Why Read This Article?
Water flows through these major parts of a pressure washer:
1. The inlet, inlet hose, and inlet valve.
2. The intake filter.
3. A regulator.
4. The power pump.
5. Out the outlet valve and outlet hose.
6. Out the gun and pressure nozzle.
7. The unloader valve redirects water from the pump when the gun is not in operation.
Diagnosing usually follows this order:
This article explains what pressure washer users need to know to maintain and diagnose pressure washer performance issues.
Pressure washers are extremely useful when they're needed, as most most owners of pressure washers know, but the sensitivity of their systems also makes them prone to setbacks.
Owners of pressure washers often report symptoms that are difficult to diagnose, like low pressure, high pressure, no pressure, surging pressure, and pump issues. Pressure washer symptoms are difficult to diagnose because each symptom can be caused by more than one problem in almost any area of the washer.
Even though investigating a pressure washer performance issue can be a little tedious, getting to the bottom of the problem is just a matter of time and eliminating possibilities with a thorough inspection.
This article provides information that most pressure washer owners need to understand about how pressure washers work. It also explains steps for diagnosis of major pressure washer symptoms, starting with the most likely, most easily fixed possibilities. And it also explains how to prevent most washer problems.
The truth is that some pressure washer service issues just require professional help, and sometimes diagnosis can be next to impossible. But, the steps in this article will help users quickly determine if their diagnosis has hit a dead end, if it needs to go to a shop, or if it's just something simple like cleaning a valve.
Most pressure washer owners really love their pressure washer, which shouldn't be surprising. Pressure washers can easily take care of what would otherwise be tedious, backbreaking, hard-to-reach, or impossible cleaning jobs, and they use minmal water to do it.They're actually rather remarkable tools.
However, pressure washer systems are also very sensitive. Any kind of obstruction or addition of air can sharply decrease a washer's performance and/or damage parts. On top of that, most problems present with the same symptoms.
Being familiar with and understanding the major parts of a pressure washer system is very important to diagnose washer problems.
Here is a short list of the major parts of a pressure washer common to most designs:
1. Water enters the system's inlet, though its inlet hose and inlet valve.
2. Before entering the pump, water is filtered through an intake filter or screen.
When a pressure washer is in operation but the gun trigger is not depressed, something must be done with the pressurized water coming out of the power pump, since it's not exiting the system:
7. Unloader valves are another important part of every pressure washer.
Those are the major pressure washer parts, and understanding what they do is pretty simple enough. The catch is that pretty much everything has to go just right in a pressure washer for it to perform up to its design specifications.
Seals and valves must stay air-tight and clean, the water path must remain completely unobstructed, the washer must be receiving enough water from its water source (usually 1 GPM more than its rating), lubricated parts must stay lubricated, and the oil needs to be fresh and and full.
Maintaining a pressure washer to prevent performance problems goes a long way, but, eventually, a pressure washer is going to get an obstruction, air in its system, or see some wear on its parts.
Before moving on to diagnosing specific symptoms, it might help just to list the intrusions and conditions that kill a power washer's performance.
Lack of Power-
Like any other machine, the wrong power supply will greatly effect its use. Power supply is the first and easiest thing to check when water pressure drops.
Insufficient Water Flow-
Each pressure washer is rated to operate at a specific rate of water flow. This is usually expressed in GPM (gallons per minute). When not sure, users should check that they are operating their pressure washers at the correct GPM by checking their owner's manual. Sometimes a performance issue is that simple.
Any kind of dirt or build-up in a pressure washer is bad. This means in the intake hose, around the intake valve, around the regulator, in the pump valves, around the unloader, in the unloader hose, in or around the outlet hose and outlet valve, in the gun, and in the gun nozzle. In other words, the entire path of water through the machine must be dirt and build-up free.
Gunky valves and valve O-rings will decrease performance and increase wear on components. If dirt somehow gets into the pressure pump, the pressurized conditions make it easy for the pump to be internally damaged.
All in all, completely flushing a pressure washer before and after each use will save many problems with dirt in the system. And just a few minutes cleaning valves will help a washer run its best.
Air in the System-
Air might even be worse for a pressure washer system than dirt. Air in the system will cause sputtering pressure at the exit end of the gun, among other things.
If air gets into the pressure pump, the pressure can cause little mini "explosions" that effectively chip away at the inside of the pump.
Air can easily be removed from the pressure washer system by "bleeding" it (see below).
