No Water Delivered
1 Priming – casing and suction pipe not completely filled with liquid.
2 Speed to low.
3 Discharge head too high.
4 Suction lift too high. The suction pipe may be too small or long, causing excessive friction loss.
5 Impeller completely plugged.
6 Intake strainer or suction pipe completely plugged.
7 Wrong direction of rotation.
8 Air pockets in the suction line.
9 Air leaks in the suction line and/or stuffing box (shaft seal).
Not Enough Water Delivered
1 Priming – casing and suction pipe not completely filled with liquid.
2 Speed to low.
3 Discharge head higher than anticipated. Check friction loss in piping
4 Suction lift too high. The suction pipe may be too small or long, causing excessive friction loss.
5 Impeller partially plugged.
6 Intake strainer or suction pipe partially plugged.
7 Wrong direction of rotation.
8 Air pockets in the suction line.
9 Air leaks in the suction line and/or stuffing box (shaft seal).
10 Foot valve is too small.
11 Suction not immersed deep enough.
12 Mechanical defects:
a) Wear rings worn.
b) Impeller damaged.
c) Packing of shaft seal damaged.
Not Enough Pressure
1 Speed to low.
2 Air in water.
3 Wrong impeller diameter.
4 Mechanical defects:
a) Wear rings worn.
b) Impeller damaged.
c) Packing of shaft seal damaged.
5 Wrong direction of rotation.
6 Pressure gauge in the wrong location.
7 Pressure gauge off calibration, broken or stuck.
The pump works for a while and then quits.
1 Leaking suction line.
2 Stuffing box packing worn or water seal plugged allowing leakage of air into pump casing.
3 Air pockets in the suction line.
4 Not enough suction head for hot water or volatile liquids.
5 Air or gases in liquid.
6 Suction lift too high.
7 Grass or trash sticking to strainer then floating off.
The pump takes too much power.
1 Speed too high.
2 Head lower than rating, pumps too much water.
3 Wrong direction of rotation.
4 Mechanical defects.
a) Shaft bent.
b) Rotating element binds.
c) Stuffing box too tight.
d) Wear rings worn.
e) Bearings are worn.
f) Casing packing defective.
g) Pump and drive unit misaligned.
Pump leaks excessively at the stuffing box.
1 Packing worn or not properly lubricated.
2 Packing incorrectly inserted or not properly run-in.
3 Packing is not the right kind for liquid handling.
4 Shaft scored.
The pump is noisy.
1 Hydraulic noise – cavitation, suction lift too high. Check with vacuum gauge.
2 Mechanical defects.
a) Shaft bent.
b) Rotating element binds.
c) Bearings are worn.
d) Pump and drive unit misaligned.
