We recently acquired Triple R Specialty!
Read the story about why we joined forces and what it means for hydrostatic testing customers.

Learn More X

Pump Trouble­shooting

Overcome Common Pump Problems to Obtain Peak Performance

Pumptec pumps are designed and manufactured to withstand rugged use and last for years. Operational conditions or other external factors like clogged nozzles or filters, worn seals, or pinched hoses may diminish performance over time. Use these pump troubleshooting tips to pinpoint and correct potential issues.

No water flow Tank is empty Fill tank.
Water valve turned off Turn water valve on.
Filter clogged Clean filter.
Hoses or tank clogged Check and clean hoses and make sure the tank has no sludge in the bottom. Make sure water is flowing at the pump.
Pump valves clogged or damaged Examine valves and clean or replace.
Pump has lost prime Follow priming procedure.
Low Pressure Battery charge is low Check battery voltage and charge as needed. Should be at least 12 volts. 13.2 volts is considered full charged.
Pump is leaking Pump seals need to be replaced.
Regulator is not operating properly Check the by-pass flow when you are spraying. It should not have much if any by-pass while you have the spray gun open. If you are seeing a lot of by-pass, back off the regulator pressure to clean or install a repair kit in the regulator.
Worn nozzle Replace nozzle with new one of same size.
Leak in high pressure hose or connections Check hose and connections.
Filter clogged Clean filter.
Pump valves clogged Examine valves and clean or replace as necessary.
Pump pulsates when in by-pass Air leak in inlet plumbing Check and repair any loose or cracked fittings.
Undersized or pinched by-pass hose Examine by-pass hose for pinch spots and make sure it is large enough, generally 1/2" to 3/4".
Pump pulsates when spraying Filter clogged Clean filter.
Spray PSI is too close to the by-pass PSI of the Unloader Either use a larger nozzle or if AMPS allow, adjust pressure up or use a stronger unloader spring.
Pump valves clogged or damaged Examine valves and clean or replace.
Motor does not operate Motor has 12 volts, but does not run If you have 12 volts at the motor, the motor is bad or needs brushes.
Motor does not have 12 volts Check current flow from the battery, circuit breaker tripped, fuse blown, 12 volts after the breaker, 12 volts after the switch, and 12 volts at the motor. Also check the ground wire and ground stud for good connection. Replace bad components.
Leaks seen under pump Worn pump seals Replace with new plunger and seals.
Abrasives in solution have damaged pump seals Mix chemical thoroughly and improve filtration. Replace with new plunger and seals.
Regulator leaks fluid from cap Worn plunger seal Replace seal.


  • Insufficient fluid supply, or starving, to the pump inlet is one of many causes of low pressure. To avoid starving the pump:
    • Verify all valves are open in the supply line before starting your pump
    • Check for line restrictions and minimize plumbing fittings like elbows
    • Verify the inlet line is at least the size of the pump inlet port, ideally one size larger
    • Avoid Rigid Plumbing. Reinforced flexible hose should be installed on the pump inlet
    • Properly seal all connections with PTFE tape or sealant for sealed connections
    • Confirm your liquid temperature is within the maximum limits of the pump, less than 140°F


  • Connect the supply line from supply tank to the pump above tank bottom to avoid picking up any settled debris
  • The pump supply line from the tank should be plumbed from the opposite side of the tank than where the bypass return is located. This will minimize air bubbles caused by agitation being drawn into the pump
  • Check the seal of the in-line filter because this can degrade and lose its seal over time


The most common cause for low performance is worn nozzles. Pumptec recommends that nozzles made from hard materials, not brass, should be used with our pumps. The erosion resulting from high-pressure water is powerful and will increase nozzle size, which will result in lower pressure over time.

Avoid the common mistake of adjusting the regulator bypass pressure higher to compensate for lower spray pressure. If increasing adjustment does not increase spray pressure, then replace the nozzle.


As the pump operates, the valves can begin to degrade from exposure to chemicals, heat, cavitation, and abrasives. The small pits in a valve disc or seat will allow small amounts of fluid to leak during each compression stroke and result in less flow going out the nozzle. A preventative maintenance schedule needs to be followed, especially when using harsh or abrasive chemicals.


The primary causes of water leakage are worn seals. Causes of worn seals include wear over time, lack of proper maintenance, abrasive fluids and excessive heat. It is important to monitor pump systems to determine causes of wear and fix them. Pumptec’s seal designs will reveal worn seals in the form of drips below the pump. The leakage would need to be substantial to noticeably affect performance. To prevent seal damage, avoid:

  • Running dry
  • Abrasive chemicals
  • Hot fluids
  • Starvation
  • Unfiltered water


During reassembly, an O-ring can slip out and become pinched permitting water to leak out. It is typically necessary to replace a pinched O-ring because they become misshapen and will not seal properly afterward.


The integrity of connections needs to be maintained over time and this may require periodic inspection. Look for leaks from cracks in hoses or from fitting connections.


Occasionally pressure gauges can become fatigued and damaged causing malfunction. A good diagnostic practice is to replace the pressure gauge with a known good gauge as a check.


This primary flow control device can be harmed from debris in the fluid or simply worn out from use. The debris-damaged or worn seals in an unloader can allow fluid to leak out the by-pass, decreasing performance.


Most Pumptec pumps have stainless steel plungers standard. After extended use or pumping abrasive fluids, the plungers can become grooved, damaging the seal. Plungers with grooving are not reusable and need to be replaced. Pumptec packages plungers and seals together in kits because they should be replaced at the same time.


When excessively high temperature fluids are run through the pump, the seals and elastomers can become deformed and fail. Proper care must be taken to not exceed 140°F fluid temperature in the pump at any time, including idle time.


Pinched hoses and clogged filters will starve the pump of fluid and damage seals as a result of excessive vacuum. Operating the pump without any fluid can increase seal temperature and damage seals. Be sure you always have adequate amounts of fluid available to the pump.


Follow recommended Service schedules.

Existing Pumptec customer?

Visit our Customer Support Page

Need help finding the right pump?

Connect With a Pump Expert
OR CALL 763-433-0303