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 over 12. 13.2 volts is considered fully charged

Pump is leaking

Pump seals need to be replaced

Regulator plunger is stuck because it is  dirty or damaged.

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 or 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 or damaged

Examine valves and clean or replace

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 a least a 3/4" hose

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 use a stronger unloader spring

Motor does not operate

Pump valves clogged or damaged

Examine valves and clean or replace

Motor has 12 volts, but does not run

If you have 12 volts at the motor,  the motor is bad or needs brushes

Leaks seen under pump

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

Worn pump seals

Replace with new plunger and seals

Regulator leaks fluid from cap

Abrasives in solution have damaged pump seals

Mix chemical thoroughly and improve filtration.Replace with new plunger and seals

 Pressure is set too low

Set pressure higher to keep internals from moving too much

 Worn plunger seal

Replaces 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. Flexible hose should be installed on 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
  • If temperature is above 130F, a pressurized inlet supply is required

If a tank is used:

  • 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 the bypass return. This will minimize air bubbles caused by agitation being drawing into the pump.
  • Check the seal of in-line filter because this can degrade and lose its seal over time.

Worn nozzle

The most common cause for low performance are worn nozzles and for this reason Pumptec recommends nozzles made from hard materials, not brass, are used with pumps. The erosive power of high pressure water is powerful and will increase nozzle size resulting in lower pressure.

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 nozzle.

Worn valves

As the pump operates, the valves can begin to degrade from exposure to chemicals, heat, cavitation and abrasives. The small pits in 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 if using harsh or abrasive chemicals.

Worn seals

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

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

Eroded pump body parts

If the pumps have been used with strong chemicals, hot fluids or problematic inlet conditions the pump body parts can become damaged resulting in leaks. Care must be taken not to run damaging chemicals through pump or allow chemicals to sit because they will dissolve the pump body parts requiring complete pump replacement.

Cracked manifold

The aluminum manifold is soft and can tolerate a certain amount of excess tightening, but it can crack and create a leak point. It is not necessary to over tighten fittings. Use of liquid thread sealant or PTFE tape sometimes allows for over tightening of fittings, so please be careful.

Pinched O-rings

During re-assembly, 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 afterwards.

Air leak in inlet plumbing

The integrity of connections needs to be maintained over time and this may require periodic inspection. Since many Pumptec pumps are used in portable equipment, plumbing systems can receive shocks that loosen connections and create leaks.

Leaky hoses and connections

Look for leaks from cracks in hoses or from connections of fittings. Over time these connection can become strained from handling and temperature changes.

Pressure gauge damage

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.

Regulator or unloader worn

This primary flow control device can be harmed from debris in the fluid or simply worn out from use. It is recommended that regulating valves and unloaders are replaced on a preventative schedule because some can fail in a dangerous way.

The debris-damaged or worn seals in an unloader can allow fluid to leak internally out the bypass port decreasing performance.

Grooving of plunger and seals

Most Pumptec pumps have stainless steel plungers’ standard. After extended use or pumping abrasive fluids, the plungers can become grooved. Plungers with grooving are not re-usable and need to be replaced. If a grooved plunger is allowed to run against seals, the seals will develop similar grooving and need replacement. For this reason, Pumptec packages plungers and seals together in kits because they should be replaced at the same time.

Excess fluid heat

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 the rated temperature of pump at any time, including idle time. Excessive fluid heat will transfer through plunger and require more frequent greasing to maintain lubrication.

Operating without enough fluid

Pinched hoses and clogged filters will starve the pump of fluid and damage seals as a result of excessive vacuum. Also, operating pump without any fluid can damage seals. Make sure adequate amounts of fluid are available to the pump at all times.

Recommended pump maintenance

The pump and bearing were lubricated with grease at time of production and it is not necessary to lubricate the pump other than at service kit replacement. At time of replacement of Kit A, we recommend installing approximately 1.5 oz. of grease in the plunger slot according to the picture below. Note the 3 separate places to apply .5 oz. of grease. After the pump operates most of the grease will be displaced from the slot and scattered inside the pump. This is normal and acceptable. Only a small film of grease is necessary to provide proper lubrication. If water or chemical is allowed to mix with the grease, the grease will no longer lubricate, turn into a black paste and create a failure.

Duty cycle, quality of fluid and environment will affect these service cycles. Every pump system is different and these differences can affect the pump life.

Often the most common problem is a loss in pressure. This problem can have many causes such as inlet restrictions, pump valve damage and worn nozzles. It is recommended that this quick troubleshooting check list followed:

  • Inlet plumbing does not have kinked hoses, clogged filters or collapsed fittings.
  • Pump valves are not clogged with debris or broken.
  • Verify nozzle is not worn or damaged.