Pressure Washer Dies When I Pull the Trigger: Helpful Tips


A pressure washer is a valuable piece of equipment that helps remove stubborn dirt and on many surfaces outside the house or on your car. Cleaning dirty surfaces effectively with a pressure washer is a satisfying job until the pressure washer stops working. One of the more common problems is that the pressure washer stalls when the trigger is pulled.

Pressure Washer Dies When I Pull the Trigger:

In general, a pressure washer shutting off when the trigger is pulled indicates a faulty unloader valve. An unloader valve is one of the most critical parts of the pressure washer. Hindrances in the piston movement, deteriorated O-rings, loose spring, inappropriate setting of the unloader valve, and faulty pressure washer trigger can cause the pressure washer to shut off when it is pulled.

Pressure Washer Dies When I Pull the Trigger: Helpful Tips 1

This article will provide you with information about the different causes of the pressure washer stalling when the trigger is pulled or released. I will also show how to diagnose and repair the unloader valve.

Why Does My Pressure Washer Die When I Pull the Trigger?

A pressure washer stalling when the trigger is pulled is mostly due to a faulty unloader valve, O-rings, pressure washer trigger, or a too-high setting of the unloader valve.

The root cause of a stalling issue is usually a problematic unloader valve. The unloader valve cycles the water back to the inlet, diverting the flowing through the pump system. The unloader valve redirects the water into a loop when the trigger is released. This helps to retain the water pressure even when it’s discharged through the nozzle.

Here are some common problems that cause the pressure washer to stall when the trigger is pulled.

● Faulty unloader valve:

Most pressure washer problems start and end with the unloader valve. The unloader valve controls the pressure and allows the water to come out of the nozzle with high strength. It diverts the flow of water into a loop to retain high pressure when the trigger is released. When the pressure in the pump exceeds the engine pressure, the engine shuts off. The most common problems in the unloader valve are cracked O-rings, accumulated dirt in the spring, or a stuck shaft.

● Problem with the piston:

The piston controls pressure retention and is one of the most important parts of the unloader valve. The piston moves back and forth when the pressure washer is operating. When this back and forth movement is stopped or interrupted, the pressure washer shuts off. To inspect the piston, remove it from the unloader valve.

● Worn out O-rings:

Faulty and deteriorated O-rings cause leakage from the oil pump, which doesn’t allow the unloader valve to work correctly. As a result, the pressure washer shuts off when the trigger is pulled. You must check the O-rings of the unloader valve and replace them if they are cracked.

●Poor pressure setting of the unloader valve:

High-pressure settings inhibit the engine’s ability when the trigger is released. This is because, at higher settings, the unloader valve doesn’t allow the water to divert in the loop to the inlet to release pressure. This builds up the pressure in the machine and causes the pressure washer to stall. You must adjust the settings so that the unloader valve can divert the water back to the inlet to avoid pressure build-up that causes the pressure washer to shut off.

● Problem with the pressure washer trigger:

Fixing all the problems discussed above may not fix the pressure washer die when the trigger is pulled. The trigger may have an issue. First, try another trigger to see if this is indeed the problem. If so, disassemble the trigger and see if you can find a problem with it. Replace it if you can not fix it.

How to Fix A Pressure Washer That Shuts Off When the Trigger is Pulled

To fix a pressure washer shut-off problem, you need to follow some simple steps. Disassemble the unloader valve. Carefully inspect the piston, O-rings, and spring. Adjust the pressure settings of the unloader valve. If the issue isn’t resolved after following all these steps, you must always check the correct working of the pressure washer trigger.

As discussed in the previous section, a faulty unloader valve usually causes a pressure washer to shut off when the trigger is pulled. The unloader valve diverts the water back to the inlet to retain the pressure. When the unloader valve doesn’t work correctly, it stacks the pressure inside the machine when the trigger is released. Pressure builds up inside the pressure washer and causes it to shut off when the unloader valve fails to open.

Here are the steps that will help you to fix the problem:

● Step 1: Inspect the unloader valve

The first step is to inspect the unloader valve. A pressure washer shuts off when the pressure inside the pump increases higher than the engine pressure. Inspect the unloader valve to check for the dirt around the spring, stuck shaft, or worn-out O-rings. You need to disassemble the unloader valve for a thorough inspection.

● Step 2: Remove the unloader valve

You need a wrench and a screwdriver to remove the unloader valve. Remove the retaining pin that keeps the unloader valve in place. Release the pin by unscrewing it and placing the screwdriver inside the pin, and pulling it upwards to remove it. This allows you to remove the unloader valve easily. Don’t use excessive force when removing the unloader valve to avoid damage.

● Step 3: Check the unloader valve

Check the different parts of the unloader valve, such as the piston, O-rings, and the spring, to ensure they are in good working condition.

