Troubleshooting Pumps

by Diane Calabrese |Published March 2025

 

Pumps get all the blame. Okay, not all, but they often become the first suspect, especially when the person doing the troubleshooting is the opposite of a pump expert.

For example, a solar-powered pump in a little pond stops running. Detach,  clean algae from the filter, reconnect, and orient the solar panel to full sun, and then you get some action but not much. The long (real) story short is that the pump worked, but the panel had gone bad. Solar panels do not last forever.

Let’s say it is the pump, though. How do you begin to (safely) troubleshoot? We asked  a few questions to three experts on pumps. Some nuggets of what they tell us are as follows:

First, person A may hear something that sounds like a knocking rod while person B may be reminded of marbles clattering, but whichever way the sound registers in the brain, it’s time to pause and evaluate the pump.

Second, attend to all of the easy stuff—starting with routine maintenance—but also keeping kinks out of hoses, using a clean water source, and orienting filters correctly, and the pump will serve as designed.

Third, pump manufacturers and distributors offer abundant information about their pumps such as their designs, functions, and maintenance. Use it. Never guess.

Fourth, by checking the filter first, this writer did something correctly when her solar-powered pump stopped working.

 

Expert Advice

Our three respondents are Adam Leyendecker, Inside Sales/Customer Service Manager at Valley Industries—Comet Pump^®, Paynesville, MN; Derek Majewski, CFPS, Marketing & Business Development Specialist, Cat Pumps Corporation, Minneapolis, MN; Robert Piedade, Director of e-Commerce, A.R. North America Inc., Fridley, MN.

 

 

Cleaner Times (CT): Is there a noise, odor, or other sensory cue that should signal danger and immediate cessation of pump use?

 

Leyendecker: If the pump needs maintenance, there can be several factors that can make you aware of what needs to be done. Factors include visual, audible, and olfactory.

Visually, there can be leaks under the pump to make you aware of a leaking water seal. Or there can be a milky white or gray color to the oil indicating a leaking water and oil seal. Or there can be water/oil coming out of the breather plug indicating several internal issues.

Audibly, the most common symptom is a sound coming from the check valve chambers on the front of the pump. This usually indicates a stuck or broken check valve. Another audible clue is a grinding or banging noise coming from the crankcase of the pump. This can be caused by a bearing or connecting rod failure, and there could be a surging sound coming from the motor. This sound can indicate several things, but the most common is a stuck valve.

Odor—If there is an odor coming from the pump, there needs to be an inspection. An oil smell can indicate an oil/water mix. A burning/smoking smell can indicate low oil in the crankcase. A melting rubber smell can indicate the pump being run without water.

 

Majewski: One significant safety concern when operating a high-pressure pump is excessive pressure. A pumping system should always have a primary pressure control valve, such as an unloader or regulator, and a secondary valve, like a relief or pop-off valve. These valves protect the operator and the pumping system from over-pressurization by relieving water once the pumping system reaches the set pressure point. If these valves are not functioning correctly and the operator notices an increase in pressure above the normal operating range, they should stop the pumping system immediately.

Continuing to operate under the conditions just described can lead to further pressure buildup, potentially causing damage to the pump, the operator, or anyone else nearby if a part of the system fails due to over-pressurization.

 

Piedade: Two examples are cavitation and an unloader not unloading on a gasoline engine. Cavitation caused usually by a lack of water or air entering the pump will give a rod-knock sound—banging—as if coming from the pump-drive end. So, if you close the spray gun and do not notice a change in the engine’s tone, odds are the unloader is regulating and not unloading. The danger in this is the bypass water is being pinched and will have high friction going through the ball and seat of the unloader, and the water will have a very rapid temperature increase (i.e. 70 degrees F to 145 degrees F in as little as 45 seconds). Over a short time, pump damage will occur.

Another way to tell if the unloader is not unloading is if you have a pressure gauge in the head of the pump and release the spray gun trigger. When the trigger is released,  the gauge pressure should drop to about 80 psi.

 

 

CT: Is there one issue with a pump that is so minor that any pump user should be able to identify it as a problem and resolve it?

 

Leyendecker: One of the most common calls is “low pressure,” which can be caused by many factors, but the most common is  a stuck valve. It can be caused by many things, like hard water deposits, chunks of rubber from the garden hose getting pulled into the pump, or parts of the seals moving into the valve chambers. These can easily be resolved in most cases by taking the valve cap off each chamber and cleaning it out and putting it back together. Most of the time the valves don’t even need to be replaced.

