure it moves up and down freely and is not stuck. Remove any obstacles or calcifications from the joint or ball. The pump should only run when the water level lifts the float switch on, via the float switch ball. Raise the ball manually. The pump should start. If not, bypass the float switch and plug the piggyback plug of the pump directly into an outlet. If pump starts, the float switch is defective. If not…

Electrical Issue
Ensure the pump is plugged in, check the fuse and reset your circuit breaker. If you’re using an extension cord, make sure it is heavy-duty enough to support the necessary horsepower demands of your pump. Test the pump’s wall outlet for electric current. Most sump pumps will have their own circuit. If you do not, you may need to have one installed. Or…

Impeller Blockage
Remove bottom screen of pump and clean impeller blockages.

Pumps can overheat and shut-off due to overuse or low voltage. Give your pump time to cool down.

If you’ve run through the list above, and cannot find the issue, your pump is bad and needs to be replaced.

Why does my Sump Pump turn on but not move water?

Motor is humming but not pumping
See above list.

Check Valve
The check valve is marked by an arrow, indicating the flow of water. Ensure it is pointing away from the pump, towards the discharge pipe. Make sure the valve is not stuck.

Impeller Blades & Suction Screen
Replace any worn or missing impeller blades. Clean debris from suction screen.

Line Blockage
Check discharge pipe for blockages or pipe freezing. Clear line.

Inspect pump body and discharge pipes for leaks that would allow suctioned water to escape.

Drill a 1/16″ to 1/8″ anti-airlock hole in the pipe a centimeter above the pump discharge and a centimeter below the check valve.

Why does my sump pump keep shutting off?

Pumps can overheat and shut-off due to overuse or low voltage. Give your pump time to cool down.

Float Switch
Ensure float switch is set to the correct height. A float switch ball set too high will cause the pump to shut off before the water is at the correct height. Bypass the float switch to ensure float switch is good.

Why does my sump pump keep running?

Connectivity Issue
Ensure your pump is plugged into your float switch’s piggyback connector, allowing the switch to activate your pump’s on/off switch.

Float Switch
Ensure the pit is clear of all float switch blockages and make sure to adjust the float switch ball to its proper seating via your owner manual.

Sitting Water
See “Why does my Sump Pump turn on but not move water?” above.

Too Much Water
Like any system, the pump can be overwhelmed. If your pit is constantly filling with water, but not overrunning, no real issue. However, you may wish to have another pump on hand in case your current one fails or overheats.

Laundry Soap
Some home sump pumps handle washing machine discharge. Soaps within the water can coat and fool the float switch electrodes. To prevent this, use a tethered style float switch.

Why is my sump pump so noisy?

Rattling Pipes
Insulate your pump pipe exits and joists with insulating foam or hang the pipe with a metal exhaust hook to prevent banging.

Check Valve
Ensure your pump is the correct horse-power for your needs. Pumps suction water and that water collides against the closed check valve when the pump shuts off, making a banging noise.

Pump Suction
Adjust the float switch to shut off before empty air suction begins.

Pump Vibrating
Indicative of a worn impeller. Replace missing or broken impeller blades and clear pit of debris.

Pump blows circuits

Electrical Interference
Water got onto your electrical cords or connections. Dry them out with a blow-dryer, then reconnect them.

Impeller Jammed
Remove impeller screen and clear of all obstructions.

Weak Cord
Not all extension cords are the same. Ensure yours is heavy-duty enough to support the horsepower of your pump.

Float Switch
Bypass the float switch and plug the pump directly into the electrical outlet. If it runs without blowing the breaker, your float switch needs to be replaced.

If these fail, your pump’s motor could have shorted. Replace the pump.