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How to Fix Pressure Washer Soap Injector?


If you own a vehicle, a pressure washer is one of the most important pieces of equipment you need to have with you. But, sometimes, it just stops working and you end up asking the question of how to fix pressure washer soap injector?

The primary reason why your soap injector isn’t properly drawing soap is that the water pressure is too high. So, try reducing it. Secondly, clogging due to debris in your unit’s components can be another reason. You’d need to check individual components to find the one that’s causing the issue.

That was short and sweet, but you might want to go into a little depth in order to understand the root cause and effectively address it.

Let’s get started.

What is a Pressure Washer?

pressure washer wash car

A pressure washer soap injector is a piece of equipment that combines water, soap, and pressure to clean a variety of surfaces.

You can try to clean a dirty surface by throwing some water from your garden hose, but it won’t be effective. That’s especially true when the dirt has been living there for quite a while. So, most jobs require the use of soap or chemicals along with pressurized water.

The chemical is generally applied with a direct spraying system. The system isn’t a part of the pressure washer, though. It’s called the pressure washer soap injector, which I’ll talk about in a bit.

What are the Applications of a Pressure Washer?

A pressure washer can be used to clean all kinds of surfaces and impurities. The mechanical sprayer is used commercially as well as domestically and is typically used to remove:

  • Loose paint
  • Grime
  • Dust
  • Mold
  • Dirt
  • And, more!

Because it uses chemicals or soap, you can use it to effectively wash and clean persistent stains as well. This is why it’s so commonly used to clean buildings, concrete surfaces, and vehicles.

What is a Pressure Washer Soap Injector?

Pressure Washer Soap Injector

A pressure washer soap injector is an essential part of a pressure washer system. This is because it allows soap or detergent to move out of a tank into the HP hose via a pipe.

The soap is then mixed with the water creating a mixture that can remove all kinds of impurities from a variety of surfaces.

You can then point the spray gun on the surface you want to clean. The most common place you’d see a pressure washer soap injector is a car wash. Typically, these soap injectors are installed at a pump’s water outlet to let the water flow with high pressure.

What are the Parts of a Soap Injector?

A soap injector is basically a metallic component of a pressure washer system that comes with three openings:

  • Water input
  • Water output
  • Soap input

While using the soap injector, you have to make the water flow in the right direction, otherwise, it’ll not draw soap. There is an arrow indicator that tells you the right direction.

Moreover, the soap inlet opening has three components:

  1. Metal ball
  2. Rubber ring
  3. Conical spring

One of the reasons why your pressure washer soap injector won’t work is the malfunctioning of one or more of these components. Sometimes, you might even have to replace the entire soap injector.

The job of a soap injector is to pull the liquid-soap solution from a storage tank through a garden hose. Another important component of this system is the soap applicator nozzle. You attach this nozzle to the tip of the spray gun.

Its role is to allow the soap or detergent to enter the hose. Without it, when the water pressure is high, soap won’t enter the hose, making the system ineffective.

What Kind of Problems Can You Face with Your Soap Injector?

You can encounter a variety of problems while using a soap injector. And, while most of them seem similar, they’ll have different solutions.

For instance, a soap injector has a metal ball, which can get stuck, blocking the soap from getting into the hose. Another reason could be the spring breaking down. Or, maybe the rubber ring becomes too sticky.

Any one of those issues can prevent the soap from entering the HP hose. This is why we use the best soap applicator nozzle. It helps the soap get into the water hose seamlessly.

If you are looking for the right soap applicator nozzle, you might like the Tool Daily Foam Cannon. It has a ¼ inch quick connector, which makes it perfect for motorcycles, cars, driveways, and other applications.

Should You Use Dish Washer in a Pressure Washer?

Yes, you can use a dishwasher in your pressure washer, but make sure to dilute it with some water. This is important to make sure that your pressure washer doesn’t get clogged.

However, keep in mind that a diluted soap wouldn’t be as effective as a commercial detergent. But, it could be a good option if you are looking for a more cost-effective option.

Can You Use Vinegar to Clean a Pressure Washer?

