Pressure Washer Shuts Off When Trigger Is Pulled (We Have a Fix)

Upgraded Home Team
by Upgraded Home Team

A pressure washer can be a highly useful tool for a variety of projects around the house. You can use it to keep your patio clean or get nasty stains off of the concrete, plus many other different projects. But just like anything else, it can break down and stop working from time to time, and an annoying issue is when the pressure washer shuts off when the trigger is pulled.

If your pressure washer shuts off when the trigger is pulled, it’s likely a faulty unloader valve or the unloader valve’s settings are incorrect. The valve can have deteriorating O-rings, a loose spring, a faulty trigger, or issues with the piston movement. Repair the valve or replace it if this is the case; otherwise, it could be a clogged or loose carburetor, dirty filter or spark plug, or damaged wand screens.

So, now that we have identified the potential problems, it is time to take a closer look at how to fix them. Since the most common reason for this problem is a faulty unloader valve, it’s essential to understand how the unloader works and how to fix it.

Pressure Washer Shuts Off When Trigger Is Pulled — Understanding The Unloader Valve

The unloader valve is meant to divert flowing water from the pump to the inlet side. This causes water to flow in what is known as a loop back to the pump with almost no pressure. This is instead of going to the nozzle under normal operating pressure.

Flow can be directed to a float tank, to the pump inlet in your washer, or into another type of reservoir. Without it, pressure will not be able to flow to your nozzle, and you won’t have much use out of the pressure washer as a whole.

With most types of pressure cleaning equipment, the pump motor generally gets turned on and off on the machine itself. The problem with this is that you can be several feet away using the hose, and it can be a pain to have to walk back to the machine just to turn it off.

This is where the handle comes into play. Using the trigger (and the unloader), you can turn the pressure and flow off and on whenever you want. Essentially, they direct the flow of the water based on your direction (squeezing the trigger).

More Reasons Pressure Washer Shuts Off When You Pull The Trigger

Yes, the root cause of your pressure washer woes is the unloader valve, but the issue can get more specific. Within the unloader valve or many parts, each of which can go bad and cause your pressure washer to shut off when you pull the trigger.

Here is a quick overview of those parts before we discuss how to fix the problem.

  • Piston — The piston is one of the most significant parts of the unloader valve as it controls pressure retention. If anything blocks the piston’s movement, the pressure washer will shut off. Therefore, if there is anything in the way, like debris or dirt, it can hinder the piston’s performance.
  • O-Rings — O-rings create a seal between different parts of an appliance. If they wear down, oil can leak from the pump, causing problems with the unloader valve.
  • Pressure Settings — You can adjust the settings of your pressure washer, and if they are too high, the unloader valve won’t be able to do its job.
  • Trigger — This is what you use to start your pressure washer. If it doesn’t work, it won’t create the chain reaction necessary for the unloader valve and everything else to do what they need to do.

How To Fix When A Pressure Washer Shuts Off When Trigger Is Pulled

So, if you’ve determined the unloader is behind the issue, how do you correct the problem? First, you need to have the proper tools on hand to get the job done. You’ll need a screwdriver, a wrench, some kerosene or alcohol, and some grease.

If you don’t have these tools readily available, you can purchase them at a local hardware store without much of a problem.

Step 1: Unplug And Remove The Unloader Valve

The first step is to grab your screwdriver and wrench to unplug your unloader valve from the bay that it is located in. Unplug the retaining pin that locks your unloader valve into the bay. For the most part, manufacturers will keep the valve visible so that it can be easily changed.

Locating the pin should be easy, even on some of the most powerful pressure washers out there. The pin is in the shape of a U, which is common for just about any type of pressure washer. Then, insert the screwdriver inside to pry out the retaining pin.

After you have successfully removed the retaining pin, it is time to get the unloader valve out of its bay. You need your screwdriver and a gentle pull to get this done. One of the major pieces to the unloader valve is the piston. This controls pressure retention in your pressure washer.

The piston in the pressure retention system will move backward and forward when the pressure washer is running. Should the piston not move easily and freely, the pressure washer will wind up shutting off. Check to make sure that the piston is moving freely. If it has issues moving, this is likely the culprit.

Step 2: Replacing The Piston

If the piston is working fine, this step won’t be necessary. But should there be issues with the piston, you will need to remedy the situation. Take the piston out from the valve. You can use the wrench to loosen the nut that holds the piston in with the valve.

From here, unplug both the spring and the piston. Make sure to clean both thoroughly with either kerosene or alcohol. When you have cleaned and dried them, use some grease – silicone grease – on both and then set them back into place. This should let the piston and spring work smoothly, the way they were meant to be.

Step 3: Check The Unloader Valve’s Settings

There are settings in the pressure washer that allow the unloader valve to produce the requisite amount of pressure needed to do a job. Check those settings to make sure that they are where they need to be. If the setting is too high on the unloader valve, it could stack the engine and make the washer not work.

The unloader valve has to remain open in order to cycle the water back over to the inlet side properly. When that valve doesn’t open up, high pressure builds up that can stall out the engine. Check your settings to make sure that your unloader valve isn’t facing improper pressure levels.

Step 4: Check The O-Rings

One of the more common issues when it comes to pressure washers shutting off has to do with the O-ring. The unloader valve has O-rings in it that are also known as seals or washers. When those O-rings get worn down, deteriorate, or are torn out, they can’t seal the pump. That means that your unloader pump will fail, too.