●Step 4: Inspect the piston

The piston is a vital part of the unloader valve. If the movement of the piston stops or is interrupted, the washer may shut off when the trigger is pulled. If the piston isn’t in good working condition, replace it.

● Step 5: Check the O-rings

O-rings seal the oil pump and ensure that there is no leakage. Unfortunately, these rings get worn out over time. Cracked O-rings can’t seal the oil pump properly, which hinders the working of the unloader valve. To avoid leakage, you must replace the cracked O-rings. You can use grease and thread tape to install the new O-rings properly.

● Step 6: Adjust the unloader valve settings

The unloader valve doesn’t properly divert the water back to the inlet to release pressure at very high settings. This builds up pressure inside the machine, which causes the washer to shut off when the trigger is pulled. You must adjust the settings so that the unloader valve can open and divert the water in the loop back to the inlet to release pressure.

Make sure that the engine is running before you adjust the unloader valve’s settings. To release the air out of the washer, turn on the outlet valve. Tighten the unloader valve spring to achieve the desired pressure. Next, move the lock nuts while adjusting the pressure. Once the desired pressure is adjusted, release the trigger and place the lock nuts, spring and washer back in position.

● Step 7: Inspect the pressure washer trigger

A pressure washer trigger requires regular servicing to work effectively. Remember that fixing all the problems discussed above may not help you to fully solve the problem if your pressure washer trigger isn’t working properly. So, it’s recommended to check and service it. If you are unsure if it works correctly, try to use a replacement and see if that fixes the problem. Replace when needed.

● Step 8: Other potential solutions to fix your pressure washer dying when the trigger is pulled

If all the fixes discussed above doesn’t solve your problem, you may want to try the following:

  • Check the wand screens.
  • Try to release the air or pressure from the washer.
  • Gas pressure washer: Check the spark plugs and clean them with alcohol.
  • To regulate pressure, clean the air filter and remove any dirt clogged in it.
  • Ensure that the water supply is providing enough water flow into the pump.
  • Check the oil level and refill the oil if it’s low.

Pressure Washer Stalls When the Trigger is Released: How to Solve It

A pressure washer stalling when the trigger is released indicates a fault in the unloader valve. To fix the problem, remove the unloader valve from the pressure washer and inspect its various parts. Including the piston, O-rings, and springs. Also, check the valve’s settings and adjust it to the correct value. 

The unloader valve is the (mostly) black handle located at the top of the pump system. When the trigger is released, the unloader valve redirects the water in a loop to retain the pressure. If the unloader valve doesn’t work correctly, the pressure washer stalls when releasing the trigger due to pressure build-up.

To solve this stall, you need to remove the unloader valve and inspect its various parts. Mostly the problem lies in the piston, O-rings, or the spring of the unloader valve. In addition, the pressure washer can also stall when releasing the trigger when the unloader valve is set to a very high setting. 

You only need some simple tools, like a screwdriver and a wrench, to remove the unloader valve. Have some alcohol at hand cleaning the various parts. Use grease while placing the parts back in place.

How to Fix the Pressure Washer Stalling When the Trigger is Released

– Step 1. Remove the unloader valve:

The first step is to locate the unloader valve and remove it. The unloader valve is located above the pump and can be easily identified by the black handle. Unplug it using a screwdriver. Look for the U-shaped retaining pin that holds the valve in position. Remove the retaining pin and use the screwdriver as a lever to pull off the unloader valve.

– Step 2. Check the piston

To ensure the free movement of the piston, unscrew the nut that holds the piston. Disengage the spring and piston from the valve. Clean the piston and spring with alcohol to remove any dirt. Grease the piston and the spring and put them back in place.

The piston plays an important role in the unloader valve’s functioning. When the movement of the piston is restricted or stopped, the unloader valve doesn’t function properly, and the pressure washer stalls.

– Step 3. Check the valve’s settings

The unloader valve regulates the pressure in the pressure washer. The pressure is adjusted and controlled manually. If the unloader valve is set to a really high setting, it can build up very high pressure in the pump that cannot be released easily. This causes the engine to stall when the trigger is released.

To solve this problem, ensure that the engine is running correctly. Locate the pressure adjusting knob on the valve. Adjust the knob slowly to achieve the appropriate settings while holding the trigger. It would be best if you observed a maximum spike between 5% and 10%. If higher, adjust the knob further.

– Step 4: Check O-rings

O-rings deteriorate over time and cause leakage in the oil pump. This may stall the pressure washer. To solve this problem, remove the old O-rings and replace them. 

– Step 5: Place the unloader valve back

Once you have completed the previous steps, reinsert the valve and place the retaining pin to keep the valve in its place. Turn the pressure washer on and check its performance. Hopefully, after following all the steps, the pressure washer stalling problem is solved.

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