Yes, you can safely and effectively use vinegar in your pressure washer. Vinegar is a powerful cleaner and can work for mildew, debris, and dirt.

Best Detergent to Use in a Pressure Washer Soap Injector

You can find a variety of detergents for your pressure washer. Choosing the right detergent might not be as simple though. If you are looking to buy one for your pressure washer, you might like this one on Amazon.

Can You Use Pressure Washer Without Soap?

Although you can use a pressure washer with just water, soap is necessary to effectively clean a surface. A strong jet of water might make a surface look clean, but it won’t effectively remove germs and impurities.

How to Fix a Pressure Washer Soap Injector?

One of the most common reasons for a soap injector not working is the high-pressure build-up in the soap injector nozzle. But, there can be more! In the next section, we’ll provide you with step-by-step instructions to help you fix your soap injector.

Working Principle of a Soap Injector

To address any piece of equipment effectively, you need to understand how it works. So, before we dive into the possible solutions, let’s talk about how a soap injector works.

A soap injector is a simple device that constricts a water stream so that soap is drawn from a container to the outlet through suction. When water flows in the form of a narrow stream, its velocity is increased. This decreases the pressure, ultimately pulling the soap towards the vacuum.  

Moreover, there is a valve that controls the ejection of soap or chemicals from the injector. The valve limits the liquid flow back towards the soap bucket if the flowing water’s pressure gets high.

Assuming that you know how a soap injector works, it’s now easier for you to understand potential problems that prevent it from working properly.

If all that sounds too technical or confusing, don’t worry. It’s not that important. The important thing is to get your problem fixed, which is what we’ll talk about now.

Fixing a Pressure Washer Soap Injector

If your soap injector isn’t working, it’s probably because the pressure of the water stream is too high. As a result, there is no chemical suction.

One of the first things you need to check is your nozzle type. Is it a high-pressure nozzle or a low-pressure one? If it’s a high-pressure nozzle, you might want to consult the user manual and check the recommended nozzle type.

High-pressure nozzles are generally not suitable for chemical injectors. So, switch to a low-pressure nozzle and see if the problem still persists.

Check for Blockages

Another common soap injector problem is the blockage of the valve or nozzle area. You might be facing this issue as a result of the buildup of debris in the injector tube. As a result, the chemical isn’t drawn to the outlet.

The solution to this conundrum is obvious; plug out the debris from the affected area. Check the tube, valve, and nozzle and see which one of those is clogged or affected.

You might also want to use a chemical filter on the tube to prevent blockage in the future. The chemical filter will keep the debris out, keeping the tube free of any foreign particles.

While those were the two most common reasons for a soap injector not working, there can be more.

Worn Out Components

Clogging and blockage can also occur as a result of the wearing out of individual components. So, to pinpoint the problematic part, you’ll have to do some troubleshooting.

What you can do is, see if the chemical kit is working properly. You can do that by removing the hose from the pump. Remove the components one by one and see if the detergent fluid comes out.

Keep the engine on while removing individual components. Removing the problematic component will siphon out the detergent fluid.

High Inlet Pressure

A chemical injector can’t work effectively when the inlet water pressure is too high. But, why would water flow with such a velocity that it prevents the flow of soap?

It can be because you are using a high-pressure nozzle, as discussed before. Or, it can be because the pressure of the water supply source is too high.

We’ve talked about the solution to the first issue. For the second one, what you can do is, adjust the valve in order to vary the water pressure. Keep adjusting it until it starts drawing the detergent.

Fix the Chemical Viscosity

Too high a chemical viscosity can impact the draw rate of the injector negatively. See, the higher the viscosity of a fluid, the thicker it is. The viscosity of a chemical increases when you keep it in an open container.

You’d need to thin some thick chemicals before using them in your injector. Generally, chemicals that have a viscosity closer to water work best.

That said, if you think your pressure washer soap injector isn’t fixable, you can always get a new one. Considering switching to a new one? You might want to look at this one on Amazon.

How To Use a Pressure Washer Soap Injector?

Fluid inspection

Doesn’t matter if your soap injector is external or internal, the first thing you want to do before using it is fluid inspection.

Ensure proper pressure

Make sure that the water pressure is right and there are no leaks.

