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Pressure Washer Troubleshooting

Last updated on Dec 19, 2024

Whether you run a pressure-washing business or use a pressure washer for your company's maintenance needs, ensuring your unit is operating properly is essential. When issues like failure to start, low water pressure, or pump problems arise, troubleshooting common causes can help restore optimal performance. Addressing these complications promptly reduces downtime and keeps your equipment running efficiently, ensuring smooth operations. We've outlined common issues with commercial pressure washers and possible solutions to help you diagnose and resolve minor malfunctions and get your equipment back in action.


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Use the following links to troubleshoot your pressure washer:

  1. Pressure Washer Engine Will Not Start
  2. Pressure Washer Has Low Water Pressure
  3. Water is Leaking from Pressure Washer Pump
  4. Oil is Leaking from Pressure Washer Pump
  5. Pressure Washer Is Not Dispensing Detergent
  6. Pressure Washer Is Making Unusual Noises

Pressure Washer Engine Will Not Start

pressure washer on concrete

If the engine of your pressure washer is not starting, it can be due to several different issues. Below is a list of common causes and troubleshooting steps to help you identify and resolve the problem.

  • Engine switch is in the "OFF" position: Turn the engine switch to the "ON" position.
  • Fuel valve is in the "OFF" position: Some pressure washers have a fuel shut-off valve that prevents fuel flow when the engine is not in use. If it's in the "OFF" or "CLOSED" position, the engine will not start. Check the fuel valve and ensure it is in the "ON" or "OPEN" position to allow fuel to flow to the engine.
  • Fuel tank is empty: Check your fuel tank to see if it's empty or filled with old, degraded gas that has been sitting too long (gas older than 30 days for most units). Fill or replace with fresh fuel.
  • Low engine oil level: Some engines have an oil sensor that prevents the engine from starting if the oil level is too low or if the wrong oil type is used. Check the oil level and ensure it's at the proper level. Add oil if necessary. Verify that the correct type of oil is being used for your engine as specified in the user manual.
  • Engine choke is in the incorrect position: The choke regulates the air-fuel mixture during startup. If the choke is not set correctly, the engine may fail to start. Each model has different choke settings and the correct position will depend on the engine's temperature, so refer to your owner's manual to properly troubleshoot this.
  • Clogged fuel line: A clogged fuel line or filter can prevent fuel from reaching the engine. Check the fuel line for any visible kinks, cracks, or obstructions. If the fuel filter is clogged, clean or replace it. For a blocked fuel line, clear the obstruction by gently blowing compressed air through it.
  • Malfunctioning spark plug: A spark plug breaks down over time, and a dirty, worn-out, or disconnected spark plug can prevent the engine from starting. If the spark plug lead is not attached to the plug, connect and try to restart. If it's dirty, clean it with a wire brush. If the spark plug is damaged or old, replace it with a new one.

If the issue is related to degraded fuel, make sure you're storing the gas correctly. Use a fuel stabilizer to extend the shelf life of the gasoline if you know you won't be reaching for it for a while.

Pressure Washer Has Low Water Pressure

pressure washer on floor with bubbles spraying up

If your pressure washer is losing pressure or creating low to no water pressure, run through this list of issues to troubleshoot.

  • Clogged nozzle: Over time, dirt and debris can clog the nozzle in your power washer, causing a significant reduction in water pressure, the unit to pulsate while spraying, or both. Get in the habit of checking the nozzle before each use, as using a pressure washer with a clogged nozzle can damage the pump. Check your owner's manual for specific directions on how to clean the nozzle.
  • Clogged water inlet filter: Inspect the water inlet filter for dirt and debris before each use and clean or replace it when necessary. Check your owner's manual for specific directions on how to clean the filter.
  • Insufficient water supply: The pressure washer should be connected to a hose with adequate water flow (usually at least 5 gallons per minute for most units).
  • Kinks in the hose: Check the hose for kinks, twists, or damage. Even a slight obstruction in the hose can reduce water flow and pressure.
  • High-pressure hose is too long: The longer the hose, the lower the pressure that arrives at the pressure washer. Check your unit's manual to ensure you're not exceeding the maximum hose length.
  • Air trapped in the system: Air trapped in the pump or hose can cause intermittent or low pressure. Turn off the pressure washer and allow it to sit for a few minutes. Release any pressure by pulling the trigger on the spray gun to allow air to escape from the system. Restart the unit and test the water flow.
  • Malfunctioning unloader valve: The unloader valve bypasses flow in the pressure washer and may malfunction, leading to low or no pressure. Check if it is dirty, worn, or incorrectly positioned. Clean, replace, or adjust as needed.

Water Leaking from Pressure Washer Pump

If water is leaking from the pressure washer pump, it's essential to identify the cause quickly to prevent further damage and conserve water. Most often water leakage is caused by worn seals and/or loose connections, which are easy to remedy. Here's a list of troubleshooting tips to work through:

  • Loose or damaged hose connections: A loose or damaged connection between the hose and the pressure washer or the spray gun can cause water to leak. Turn off the pressure washer and disconnect the hoses. Check for loose connections and tighten them securely. Inspect the O-rings at the hose connections for damage, and replace them if necessary. Check the hose for visible cracks, holes, or damage, and replace it if needed.
  • Faulty or worn spray gun: The spray gun may have a damaged seal or faulty trigger, causing water to leak. Inspect the spray gun for any cracks, worn-out seals, or damage. Check the connection point between the gun and the hose for leaks, and ensure it's tightly secured. If the trigger or any spray gun parts are damaged, replace them.
  • Clogged or broken nozzle: A clogged nozzle or spray tip can cause water to leak from around the nozzle area, especially if water pressure builds up behind a blockage. Turn off the pressure washer, remove the nozzle, and clean any debris, dirt, or buildup from it or the spray tip. If the nozzle is damaged or worn, replace it with a new one.
  • Cracked pump seals: Check the pump seals for wear and tear. If the seals are damaged, replace them.
  • Cracked pump: Inspect the pump for visible cracks or signs of damage. If the pump is cracked, it may need to be replaced entirely. Consult an authorized professional if you suspect a pump failure.

