If you manually forced the drainage pump installed in the sump pit to run and hear the motor operating sound but no water comes out, and even after removing the discharge flange there is no discharge, then rather than a simple blockage in the discharge piping, you should first check the pump body, impeller, rotation direction, and suction part.
Especially if the pump is fully submerged in water and you run it after removing the discharge flange but no water comes out from the pump discharge outlet at all, the possibility of a problem with the check valve or downstream piping is quite low.
Inspection Order |
Suspected Cause |
Symptoms Observed On Site |
How to Check |
1 |
Impeller blockage | Motor sound heard but no discharge | Turn off power and check if debris, fibers, or plastic are wrapped around the impeller |
2 |
Impeller detachment or damage | Motor rotates relatively easily but no water comes out | Disassemble and check the connection between impeller and motor shaft |
3 |
Motor shaft free spinning or coupling problem | Motor sound is normal but no actual pumping action | Check if the shaft and impeller rotate together |
4 |
Three-phase motor reverse rotation | Rotates but discharge volume is very low or almost none | Check rotation direction and verify phase sequence |
5 |
Suction inlet blockage | Motor runs but cannot draw water | Check for blockage at the pump’s lower suction inlet and strainer |
6 |
Severe impeller wear | Rotation is normal but no head or flow generated | Check the clearance between impeller blades and casing |
7 |
Air lock | Air trapped inside the pump causes poor discharge | Check pump position, vent openings, and water level |
8 |
Insufficient water level | Pump suction part is not sufficiently submerged | Verify actual sump water level and minimum operating water level |
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