Check the O-rings to see if there is any major wear and tear or deterioration. If it isn’t okay to be put back into the unloader valve, replace it immediately. Get the exact same size as the old one to avoid further issues. The oil pump should be properly seated when replaced with a new O-ring.

Step 5: Check Out The Pressure Washer’s Trigger

Sometimes, the trigger can be the culprit in instances like this. Inspect your trigger to make sure that it is working at a functional level. You can adjust the uploader valve all you want, but if the trigger isn’t working properly, it won’t matter.

Check out the trigger when you adjust the pressure unloader valve. You may need to replace the trigger entirely in some cases.

Other Potential Reasons Your Pressure Washer Shuts Off When Trigger Is Pulled

If you have tried all of the above steps and still have issues with your pressure washer, there are a few other possible alternatives. Check the air filter; clean it out if it looks dirtier than normal. Clean the spark plug on the machine using alcohol.

The carburetor could also be clogged or loose. Tighten it if it’s loose. If it’s dirty, drain the gas tank and then clean the carburetor to see if it solves your problem.

Sometimes the water inlet or the wand screens can be the issue. Check those to make sure they are in good condition as well. If everything else fails, try buying a new unloader valve or taking it to a local expert.

Keep in mind a new unloader valve can cost anywhere from about $45 to $100, depending on what you need for your pressure washer. So, carefully weigh your options against the age and value of your pressure washer. If you purchase a new valve, make sure to do so from a certified dealer, so you get a quality product.

Your pressure washer can be a highly effective tool to have for chores around the yard. Provide routine maintenance to ensure that everything remains working in an orderly fashion. Allowing parts to get dirty or worn down means that the unit will not work the way that it is intended. If deterioration gets to be too bad, it can be time to buy a brand-new machine.

Maintenance Tips For Your Pressure Washer

Of course, one of the best ways to keep your pressure washer operating efficiently is to maintain it well. Here are a few tips to help keep your pressure washer in tip-top shape.

  • Refer to your pressure washer’s manual for any specific maintenance routines and instructions.
  • If you’re using the pressure washer on a hot day, allow it to cool off before starting a new project. Let it sit for about 30 minutes, so it doesn’t get overheated.
  • Check the oil and fuel levels every time you turn on your pressure washer. Even if you have just filled the tank, check the levels. Doing this every time can help you identify any potential leaks quickly.
  • Check the debris screens and detergent system before using your pressure washer and clean them if dirty. If they are damaged, replace them,
  • Inspect the hoses and spray gun before using your pressure washer to make sure there are no leaks, tears, or cracks. If anything is damaged, replace it.
  • Before connecting the pressure washer to your garden hose, run water through the hose to flush it out.
  • After using the pressure washer, drain excess water, relieve pressure in the system, and clean out the detergent system.
  • Regularly change the oil and filters (or clean the filter as recommended).
  • Only use gas that is 30 days old or less.
  • Tighten and lubricate connections regularly.

Regularly inspecting your pressure washer can alert you to potential problems while they are still minor. You can fix them right away to avoid larger issues forming and damaging your pressure washer.

Related Questions

How much is a new pressure washer?

Pressure washers vary in price based on size and type. On average, a gas-powered pressure washer costs about $379, an electric model about $167, and a battery-operated model about $182. Also, the greater the psi, the higher the price tag since the pressure washer will have more cleaning power.If you’re not ready to purchase a new pressure washer, many home improvement stores, like Lowe’s and Home Depot rent them. You can rent a gas pressure washer that can handle medium-duty projects for about $80 a day or $320 a week.If you just have a few small projects to do, you could rent an electric pressure washer for about $27 for four hours, $39 for one day, or $156 for the week. If you’re planning a long project, you can also rent a pressure washer for a month for about $468 or $960, depending on if it’s electric or gas.

What if my pressure washer stalls when the trigger is pulled?

If your pressure washer stalls when you pull the trigger, you’ll need to check many of the same things you would check if it shuts off completely. Once again, the most common culprit is the unloader valve. Therefore, unplug and remove it so you can inspect it thoroughly.Check the piston, O-rings, valve settings and adjust as necessary before reinstalling the valve. If the situation doesn’t improve, you may need a new unloader valve.If your pressure washer stalls often, it could also be a clogged carburetor. You can help prevent this issue by avoiding leaving oil in your pressure washer for extended periods.

How much does it cost for professional pressure washer repair?

Having a professional repair, your pressure washer can cost around $200 to $300, depending on the specific issue. Therefore, it’s important to consider how much you paid for the pressure washer, how old it is, and how much life it has left before paying for a repair. For many residential pressure washers, it might make more sense to buy a new one instead of paying to fix it professionally.If you’re leaning toward replacing your pressure washer and consider yourself fairly handy, you could always attempt a DIY fix first. This will cost you significantly less, and you could save yourself some money.But, if your repair fails, you’ll be out the cost of the part on top of having to buy a new pressure washer. However, you could always potentially sell the part at a reduced rate to try and get back some of your money.

Upgraded Home Team
Upgraded Home Team

We are a team of passionate homeowners, home improvement pros, and DIY enthusiasts who enjoy sharing home improvement, housekeeping, decorating, and more with other homeowners! Whether you're looking for a step-by-step guide on fixing an appliance or the cost of installing a fence, we've here to help.

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