It is the most common service call of all: the pump hums, everything sounds normal, and nothing comes out of the tap. In roughly that order, here is where the problem almost always lives.
1. Lost prime
A surface pump with air in its casing moves air, not water. Refill the casing and suction line through the priming port, then restart. If it loses prime again, you have an air leak; go to step 3.
2. Foot valve or strainer blocked
The non-return valve at the bottom of the suction line clogs with leaves, silt and scale. Pull it and look. A blocked foot valve is the single most frequent find on this call.
3. Air leak on the suction side
A dripping joint on the suction line lets air in without letting water out, so it never drips visibly and everyone misses it. Check every fitting between water surface and pump inlet. Smear suspect joints with water and watch for bubbles being drawn in.
4. Water level dropped
Wells draw down in dry seasons. If the intake now sits above the water, no priming will help. Confirm the actual water level before condemning the pump.
5. Closed or seized valve
A suction or discharge valve that looks open but has sheared internally. Open and close it fully and watch the pressure gauge respond.
6. Wrong rotation
On three-phase motors, two swapped wires spin the impeller backwards: it runs, sounds normal, and pumps a fraction of its rating. This follows every recent electrical repair until proven otherwise.
Work the list in order and you will find it before lunch. When the pump truly is the problem, it usually tells you earlier with noise or heat, not silence.