Why Your Pressure Washer Soap Injector Is Not Working

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Air pollution. Car exhaust. Bird droppings. Wind and rain depositing dirt or mud. Mold and mildew. There are a lot of reasons why the exterior of your home can start looking dirty, especially in the bright sunshine of summer. This is why it’s always a good idea to power wash the outside of your house at least once a year; it’s the kind of annual maintenance that’s required to keep the home’s exterior looking as good as the landscaping that surrounds your home. Professionals and do-it-yourselfers alike rely on pressure washers to get this job done, but the job will only be done right if the equipment is functioning properly. While correct water pressure is a necessity, it’s also important that soap is mixed with the water to do a thorough cleaning. If you’ve discovered that your pressure washer’s soap injector is not working, Repair Clinic has two likely causes you should troubleshoot. First, let’s take a look at how a pressure washer pump operates and how the soap is introduced to the water supply. 

How a pressure washer pump operates

Both electric-powered pressure washers and gas-powered pressure washers have two main components: a power source and a water pump.

Know your pressure washer’s power source and water pump style

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 pump pistons operate like engine pistons

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.

How soap is introduced to the water supply

How is the soap introduced to the water supply? On some pressure washer models, the output pipe will have a chemical injection port. This port is what introduces the soap or detergent solution to the water stream. Once the water and soap reach the spray gun, it’s all under the control of the user. When the spray gun trigger is depressed, the pressurized water, now mixed with the detergent solution if applicable to the pressure washer model, 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.

Two causes of a pressure washer soap injector not working

If you’re noticing that soap does not appear to be mixing properly with the water spraying out of the spray gun or wand, here are the two potential causes you should consider:

  1. Improper sprayer nozzle – For the soap injector to work properly, a low-pressure nozzle must be used to draw the detergent solution into the hose and output pipe. Check to see if the nozzle you’re using is the correct one. A nozzle with a smaller hole will provide higher pressure than one with a larger hole, so if the hole in the nozzle is too small, the soap will not be drawn into the water stream properly. Refer to your pressure washer owner’s manual to determine the proper size nozzle for your application.
  2. Defective soap injector components – Various soap injector components such as the injector piston, O-rings, or spring could be defective, preventing the detergent solution from properly mixing with the water jetting out of the spray gun or wand nozzle. You can purchase a chemical injection kit that contains all of these components so you can replace one or more of them to solve the problem of the soap injector not working.
Pressure Washer Soap Injector Not Working?

Repair Clinic has genuine OEM parts to fix your pressure washer fast

A successful pressure washer repair starts with finding the right part that works with the equipment your fixing. Whether you’re looking for a replacement pump, nozzle, spray gun, or hose, you should use the genuine original equipment manufacturer (OEM) part for the best results. This is why Repair Clinic stocks only genuine OEM replacement parts for pressure washers manufactured by Briggs and Stratton, Portland, Homelite, Honda, Husky, Kohler, Troy-bilt, and more. What’s the quickest way to locate the part you need? Enter the full model number of the pressure washer, or the pressure washer’s engine if you have to replace a gas-powered engine part, in the Repair Clinic website search bar. Next, find the correct category for the part you want using the “Part Category” navigation filter (example: “Hose, Tube & Fitting”) followed by the appropriate name of the part using the “Part Title” filter (example: “Nozzle”). The resulting part will be the exact match for the pressure washer you’re trying to fix.

Repair Clinic has the repair help you’re looking for

So, you’ve now got the right part for the job, but how do you install it correctly? When it comes to fixing a pressure washer, Repair Clinic has the repair help you’re looking for. Visit the Repair Clinic website’s “Videos & Articles” section for equipment schematics, troubleshooting tips, and videos, such as one showing how to replace a chemical injector on a Homelite pressure washer (Model UT80993B) or one providing a step-by-step procedure for installing a new spray wand nozzle on the same model.

But the education doesn’t stop there. As your repair partner, Repair Clinic has thousands of videos, schematics, tips, and articles covering all major home appliances, lawn and garden equipment, and heating and cooling systems.

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