Pressure Washer Shuts Off When Trigger Is Pulled: Reasons & Solutions

Stubborn dirt on vehicles, building walls, and other concrete surfaces can prove hard to clean. Power washing comes in handy when getting rid of such dirt.

A quality pressure washer accomplishes the task effectively. Pressure washers are essential equipment used for both home and professional cleaning.

However, what happens when pressure washer shuts off when trigger is pulled? What exactly caused it, and how do you fix the problem?

This article will discuss the probable causes of pressure washer engine stalling and ways of troubleshooting. Keep reading because they are easy tasks that you can do yourself.

Pressure Washer Bogs Down When Trigger Is Pulled

pressure washer shuts off when trigger is pulled

Before finding out what makes your engine stall, you need to start by asking yourself the type of pressure washer you are using. There are four distinct types of pressure washers;

  • Hot water pressure washer most effective for cleaning oils and grease.
  • Cold-water pressure washer commonly used by homeowners.
  • Gas powered cold-water pressure washer mostly used for outdoor cleaning.
  • Electric powered cold-water pressure washer particularly used to clean surfaces that damage easily.

Pressure washer engines power differently by either electricity, petrol, diesel, or hydraulic pressure. All these are important when trying to find out how faulty your pressure washer is and how to fix it.

Troubleshooting A Pressure Washer

A stalling engine is a common problem if you own a pressure washer that needs fixing immediately. This clearly shows that there is a problem with one or two of the parts of the washer.

This now means that the faulty parts need inspection and replacement or fixing. If you have not dealt with these problems before when pressure washer loses pressure when trigger pulled, you certainly need guidelines of what to do when a pressure washer stalls under load.

Below is a list of essential tools you will need before identifying and solving pressure washer issues.

  • Wrench
  • Screwdrivers
  • Grease
  • Dry cloth
  • Alcohol
  • Pliers

You can also get a single kit containing all the tools you will need for troubleshooting. A kit has pliers, hex/Allen keys, screwdrivers, ratchets and sockets, wrenches, snips, and carry cases.

Let us start looking for the problem and probably fix here, shall we?

1) Look at the carburetor

There are two likely problems; the carburetor is either clogged or loose. A clogged carburetor needs cleaning by draining the gas tank while a loose one needs tightening.

If neither cleaning nor tightening works, you will need to replace the carburetor. A carburetor is essential for mixing air and fuel for combustion engines.

2) The unloader valve (most likely where the problem is)

Most of the pressure washer problems start and end with the unloading valve.  This part diverts the flow of water into a loop with the release of the washer trigger.

The unloader valve controls the pressure in the machine, making water come out with some level of strength.

When the pump’s pressure exceeds that of the engine, the engine starts moving and stalling. The most common issues that arise from the unloader valve are accumulated dirt in the spring, a stuck shaft, or a cracked O-ring.

With all these problems, pressure washer unloader valve adjustment and or removal becomes necessary.

3) Remove the unloader valve

Using a wrench and screwdriver, remove the unloader valve from the bay. Use the valve-retaining pin to lock the unloader valve in its bay.

Insert the screwdriver inside the retaining pin (mostly U-shaped) and pull it out to unscrew, remember to use minimum force. Both flow actuated and pressure-actuated unloaders are removed the same way.

4) Checking for issues with unloading valve

The piston, O-rings, or settings of the unloader valve might be the cause of the pressure washer shutting off. You need to check all these parts to ensure all of them are working properly to rule out their possibility of being the cause of the problem.

5) The piston

This is the major part of the unloader valve and controls pressure retention. When the pressure washer is in use, this piston moves back and forth.

If this movement stops or is interrupted, the pressure washer shuts off. You need to inspect the piston for causes of abnormal movement.

6) Adjusting the unloader valve setting

If the piston is working well, check the settings on your unloader valve. Pressure produced depends on the kind of cleaning you want or the surface/object.

