Pump Troubleshooting Guide

This pump troubleshooting guide can help with your common pumping concerns. Understanding the cause and remedy of your pump issue, along with some simple preventative steps, you can get back on track with smooth hydraulic metering pump operation.

Many metering pump issues are due to the set-up or other factors in the system as a whole, as most manufacturers, like JAECO, test every pump before shipment to ensure proper function. However, many of the problems mentioned here are easy to correct.

What follows are a few of the more common problems pump users face. If you can’t find your issue or you have any questions, contact one of our experienced technicians for assistance.

Click one of these links to jump straight to the issue (then scroll up slightly):

Pump Troubleshooting – Location Suggestions

When choosing the location for your pump, always read the manufacturer’s instructions and recommendations. Pump location can cause many issues, especially if it’s exposed to extreme temperatures or too far from the supply vessel.

Choose a firm, level surface accessible for routine maintenance. If possible, place suction connection below the supply liquid level to create full flooded suction.

Keep in mind the weather conditions the pump will be exposed to. If it will face freezing temperatures, consider a solution to prevent freezing chemicals. If it will get wet, ensure any added electrical connections are watertight.

Suction Pumping Malfunction

Most metering pump operation problems are due to suction piping or blockage issues. One note when choosing suction pumping for a reciprocating pump is that the pulsating nature of the pump requires pumping that can handle its peak instantaneous flow. This is usually about three times the rated pump capacity, so check that your pipe size is enough to handle the flow. Try to keep suction lines as short and straight as possible. If necessary, slope them to avoid vapor pockets.

Issue: Suction Pumping Malfunction

Cause Remedy
Clogged or dirty suction strainer Clean suction strainer
Not enough hydraulic oil Add hydraulic oil until filled to the proper level
Suction piping is leaking Locate leak in the pipe and repair
The relief valve is leaking (internally or externally) Reset leaking relief valve
Not enough suction pressure Increase the level in the liquid tank
Check valves are worn out or dirty Evaluate check valves and clean or replace as necessary
The liquid is nearing the boiling point Either cool the liquid or increase the suction head
Liquid has a viscosity that’s too high Reduce the liquid’s viscosity and change the ball material and/or size


Issue: The Pump’s Motor Won’t Start

Cause Remedy
Fuse is blown or breaker is tripped Determine and fix the cause of the overload and replace the fuse/reset the breaker
The motor starter has an open thermal overload Determine and fix the cause of the thermal overload, then reset the thermal overload. If the motor still won’t start, evaluate the heater size.
Line current is too low Fix the cause of the low line current
A control device in the pump motor starter circuit has an open circuit Reset any open circuits in the pump motor starter
Damage to the motor Evaluate the motor for any damage that may prevent proper operation


Issue: Pump Doesn’t Deliver When Running

Cause Remedy
Not enough hydraulic oil Add more hydraulic oil until filled to an adequate level
Solids lodging open check valves lodged Evaluate check valves and clean or replace as necessary
Check valves are worn out or dirty Evaluate check valves and clean or replace as necessary
Blockage in suction or discharge line Remove blockage by cleaning the line
Closed isolation valve Open the isolation valve
Unprimed pump Before pumping against pressure, fill suction line and pump head with liquid
Improperly installed check valves Evaluate the installation of check valves. Remove and reinstall relevant valves properly.
Diaphragm and contour plate have solids built up between them, which prevent diaphragm movement Remove liquid end. Clean liquid end and replace the diaphragm.


Issue: Pump isn’t delivering rated capacity

Cause Remedy
Wrong capacity setting Change capacity setting
Not enough hydraulic oil Add hydraulic oil until filled to an adequate level
Suction is starved Increase the size of the suction piping or suction head
Relief valve (internal or external) keeps relieving because it’s set too low for the system Check the pump rating and adjust relief valves to the proper setting
Suction piping is leaking Determine and repair the cause of the leak
Suction lift is too much Decrease suction lift
The liquid is nearing the boiling point Either cool the liquid or increase the suction head
Liquid has a viscosity that’s too high Change ball material or size and reduce the liquid’s viscosity
Check valves are worn out or dirty Evaluate check valves and clean or replace as necessary


Issue: Erratic Pump Operation


  • Don’t use pipe smaller than the manufacturer-supplied suction connection
  • Properly support piping to not strain pump connections
  • Install a properly-sized screen in the suction line to prevent debris from entering the pump
  • Always flush the suction piping before connecting the pump
Cause Remedy
Suction connections are too small Replace connections with larger components
Debris in the supply tank, piping, or check valves Disconnect and flush the piping, pump, and check valves and install a properly sized strainer


Issue: Pump is Delivering too Much Capacity

This is usually due to insufficient discharge pressure or too much suction pressure. Try to increase your discharge pressure (a note: to ensure proper check valve operation, your pump discharge pressure should be 15-30 psi more than your suction pressure).


Issue: Check Valves are Noisy When Operating

Cause Remedy
Excessive wear on gears Repair gear set
End play in motor shaft Reshim shaft
Wrong lubrication Lookup correct oil and replace
Bearings are worn out Replace bearings with new ones

Ball valves make a clicking noise during operation and may also make a rattling noise amplified by the pipe. This is normal and shouldn’t be concerning.


Issue: Overheating Motor

Cause Remedy
The pump operated over its discharge pressure rating and the motor was overloaded Keep discharge pressure within the range specified
Low voltage or otherwise improper wiring Check the motor nameplate data and be sure the power supply matches
Vicous hydraulic oil  Drain current oil and refill with the correct, less viscous oil
Ambient temperature is too high Evaluate pump location and take measures to ventilate, protect it from the sun, or relocate


Issue: Oil Leaking From Pump

Cause Remedy
Loose oil plug Tighten oil plug
Too much oil in the pump Drain out the excess oil until it’s at the proper level
The breather cap is either too loose or missing Tighten or replace breather cap
The diaphragm head bolts are not tightened Tighten diaphragm head bolts to specifications


Issue: The Hydraulic Oil is Discolored or the Pump is Losing Oil

When pump troubleshooting, this issue is most frequently caused by a ruptured diaphragm. Replace the diaphragm after fixing the cause of the rupture. When this happens, you must discard the hydraulic oil and thoroughly flush the gearbox. Replace with fresh hydraulic oil.


Discharge Pipe Tips

  • For long pipe runs, install a pulsation dampener as close to the pump discharge connection as possible to avoid the hydraulic shocks known a “water hammers”
  • Ensure your discharge pipe is a good size for your application and pressure setting
  • Avoid undersized pipe adapters in the discharge line that might restrict flow


Auxiliary Equipment Warning

Accessories such as backpressure and safety relief valves, pulsation dampeners, and more may be causing the issues you’re experiencing with pump performance. Ensure that all are accurately sized and installed. If unsure, contact pump and accessory manufacturers for advice on compatibility.


Pump Troubleshooting – Preventative Steps

With some simple preventative steps, your pump can run smoothly without needing a pump troubleshooting guide. Start by reading your manufacturer’s manual and any installation and operation instructions. A pump properly set up, in the beginning, will be free from several issues.

Establish some preventative maintenance practices, like checking oil levels and seal integrity semi-regularly. Keep some spare parts, like check valves, on hand for easier fixes in the future.

Only use your pump for the application for which it was designed. If you need to change the application, contact your manufacturer to check if the new chemicals are compatible with pump materials and design.

When choosing your pump, ask questions and provide lots of information to your manufacturer. That’s how they can help you choose the best pump for your application. Properly matched components, materials, and installation are the key to smooth pump operation.

If you didn’t find what you need in this guide, contact our experts for advice on your pump problems.


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