Common Pump Problems and Troubleshooting Guide

May 24, 2018

No job is perfect. All industrial equipment has the potential for failure and things going wrong. Here’s how to troubleshoot the most common issues that happen with pumps and pump equipment. Sometimes pumps will wear out, often for a variety of factors. A lot of the wear and tear can be minimized through routine maintenance of critical components and replacing them when a problem is spotted.

No Liquid Being Pumped

Potential CauseHow to Fix
Pump is not primedEnsure the pump and volute are completely full of liquid before operating the pump. If any air is trapped in the pump, it will not operate correctly.
Pump loses primeCheck for leaks in the pump, pipeline, and couplings which could cause air to enter the pump. If you suspect air in the pump, make sure to vent volute/casing to remove trapped air before resuming pumping.
Suction lift is too highCheck the pipeline for friction losses and ensure the static lift is not too high. If the static lift is too high, you’ll need to lower the pump closer to the source material or raise the material closer to the pump.
Suction line is cloggedRemove obstruction.
Static discharge head is too highCheck pipe friction losses, use larger discharge pipes.
Rotor speed to lowEnsure the motor is receiving the required voltage and correct frequency if using a variable frequency drive.
Rotor spinning the wrong directionCheck the motor rotation direction as indicated by arrows on the pump casing. Make sure the rotor is spinning in the correct direction when the pump is in operation.
Rotor is clogged or jammedDisassemble the pump and volute to clear the rotor jam or clog.

 

Flow Rate is Too Low

Potential CauseHow to Fix
Air leaks in the suction hoseIf liquid pumped is water, test flanges for leakage with flame or match. For such liquids as gasoline, the suction line can be tested by shutting off or plugging inlet and putting the line under pressure. A gauge will indicate a leak with a drop of pressure.
Air leaks in the stuffing boxIncrease the lubricant pressure to exceed atmospheric pressure, effectively locking air out of the stuffing box.
CavitationCheck NPSHr and NPSHa, you may not have enough positive suction head for what is required.
Defective rotorOpen up the pump and volute casing to inspect the rotor for damages. If the rotor has been damaged, ensure it is repaired or replaced prior to powering on the pump.
Defective packingInspect and replace packing if sufficiently worn.
Rotor spinning the wrong directionEnsure the rotor is spinning in the correct direction by comparing it with the indicator on volute. A rotor or impeller spinning in the wrong direction could damage the pump.

 

Low Suction

Potential CauseHow to Fix
Clogged suction strainer or inletClean out the strainer and ensure it is free from obstructions which could clog the suction inlet.
Insufficient hydraulic fluidEnsure the pump motor is filled to proper hydraulic fluid levels. Consult the manual for your hydraulic equipment for proper fluid levels.
Leak in the suction pipeline or hoseInspect and repair pipeline or hose for leaks.
Insufficient suction pressureRaise the liquid tank level closer to the pump.
Worn check valvesClean or replace broken or worn-out valves to ensure proper operation.

 

Pump Motor Won’t Start

Potential CauseHow to Fix
Blown fuse or breakerClean out the strainer and ensure it is free from obstructions which could clog the suction inlet.
Starter overheatingCorrect cause of thermal overload and reset the motor.
Low line currentInspect lines and fix the problem.
Motor damagedCheck for physical damage to motor, repair, or replace as needed.

 

Pump Motor Overheating

Potential CauseHow to Fix
Operating motor in excess of ratingLimit discharge pressure to max specified by the motor manufacturer.
Improper wiring or voltage too lowCheck power supply vs motor nameplate details for correct specs.
Hydraulic oil too viscousDrain and refill with the correct type of oil.
High ambient temperaturesIncrease ventilation or relocate pump to a cooler area.

 

Pump Periodic Maintenance Routine

DailyCheck temperatures.
Check cavitation & bearing noise.
Check motor current and voltage.
WeeklyCheck suction & discharge pressures.
Check vibration & noise.
Visual check for seal leakage.
MonthlyRemove the safety guards and inspect the pump shaft.
Check for coupling alignment.
Fill lubrication oil.
AnnuallyIf the pump is a spare, run the pump and check for any maintenance issues.
Check for any axial movement of the motor shaft.
Remove and clean all auxiliary components including valves, manometers, pipes, and hoses.
Remove couplings and inspect for wear on rubber parts.
Every 2 Years or 10000 HoursDismantle pump and inspect: impeller, wear rings/plates, O-rings, pump shaft.
Apply coating to un-machined surfaces.

Need Help?

Our team of engineers is standing by to help you with your next project. Call us at (760) 821-8112 or submit a request.

Need Help?

Our team of engineers is standing by to help you with your next project. Call us at (760) 821-8112 or submit a request.