If you're storing the pressure washer during cold weather, drain all the water from the pump, hoses, and nozzles to prevent freezing and cracking. Damage to the pump and seals is more common in winter due to improper storage.

Oil Leaking from Pressure Washer Pump

If you notice oil leaking from the pressure washer, it could be an issue of loose or worn parts around the pump or excess oil levels. We've provided a list of areas to troubleshoot below. If the issue persists after these checks or if you're unable to resolve it yourself, it's best to consult a professional technician or replace the pump if it's beyond repair.

  • Overfilled oil level: If the pump crankcase, located within the pump's casing, is overfilled with oil, the excess can leak from the vent cap during use. Check the oil level and ensure it is within the recommended range. If the crankcase is overfilled, drain the excess oil until it reaches the correct level. Always follow the manufacturer's guidelines for oil levels and use.
  • Damaged oil seals or gaskets: Inspect the oil seals and gaskets around the engine and pump for signs of wear or damage and replace them with new ones as needed.
  • Loose or worn oil drain plug: Drain plugs can become loose over time from system vibration. Check the oil drain plug for tightness and ensure it is properly secured. If the plug is damaged, replace it with the correct part.
  • Loose or worn oil cap and oil fill plug: Ensure the oil cap and oil fill plug are properly tightened. Check for any cracks or damage in the cap. If the cap is damaged, replace it with a new one. Make sure the oil fill plug is properly seated and sealed.
  • Vent plug is clogged: Clean the vent plug by blowing air through the vent to remove any debris or blockages. If the issue persists, replace the plug.

Pressure Washer Is Not Dispensing Detergent

man pressure washing outside windows with soap suds

If detergent isn't being drawn in or dispensed from your pressure washer, there are several things you can check to diagnose and fix the issue:

  • Check the detergent tank: Ensure that the detergent tank is filled with the correct detergent and that it hasn't run empty. If the tank is empty or nearly empty, refill it with the appropriate detergent for your pressure washer.
  • Incorrect nozzle: Ensure you're using the correct nozzle for detergent dispensing. Most pressure washers require a low-pressure nozzle (usually a black tip) to allow detergent to be drawn in. If you're using a high-pressure nozzle, the detergent won't dispense.
  • Pressure setting is too high: If the pressure is too high, the detergent may not be drawn into the system. Switch to a lower pressure setting, pull the trigger, and see if it begins to flow.
  • Detergent filter is clogged: Check the filter and clean if necessary.
  • Detergent filter is not submerged in the detergent: Check to ensure the detergent end of the detergent siphon hose is fully immersed in the detergent.
  • Detergent is too thick: If the detergent is too concentrated, it will not be able to pass through the system. Dilute to the same consistency as water.
  • Detergent has dried inside the injector: If the detergent has dried in the system, it can cause blockages. Flush the detergent system with clean water to remove residual soap and clear the line.

Pressure Washer Is Making Unusual Noises

Strange noises, from rattling to high-pitch squealing sounds, can be caused by a variety of different issues with your pressure washer. Here's a list of possible issues that can cause your pressure washer to make unusual noises:

  • Air in the water line: One of the most common reasons for strange noises, such as a high-pitched squeal or whistling, is air in the water line. This typically happens if there's a loose connection or if the pressure washer has been idle for some time. Run the pressure washer with the water turned on but the trigger gun released (off). Let the water flow through for a minute to expel any trapped air.
  • Low water supply or blockages: If the water supply is insufficient or there are blockages in the hoses, the pressure washer may struggle to operate and create strange noises. Ensure the water supply is turned on fully and flowing without obstruction. Look for kinks, blockages, or damage to the hoses that could be restricting water flow.
  • Blocked or clogged nozzle: A blocked or partially clogged nozzle can cause an irregular sound, as the pressure washer struggles to push water through. Clean the nozzle if there is any debris, buildup, or blockages.
  • Loose hose connection: Inspect all hose connections and fittings for any leaks. Air entering the system through loose or cracked hoses can cause noisy operation. Tighten or replace as needed.
  • Worn pump or internal components: The pressure washer pump may make unusual noises if internal parts such as seals, valves, or pistons are worn or damaged. Inspect the pump and surrounding areas for loose connections or worn seals. If you suspect internal pump issues, it's best to have the pump professionally inspected or replaced if needed.

Back to Top

Pressure washing is crucial for maintaining the cleanliness, safety, visual appeal, and long-term integrity of outdoor surfaces, such as driveways, sidewalks, parking lots, and the exteriors of buildings. To ensure your pressure washer remains in optimal condition and ready for use at any time, it's important to perform regular maintenance. This includes cleaning nozzles, seals, and filters, inspecting for loose connections, and monitoring fuel levels. Proper upkeep will ensure your unit operates efficiently, delivering top-notch results every time.

Check your pressure washer's owner's manual for specific instructions and protocols before performing any repairs or maintenance to the unit. If you still have trouble with your pressure washer after these fixes or don't feel comfortable troubleshooting yourself, contact an authorized repair professional.

The information provided on this website does not, and is not intended to, constitute legal advice. Please refer to our Content Policy for more details.

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