A hot summer day is a perfect time to power wash your home’s siding, deck, or driveway when that cool mist deflecting back at you can actually provide some relief from the heat. But the “power” in that power wash is dependent on your pressure washer having sufficient water pressure. Are you only getting a weak stream when you squeeze the trigger on the pressure washer’s spray gun? Then you’re lacking the power you need to get the job done right. Let’s examine how pressure washers create that water pressure and address the two likely reasons why your equipment may not get the pressure you need.
How pressure washers create pressure
While air can be compressed, liquids cannot. When you apply pressure to liquid, it will push outward in every direction equally. This principle is what allows pressure washers to create a high-pressure stream of water that, when combined with detergent, can effectively clean dirt build-up on surfaces exposed to the elements.
Both electric-powered pressure washers and gas-powered pressure washers have two main components: a power source and a water pump. For electric-powered pressure washers, that power source is an electric motor whereas the power source on most gas-powered models will be a 4-cycle engine. The water pump can be an axial pump or a triplex pump. Although these two kinds of pumps can look dissimilar, both use three plungers or pistons to regulate the water.
The three plungers or pistons in the pump operate in a similar manner to a piston in an engine. As each plunger or piston travels upward, it draws water from an attached garden hose through an input check valve. As the plunger or piston travels downward, the water is forced through an output check valve. The water then flows through an unloader and output pipe on the pump, and then through a hose to the spray gun. When the spray gun trigger is depressed, the pressurized water will exit through the trigger handle assembly itself or through a separate spray wand and nozzle. When the trigger is released, the high-pressure water stream should stop. The unloader will then detect the increase in pressure and a spring-loaded valve will open a passage in the pump so the water can circulate back to the inlet pipe. This feature allows the engine to run while the pressure washer is not in use.
So what determines the pressure in a pressure washer? It all comes down to the power source. The higher the motor or engine speed, the more pressure the pump can create. Many electric-powered pressure washers provide between 1,300 and 1,700 pounds per square inch (psi) of pressure (although some electric models can provide pressure as high as 3,000 psi) whereas gas-powered washers will consistently provide between 2,000 and 3,200 psi of pressure. The higher the water pressure, the more efficient the equipment will be at power washing.
Why is there no water pressure in my pressure washer?
If your pressure washer is not providing sufficient water pressure, you should confirm the equipment’s motor or engine is functioning normally. A poorly-maintained engine, such as one that stalls unexpectedly, may not be able to provide enough pressure to the pump for the equipment to work optimally. Provided the motor or engine is running efficiently, there are really only two likely causes for why the pressure washer would have little or no water pressure:
- Insufficient water supply – No matter how well the pressure washer motor or engine is functioning, if the water supply coming to the equipment is insufficient, water pressure within the pressure washer will be significantly compromised. While pressure washers can deliver between 1,300 and 3,200 psi of pressure, they only require about 20 psi of water pressure to enter the equipment through that garden hose to operate properly. Since most home spigots will provide approximately 30 psi to 40 psi of water pressure, this would not normally be a problem. What can cause a problem is the length of the hose connecting the spigot to the pressure washer. Water pressure is reduced as it travels through the hose, so using a very long hose, or multiple hoses connected together could result in insufficient water pressure reaching the washer’s input check valve.
- Malfunctioning pump – If you’ve determined there is an appropriately-strong water supply reaching the equipment, then it’s likely the pump is malfunctioning. You should always purge the air from the pump before operating the pressure washer. As noted above, air can be compressed, and when excess air is trapped within the pump, the check valves, plungers, and unloaders can become damaged which can result in pressure loss. To solve this problem, you will need to replace the pump or one or more of its various components. Some pressure washer models will require you to replace the pump as a complete assembly, while other models will allow check valves, O-rings, and plungers to be replaced separately. Be aware that most triplex pumps require oil to be added and changed periodically to keep the pump in good condition, so follow the manufacturer’s recommendations. It is also recommended you use a product like Pump Saver to help protect the pistons and seals when the pressure washer is not in use.
Finding the right pressure washing pump parts, such as check valves, plungers, or O-rings, is critical to successfully repair your pressure washer. To get started, enter the full model number of the pressure washer, or the pressure washer’s engine, in the Repair Clinic.com search bar to see a full list of compatible parts. Repair Clinic stocks genuine OEM parts for all the top brand pressure washers, including Briggs and Stratton, Portland, Honda, Husky, Kohler, and Troy-bilt models, and by using the part category and part title filters, you can easily identify the specific part that works with your model.
As your repair partner, Repair Clinic offers you more than just the right part shipped to you quickly. The website’s free “Repair Help” content library is filled with thousands of videos, articles, diagrams, and step-by-step instructions to take you through the entire troubleshooting and repair process for all of your outdoor power equipment, home appliances, and heating and cooling products.