The setting can be too high such that pressure washer bogs down when the trigger is pulled, which causes the problem.

You need to adjust the settings so that the valve can open and cycle the water back to the inlet to avoid pressure build-up that makes the engine stall.

Steps of adjusting the unloader valve

You need to ensure that the motor is running before you adjust pressure settings.

  • Step 1: Turn on the outlet valve. Keep it on until all the air is out, and water starts coming out.
  • Step 2: Tighten the pressure spring. Watch out for the pressure you desire.
  • Step 3: Keep moving the locknuts.
  • Step 4: Let the trigger gun go off.
  • Step 5: Place back the lock nuts, washer, and pressure spring in position.

You should now be able to get the desired cleaning pressure and solved the problem.

7) O-rings

Apart from the unloader valve, working effectively, and with perfect settings, your pressure washer can still shut down. What exactly could be the problem? 

Have you tried checking the O-rings? O-rings seal the oil pump.

With worn-out O-rings, sealing will not occur, making the unloader valve not work optimally. The only option is to buy new O-rings that will ensure no leakage from the oil pump.

Use grease to re-install or install new O-rings. Thread tape and grease cleaner will also be useful.

8) Pressure gun

Wait a minute! When did you last service the pressure gun? Maybe this is what is causing the problem.

Repairing only the unloader valve, changing settings, or even replacing O-rings and carburetors will not fix the problem if the pressure gun is in no working condition. C

onsider servicing the pressure gun or simply buy a new one.

Other Solutions That May Work

pressure washer bogs down when trigger is pulled

I have received a lot of questions from my beloved readers like why does my pressure washer keep shutting off despite the fact that I have tried all the above-mentioned solutions? 

Do not worry if you have tried all the above and nothing seems to work. Below are a few more hacks that can get the problem solved.

  • Inspect the wand screens
  • Check the water supply and fully open the water supply valve for enough water flow into the pump.
  • Use alcohol to clean the spark plug and check whether it is disconnected.
  • Take out the air filter and clean using a dry cloth. With a dirty air filter, there will be inadequate pressure regulation.
  • Release air/pressure from the system.
  • Refill oil levels if low.
  • Turn off the choke position if the engine is smoking.

If all the above does not help solve the problem with your equipment, then it is high time you considered buying a new pressure washer.

Frequently Asked Questions (FAQs)

How do you know if your unloader valve is bad?

Sudden smooth pressure loss is a clear sign of bad unloader valve. You can tell it if you notice reduced flow through the nozzle.

Why does my pressure washer keep stalling?

A clogged carburetor is main reason why the pressure washer keeps stalling. If you leave oil in the pressure washer for along period of time, it will clog the carburetor eventually.

Why does my pressure washer idle up and down?

Clogged vented fuel caps and old & degraded fuel may result in such situation. Empty the fuel tank and refill it with fresh fuel to solve the problem.

Why does my pressure washer only run with the choke on?

When there is too much air in the carb and not enough gas, the pressure washer only run with the choke on.

Why does my pressure washer keep cutting out?

When the engine is getting insufficient air due to clogged air filter, the pressure washer will keep cutting out.

Final Words

Despite purchasing the best pressure washer in the market, you can experience problems when using. Working with a problematic pressure washer can turn your cleaning hobby into a boring task.

It is crucial to ensure that you have a working cleaning device to make cleaning easier.

Like any other equipment, inspect, clean, and service your pressure washer regularly to avoid any problems. In case the pressure washer loses pressure when trigger pulled simply, put to practice all that you have learned in this guide.

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1 thought on “Pressure Washer Shuts Off When Trigger Is Pulled: Reasons & Solutions”

  1. Frist let me say thank you for the great info on this subject. I would like to see you go further and explain what is causing the needle valve to move up and down and how to check and or replace that part. I am referring to the little ball in the basket that moves up and down and comes as part of the replacement parts kit. No one says how it works or how to replace it.

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