Any kind of other obstruction along the path of the water should be noticeable right away due to a drop in performance. Check for grains of sand in valves, bent or kinked hoses, material in the nozzle, and excessive debris in the intake filter.
Pressure washer parts must match the rating for that washer's specs in order for it to run correctly. That includes the regulator, the unloader, the gun, and the nozzle.
Mismatching these or any other part will almost always cause performance problems right away.
A leak in a hose, a valve, around an O-ring, in the gun, or anywhere else along the water path will drop the water pressure.
Leaking hoses and guns should be replaced. If cleaning valves and O-rings does not stop leaks, they should also be replaced.
Remember how that unloader valve has an adjustable spring? Tightening or loosening this spring will set the threshold pressure at which an unloader will begin diverting water away from the pump, so adjusting the unloader spring is a roundabout way to increase or decrease the pressure of a washer.
For the most part, a professional shop should adjust an unloader, unless a user is very confident that he knows what he's doing. Some low and high pressure problems can be caused by a mis-adjusted unloader.
Unless the pressure washer is specifically a hot water model, do not run hot water through the washer. This can overwork the pump and other components very quickly.
Needs Oil Changing-
If it's a gas-powered washer, it must have its oil changed according to instructions in the user manual. This is usually about every 50 to 100 hours or operation.
Drive Belt Loose/Broken-
For gas-powered units that use a belt-drive system (instead of a direct-drive unit), the belt should be checked often and replaced as necessary.
Wearing or damage to any pressure washer part in the engine or along the flow of water should receive immediate attention. For example, a faulty regulator can either not allow enough water through to the power pump, or it can let too much through, overworking the pump.
Similarly, a malfunctioning part anywhere in the system is likely to damage other parts if the washer is operated before repairs are made.
Most worn or faulty parts have to be spotted by visual inspection and familiarity with the machine.
No matter what the symptom, diagnosing a pressure washer usually follows this order:
1. Check the power supply.
2. Check the water supply.
3. Inspect all hoses.
4. Take a look at the inlet valve.
5. Check the intake filter.
6. Inspect the nozzle.
7. Inspect the gun.
8. Check the power pump, unloader, regulator, and other valves.
Diagnosis takes this order because the things at the top of the list are more common and much easier to check. That's the good news when it comes to looking over your pressure washer. Most pressure and other performance issues will be caused by something small and simple like a clogged nozzle.
Even components like regulators and unloaders are fairly simple to replace, and can be done by confident workmen an homeowners. Once problems boil down to a power pump issue, it's usually best that the pressure washer see a shop.
Because the problems of and solutions to symptoms are so varied, we just list them below without any particular order, although we list the most common symptoms and causes first.
Lack of power to machine.
Incorrect water supply flow.
Problems in inlet area (inlet hose, inlet valve, and intake filter).
Nozzle needs cleaning or replacing.
Washer gun needs to be replaced.
Unloader valve is going out or is misadjusted.
Those are the most common causes of low pressure problems. Low pressure can also be caused by the power pump itself going out, but a faulty pump usually presents with more symptoms than just low pressure.
Nozzle is too small.
Broken pressure gauge.
Unloader valve is going out or is misadjusted.
Incorrect water supply flow.
Incorrect water supply flow.
Problems in inlet area.
Air in the system.
Pump oil low.
Dirty or obstructed valves.
There are a whole lot more symptoms, parts, and issues that we could cover, but these are the most common. Pressure washer repairs and diagnosis start getting technical once the problems reach the pump.
If the steps and guidelines provided here don't help narrow down your washer's problem, then you might be encountering a unique situation or a combination of problems. At that point, a pressure washer should go to a shop for diagnosis and repair.
Many pressure washer parts are designed to be replaced during the life of the machine, like nozzles, hoses, and guns. Even tougher components like unloaders, valves and pumps will go out over time.
But the life and performance of a pressure washer can be greatly improved by extra maintenance. Many of the problems discussed in this article can be prevented or caught early with regular checks and cleaning.
Here is a list of things to do to keep a pressure washer running strong:
Pressure washer breakdowns can be tricky, and sometimes the diagnosis leads to either a dead end or professional assistance. But the large majority of problems that washer users encounter are covered in this article and can be dealt with on the job site.
Contacting your washer's manufacturer is also a good idea if performance problems persist. If your pressure washer is in need of a repair, see our Pressure Washers page to get started finding the parts you need, or just type your washer's model number in the search field at the top of this page.