Pressure Washer motor stops running while in use, what to do?

Approx Reading Time: 8 minutes

It has been a messy, rainy week, and you have not been able to find time for a car wash or some other cleaning. Fate does not stop here; it further ruins your plans when you realize that your pressure washer motor is not working correctly. What do you do? There is no need to panic. We will help you with this blog article. Troubleshooting this problem is not as complicated as it seems, and you can do it yourself easily. In this article, we put together all the plausible issues and how to fix them.

Pressure Washer motor stops running while in use:

  1. A Clogged Carburetor does not allow a suitable amount of air-fuel mixture to be drawn for complete combustion.
  2. A Clogged Fuel Cap does not allow air to enter and mix with fuel properly.
  3. The fuel Filter may clog due to unused fuel that stays there for an extended period.
  4. The Air Filter may be blocked because of dust particles inhibiting the complete combustion.
  5.  The Spark arrestor may clog due to soot.
Pressure Washer motor stops running while in use, what to do? 1
(CC BY-SA 2.0) by OlgerFallasPainting

If the pressure washer motor stops soon after starting and idles, the most probably cause is incomplete combustion. Because of that, the washer does not pump the water & fails to yield high pressure. This problem is further associated with several reasons. We will analyze them separately.

You might be thinking about coping with this situation; do not worry. We are full of some easy ways to resolve your issue. Just have a look!

Common Troubleshooting Steps:

Pressure engine’s solutions generally include cleaning and replacing the various components such as carburetor defects, filters, spark arrestors, etc. We have enumerated the following troubleshooting steps, which will help you to fix your setback.

1. Clogged Carburetor.

One of the most often cause of the motor not working is the clogging of the carburetor. A carburetor usually clogs due to leaving fuel in the pressure washer for an extended period. Over time, some of the fuel constituents may evaporate, leaving behind a thicker, stickier substance. This sticky fuel can choke the carburetor and cause the engine to stall. In severe cases, this can cause the engine to sputter out and may seize entirely.  

– Solutions:

a) Carburetor Cleaner:

If the carburetor clogs, try cleaning it with carburetor cleaner.

  • Remove cover: Take out the front cover and air filter door to make the carburetor visible.
    • Detach fuel lines: Dispatch the fuel lines cautiously to prevent fuel leakage and take out the main assembly component.  
    • Disassemble the carburetor: Carefully disassemble the screws and jets. It is better to perform a recording and clips of the ongoing procedure, so it is easy to assemble each part back onto its original place.
    • Examine jets: After removing the constituent parts of the assembly, you should analyze them individually for dust particles and dirt that serves the purpose of improper drawl of the carburetor’s air-fuel mixture.
    • Unclog with cleaner: Use carburetor cleaner liquid to unclog the jets. Compressed air is also used for cleaning the holes and tubes.
    • Reassemble: Once you are done with the cleaning, assemble the carburetor and fix it back onto its original place.
b) Replace the carburetor and take preventive measures

If cleaning the carburetor is not fruitful, reconstruct or substitute the entire carburetor and take preventative measures for future use.

  • Fresh Gas: Always use fresh fuel to avoid some major problems regarding stalling. Do not keep the fuel for an extended period in the cabin.
    • Fuel Stabilizer: Use fuel stabilizers to avoid the residual formation in the compartment, as it comprises chemical additives that enhance the residual fuel life.
    • Carburetor Cleaner: Carburetor Cleaners are readily available in the market, acting as anti-rust agents and cleaning the grease.

2. Clogged Fuel Cap:

When the engine starts, fuel consumption occurs, reducing the fuel level in the tank. The fuel cap uses a small outlet for the intake of air. If the fuel cap vents get clogged, it prevents the air from entering the tank and creates a vacuum. The flowing fuel to the carburetor is stopped, and this phenomenon is known as stalling.

– Solutions:

  • Start without fuel cap: If the fuel cap vent clogs, lose the fuel cap, and then start the engine. If it allows the engine to stay running, it is likely an issue, and we need to replace the fuel cap vent as early as possible.
    • Clean the fuel cap: Another efficient way to unclog the cap is to dip it into the acid bath, which widens the outlet and gives proper air for proper combustion.

