Why the pressure washer shuts off when you pull the trigger

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If you have a pressure washer, you must have come across a troublesome situation where your pressure washer shuts off when the trigger releases. It mostly happens because the unloader valve has some problems. There are some issues with the unloader valve that stalls the pressure washer engine pump.

Troubleshooting and fixing this problem is an easy process. If you have such a problem with your pressure washer, read the article carefully and follow the steps. This article will teach you how to fix your pressure washer that shuts off when you pull the trigger.


In the following procedure, you will require some equipment; you must have a

  • A Screwdriver
  • A wrench
  • Alcohol
  • Grease

Step 1:

Firstly, you need to unplug the unloader valve using a wrench and a screwdriver. You can do that by opening the pin that retains the valve and locks the unloader with its bay. Almost all the pressure washers have a visible unloader valve. A retaining pin is a U-shaped pin and its common in every pressure washer. You need to insert your screwdriver into the retaining pin, pull it upwards and unscrew it.

Step 2:

Once you have unscrewed the retaining pin, use a screwdriver to pull the unloader valve from its bay gently. The unloader valve’s piston is one of the most vital components. It more back and forth when you run the pressure washer.

If the piston stops moving or can’t move freely, it causes the pressure washer to shut off. Check the piston and make sure it moves freely; if not, you will have to fix or replace the piston. Once you have set the piston in its place, test runs your pressure washer and check if the problem is solved.

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Step 3:

In case the piston is not moving freely, you will have to repair it. Unplug the piston and spring from the unloader valve by unscrewing the nuts that hold the piston with the valve. Thoroughly clean the piston and the spring with alcohol or kerosene.

After the piston and the spring are perfectly cleaned, grease them using silicon grease. Fix the piston and the spring in place and runs your pressure washer. If this procedure fixes the problem, enjoy using your pressure washer; if not, move onto the next step.

Step 4:

The unloader valve has settings for adjusting water pressure. When you pull the trigger, too high water pressure setting can stack up the engine, resulting in shutting off the pressure washer. Usually, the unloader valve opens up to cycle the water back to the water inlets.

If the valve doesn’t open up, it builds high water pressure that stalls the engine. To fix this issue, you need to set your unloader valve setting accordingly. After that, run your pressure washer to check if the problem is solved.

Step 5:

The unloader valve has O-rings, generally known as seals. If the O-rings are in poor shape and are not enough to seal the oil pump, it may cause the unloader valve to stop working. As a result, your pressure washer will shut off immediately. Check the O-rings, make sure they are in fine shape if they are in poor condition, and replace them with new compatible O-rings.

When the oil pump is sealed correctly, the unloader valve will start working. Test run your pressure washer check if the problem is solved.

Step 6:

Another thing that can cause your pressure washer to shut off is a faulty pressure washer spray gun. Check the spray gun; if it is in good shape and working correctly, then you don’t need to do anything with it. If the spray gun is in poor condition and is not working correctly, you will have to buy the best pressure washer spray gun.

Step 7:

Besides the mechanism as mentioned above, you can also check your pressure washer’s

  • Air filter

If the air filter is not working, replace it with the best air filter for pressure washers.

  • Spark plug

Sometimes the spark plug gets rusty, and due to other reasons, and stops working, try cleaning it with alcohol.

  • Water inlet

You should also inspected the water inlet. It may have rusted or had some residue inside; you should clean it. If it is damaged, you should buy the best pressure washer hose.

  • Extension wand

Faulty extension wand screens can also cause the pressure washer to stop working. Inspect the extension wand. If it is not working, replace it with a new pressure washer extension want.


Pressure washers are one of the most convenient and powerful machines. If you maintain and take care of your pressure washer, it will work effectively for a lifetime. If you ever come across a problem where your pressure washer shuts off when the trigger is released, you need to follow the steps mentioned earlier.

If the problem is still not solved, we would recommend you to take your pressure washer to the nearest pressure washer expert as soon as possible. You can also buy the best pressure washers under $200 as well.

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