Inspect the detergent hose

Next, inspect the detergent hose for any debris and make sure it’s not clogged.

Check soap solution

Then, you want to check the solution ratio. Generally, it should be 1/3rd soap and 2/3rd water. That would be enough for any type of application.

Install soap nozzle

Just place the hose into the chemical solution and install the soap nozzle. Without it, your soap injector won’t work. You can now start the unit and wash your vehicle.

Downstream Chemical Injector Working

A downstream chemical injector uses the Venturi effect. What this means is that it pushes the water in a constricted section of the injector. This increases the velocity of the water, creating a vacuum and drawing the chemical solution in.

The small orifice size generates a vacuum by reducing the water pressure. A major reason why a soap injector stops working is the absence of this vacuum.

Pressure Hose Length

The longer the water contacts with the inner tube of a hose, the more backpressure is generally generated. A longer hose would mean more friction, which leads to greater backpressure.

High backpressure of water negatively impacts the venturi effect. The shorter your hose is, the lower the backpressure, and the higher will be the chemical draw.

Therefore, when a high chemical draw is needed, a shorter hose is ideal. The important thing is to keep in mind that the length of the hose will determine how much soap is drawn to the outlet.

Can You Use Bleach with a Pressure Washer?

Bleach can be very effective at killing and removing mildew and mold. However, you should never use it in a pressure washer.

Damages pump’s seal

The use of bleach in a pressure washer can lead to water and oil leakages because it damages your pump’s seal. This makes your unit ineffective and can add to the maintenance costs.


Bleach isn’t an environmental-friendly chemical and its use is detrimental to humans, plants, and animals.

Scrub not spray

If you want to use bleach to clean a surface, don’t spray it. Instead, scrub it on that surface and leave it for a while. You won’t be releasing the chemicals in the air that way.

What Chemicals Do Soap Injectors Use?

The type of chemicals a soap injector uses depends on its end-use. They are different for commercial and domestic applications. Eventually, it depends on the type of impurities you want to remove from a surface.

Here are a few examples:

  • Oxalic Acid– Used for rust removal
  • Citric Acid – Handy for cleaning driveways
  • Sodium Hydroxide – Typically applied on glass and steel
  • Ammonia – Great for stainless steel
  • Sodium Hypochlorite – Used for stain removal

Do’s and Don’t of Pressure Washing

The first thing you want to do after properly setting up your unit is to make sure there is an adequate water supply. See if it can fill a 5-gallon bucket within a couple of minutes.

If it takes longer than that, it indicates that the pressure is not enough to run the washer effectively.

In addition, you don’t want to underestimate the pressure of the water jet. See, it’s designed to clean the toughest of stains, and can even cut through human skin, so you need to be a little careful while using it.

Frequently Asked Questions

Why Is My Pressure Washer Soap Injector Not Working

Generally, a pressure washer soap injector stops working because the backpressure of the water is too much to pull the soap. Another reason could be the blockage of a component. In the second case, you’d have to perform troubleshooting to get to the root of the problem.

Why Does My Pressure Washer Won’t suction Soap

As already discussed, the most common causes of this are:

  1. Water pressure too high
  2. Internal blockages

Why is My Pressure Washer Not Siphoning Detergent?

Let’s address this question from a technical angle.

Your soap injector’s nozzle’s size plays a big role. When you operate your unit with a high-pressure nozzle with a small hole, no chemical would enter the water stream. When the pressure is reduced, the ball inside the injector gets lifted, allowing the soap to flow out.

Why Won’t Your Pressure Washer Pull Soap?

The most common reason why your pressure washer won’t pull soap is that the water pressure is too high. When the pressure is too high, the unit won’t be able to suck soap from the bucket.

Final Thoughts

This was all about how to fix a soap injector in pressure washer. There can be multiple reasons why your pressure washer soap injector isn’t working properly.  

Primarily, it’s the excessive pressure of the water that’s causing the problem. What you can do is adjust the valve or reduce the pressure at the source.

The second is your unit’s components getting clogged. To solve this one, you’d have to do some troubleshooting and find the problematic component.

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