Troubleshooting a Metering Pump

A metering pump is rather easy to fix, but to troubleshoot the device, it is important to determine if the location of the pump is not the one causing problems. If the pump is installed in a location that exposes it to extreme temperature and moisture conditions, it may be better to re-install it to a more convenient and safer location. Here are some troubleshooting tips you can follow before deciding to call in a professional.

General Troubleshooting Guide

If the metering pump is not working properly, some of the most common causes include low levels of hydraulic oil, clogged check valves and suction line, and insufficient NPSH. Double-check the levels of hydraulic oil and fill it to the correct level. Inspect the check valve and suction line. Clean any trapped debris inside them. If they are damaged, disassemble them from the system and replace them with new ones.

If the NPSH is insufficient, increase the size of the suction head and the suction lines. In addition, reconfigure it to become as simple as possible by shortening the piping to enhance performance.

Difficulties in the Suction System

Most problems in the pump are related to the suction system. The pipes may be undersized, blocked, or leaking. Ensure that pipework is kept short and straight. Check the suction strainer and remove any trapped debris. If the suction pipe is leaking, remove the pipe and replace it.

Reset the valve if there is insufficient suction pressure. Check the temperature of the liquid. If the temperature is very close to boiling point, either increase the suction head or reduce the temperature of the liquid.

Pump Motor Does not Start

A pump motor that does not start may be caused by a blown fuse, a tripped breaker, motor starter thermal overload, or reduced current. To correct the issue, unplug the pump, let it rest for a few minutes and reset. If the fuse is blown, replace it with a new one. If you are using a circuit panel, check the circuit breaker and ensure that it is switched on. It is best to have a dedicated circuit breaker for the pump. Fix the circuit by wiring the pump to a new breaker. Inspect the motor for signs of damage and service any damaged parts.

No Discharge

The pump may fail to discharge liquid if there is insufficient hydraulic oil, check valves are clogged or worn out, suction lines are blocked, the isolation valve is closed, or the pump is not primed. Fix the issue by maintaining correct oil levels. Inspect the valves, clean any clogged debris or replace them if they are worn out. Clean the suction lines as well and open the isolation valve. Remove the liquid from the system and reintroduce new liquid.


If the motor overheats, reduce the pressure to the recommended maximum settings. Check the voltage on the wiring. If it is too low, rewire the system correctly. Determine if the location of the pump is causing overheating. Relocate the pump or increase the ventilation in the current location.