3. Clogged fuel Filter:

There might be some clogging in the fuel filter. It occurs due to old and bad fuel in the tank or an extended period. Over time, some of the fuel constituents may evaporate, and residue remains in the tank. This residual fuel can clog up the fuel filter and cause the engine to stall.

– Solutions:

  • Drain and replace the fuel: If you left the old fuel in the pressure washer, first drain the old fuel from the fuel tank and replace it.
    • Fuel stabilizer: Always use fresh fuel with fuel stabilizer and replace the fuel filter in extreme naked black residue conditions.

4. Blocked Air Filter:

If clogging occurs in the air filter, the air-fuel mixture ratio is disturbed. As a result, the engine may stall.

– Solutions:

  • Clean: The roots blower or pneumatic pressure cleaner is used to clean the washer to remove the dust particles. However, it is recommended to have a cleanup once in 2 months or when it is needed.
  • Replace: To enhance the carburetor’s life must replace the air filter once a year.

5. Clogged Spark Arrestor:

A small screen inhibits the engine from emitting sparks. Over time, there might develop a carbon coating at the screen. A clogged spark arrestor may cause damage to the engine, even stalling in some cases.

– Solutions:

  • Wire brush: Use the wire brush to unclog the spark arrestor.
    • Replace: In extreme conditions, replace the spark arrestor after some months to have the washer’s proper working.

Some Additional Problems:

● Nozzle Issues:

The prime part from where water ejects out of the machines is the nozzle. Carefully select the nozzle size as it defines many essential parameters like range and pressure, which is our primary concern. Clogging its size reduces, which may yield high pressure and cause the washer to shut off immediately after starting. Thus, it may damage the motor severely.

– Solution:

The ideal solution to this problem is to choose a suitable new nozzle and replace the worn-out nozzle. In this way, you can also ensure the same water temperature for your cleaning each time (ideally cold water only).

● Defective Spark plug:

Another cause for the pressure water motor to stop is the malfunctioned spark plug. The spark plug comprises two leads that generate an electric arc, which eventually produces the spark.  The incomplete ignition gives the motor initial start for a moment and then stalls. The buildup soot can also affect spark creation. Furthermore, the electrode can also weaken due to wear and tear.

– Solutions:

  • Examine the spark plug that its components are working accurately or not. Also, notify the carbon buildup and the damaged electrodes, which may cause the issue.
  • As you cannot repair a defective spark plug, it is recommended that you should refurbish your spark plug every once a year.

Frequently Asked Questions:

1. What are we supposed to do if the Electric pressure washer starts then stops?

Replace the air filler immediately if clogging has occurred in it. If the air filler is okay, then check the unloader valve of your engine. The engine turns on and off when the unloader valve fails, so check it regularly. If the problem persists, then try replacing the capacitor. It will help you solve your problem in most cases.

2. Why does the stalling of the pressure washer motor occur under load?

Majorly it is because of the faulty unloader valve of the engine. A faulty unloader valve does not let the water release, thus increases the pressure inside the pump. We also need to check the water diversion of the unloader valve. If the water flow diversion is not proper, then we have to replace the unloader valve at its earliest.

3. On pulling the trigger, why does the pressure washer turns off?

If the pressure washer turns off when we release the trigger, the issue is obviously in the unloader valve, causing stalling. Troubleshooting this problem is quite simple, and you can sort it out quickly.

4. Why does the pressure washer cut off when spraying?

If water pressure inside the pump exceeds its limit, pump damage may occur, which causes the pressure to cut off. Moreover, high pressure can also cause difficulty in the rotation of the engine’s pump and stalling. Thus, it cuts off while spraying.


Combustion is the core of a pressure washer and likely to be the core reason for a faulty washer. The clogged components like carburetor valves, air, fuel filters, and spark arrestors are the primary cause of stalling. The tuning and cleaning of these vital parts are recommended timely. In severe cases, these defective parts must be replaced well in time to prevent the abruption in the washer system. Proper maintenance and preventive measures enhance the life of the components and their functionality.