How to Troubleshoot a Lift Pump for Residential Sewage

Residential sewage lift pump systems are designed to force the sewage up onto higher ground instead of pulling the sewage down into lower levels. The lift pump system is connected to an underground hole where the sewage enters from the residential pipe, and the pump is activated once the sewage hits a pre-determined level in the hole. Sewage then moves through the sewer force main pipes and into a gravity manhole before being transferred to a water treatment facility. Troubleshooting common problems with a residential sewage lift pump system can often help owners fix the problem prior to calling for service.

Residential sewage systems eventually connect to a local water treatment plant.

Step 1

Check the circuit breaker or fuse connected to the sewage lift pump if the pump is not operating and replace or reset the circuit breaker or fuse as needed. Turn the primary lift pump power switch to “On” if the circuit breaker or fuse is working. Look at the owner’s manual or contact the sewage pump manufacturer to determine the necessary line voltage for the sewage pump, as low voltage may cause the pump to malfunction. Most residential sewage lift pumps require at least 120 volts and a three-prong grounded electrical plug.

Step 2

Wait for water to cover the top of the pump if the system has power but is not running. Press the reset button on the pump if the pump has overloaded or the relay has tripped. Note that most pumps require the liquid level to reach at least 13 inches from the bottom of the basin floor. Do not utilize the sewage pump for water over 120 degrees Fahrenheit.

Step 3

Connect an ohm meter to the pump motor leads and windings and check for resistance if the overload heaters are tripping and the pump will not start. There should be similar ohm readings on all phases. Contact an authorized service professional if the readings are off or there is no resistance, as the motor may need to be replaced.

Step 4

Remove the pump from the sump if there is proper resistance but the pump continues to fail. Remove the impeller housing and clean the impeller, which looks like a fan. Remove any objects that may be blocking the impeller from moving properly.

Step 5

Inspect the pump bearings if the pump system is vibrating or making excess noise. Replace any worn bearings. Check the impeller housing for debris and clean as necessary. Note that the pipe attachments to the residence may make noise if the attachments are too firm or too loose. Pipes with flexible connectors are best.

Step 6

Turn the selector switch to “Auto” and turn off the primary power if the pump does not operate automatically but will operate when the selector switch is set to “Manual” or “Hand” setting. Connect a jumper wire to the terminal strip and turn on the primary power. Replace the float control or contact the pump lift manufacturer or another qualified service professional if the pump starts.

Step 7

Shut off the primary power on the pump if the system is running but does not shut off automatically. Set the selector switch to “Auto” instead of “Manual” or “Hand”. Allow the system to sit for at least 10 minutes, then restart the power to release an air lock. Move the lower float control if the control is stuck in position, until the control moves easily.

Step 8

Open the discharge gate valve fully if the pump is not moving at full capacity. Clean out the discharge gate valve and raise the check valve level up and down to clear the valve. Turn off the pump, wait a few minutes, and restart the pump to ensure the pump is not running in reverse. Open the shut-off valve if the valve is closed.


  • Do not attempt to service or troubleshoot the sewage lift pump if you are not confident that you can perform the task accurately and safely. Contact the lift pump manufacturer or another qualified service professional instead.