Vertical Pump Troubleshooting

Symptom Probable Cure

Pump does not pump.

Check Liquid level
Note:  If pump is air locked it will run and not pump.

Pump runs but flow is reduced.

Check rotation
Note:  Flow and head will be greatly reduced when operated in reverse.

Pump starts pumping but flow falls off.

Liquid level changes after start-up.
Note:  The impeller (located at the bottom of pump) must always be flooded.  If at any time the liquid level falls below the impeller, pump may lose suction with reduced flow.

Liquid is running out the overflow.

Pump discharge valve may be closed or system head too high.

Pump is vibrating.

Check suction condition.
Note:  The pump suction must never be restricted.  The suction line should generally be as short and straight as possible.  The suction side valve should never be closed or partially closed during operation.