 

Majewski: One common pumping issue that is easy to identify is cavitation, which can occur from a restricted inlet or a small air leak on the inlet. Cavitation can present itself as a knocking noise that may sound like a bag of marbles in the drive-end of the pump.

The damage from cavitation is caused by small micro-implosions from instantaneous changes in pressure while the plungers are reciprocating. It can damage the surface of the plungers, valves, seats, and more of the pump with continued operation.

If the operator hears a knocking noise, the best action is to review the entire inlet section of the pumping system from the water source to the pump’s inlet. Things to look for include a clogged inlet filter, sticking check valves, kinked inlet hoses, or fittings that may have come loose and are allowing air to be sucked through the threads. After reviewing the inlet, allow water to flow through the pump to remove air pockets.

A common issue with pressure washers is sudden and intermittent pressure loss. Many gas-engine pressure washers feature an easy-start valve designed to relieve pressure in the pump, making it easier to start the engine. However, this valve can often become stuck in the open position, causing it to continuously bypass and prevent pressure from building up. Tapping on the easy-start valve with a hammer or wrench can often free the internal ball. If that doesn’t work, disassembling and cleaning the valve can free the ball, allowing the pressure washer to function again.

If the operator observes water leaking from the pump, the most common issue is worn or damaged pump seals. This leak is often accompanied by low pressure, which occurs when water leaks internally past the seals. To resolve both the leak and low pressure, it is usually necessary to replace the seals with a new seal kit. Additionally, during maintenance, it is important to inspect the other components inside the pump and replace any essential parts as needed.

 

Piedade: A plugged/dirty inlet filter is one minor issue. Most pressure washers use cone-style inlet filters. Most garden hoses lie in dirty conditions, and the operator rarely flushes them before connecting them to the pump.

The other issue with cone filters is they can be installed backwards. The proper way is with the point of the cone towards the feed hose. Proper orientation allows any dirt that enters the system to wash down the side of the filter.

 

 

CT: Does your company offer easily accessible guidance for a contractor who wants to troubleshoot pumps?

 

Leyendecker: Troubleshooting and breakdowns can all be found at our company website under the support tab. A customer support team takes calls for those with additional questions.

 

Majewski: The service and training section at our website includes FAQs, troubleshooting guides [including those specific to pressure washers], service videos, and informative whiteboard sessions videos. Technical support specialists can be reached via phone and email.

 

Piedade: Our website offers immediate links to technical support—troubleshooting, manuals, parts breakdowns, and contacts for how we can assist you.

 

 

Suspect Roundup

 

Don’t suspect any one thing. Suspect everything. (Follow the dictum of Inspector Clouseau in A Shot in the Dark (1964) who declares, “I suspect everyone, and I suspect no one.”)

As bumbling a detective as Peter Sellers’ Clouseau character was, he got the procedure correct. A detective—or a troubleshooter—must try not to be thrown off the true culprit’s trail.

Troubleshooters are open to all clues about what’s happening or not happening. A tweak, such as straightening a kinked hose, may be all that’s needed so that a pump quietly purrs again. But always verify that operational norms—e.g., pressure—are back.

Reliable pumps are a must in pressure washers. If a pump falters or fails, the machine it supports cannot be used, and a contractor sustains a loss of time and money.

Manufacturers and distributors are true partners with contractors in our industry. They do everything they can to ensure contractors can get the maximum life and top performance from the pumps they make and sell, respectively. That includes sharing the maximum amount of information on design and function. Take advantage of the information.

And as an end user, be a good detective should the need for troubleshooting occur. Don’t jump to the conclusion that it’s the pump. Consider all the suspects.

Although the pump may be the suspect, it is sometimes not the culprit when shimmies, sounds, or odors signal something has gone amiss. Troubleshooting has a lot in common with detective work. The place to begin is by being open to all possibilities with a commitment to assess a situation in a methodical way and without jumping to conclusions.

Optimally functioning pumps are second only to available water when there is serious work to be done. As we write, there are pumps, but there is insufficient water to fight the fires in Los Angeles County.

Water itself has a role to play in generating the pressure needed. Water mains break, water towers topple, and utility workers accidentally sever lines. Still, as long as there are abundant water resources available and reliable pumps (and pumping systems), things can be made right.

In the big scheme of things, when end users work with distributors, and manufacturers in our industry work collaboratively to demonstrate how maintenance gets done—and gets done well—they are setting an example. A good example, which everyone in industry, commerce, and society should be setting.