Why isn’t my pressure washer building pressure? Helpful tips

A pressure washer works so well cleaning the exterior of your house because it uses much higher pressure than a regular hose. But still, a lot of pressure washer users complain about their pressure washer not giving the pressure they expect or used to provide. There can be many reasons for this problem. We have listened to the most common causes and how to diagnose and fix your pressure washer low pressure.

Why isn’t my pressure washer building pressure:

Generally, the most common reason for a pressure washer not building pressure is that it does not get enough water. This can be due to a hose problem, leakage, or blockage. Another reason can be air can get trapped inside the pressure washer pump or a problem with the nozzle. Less common is a problem with the pump or the engine.

How to diagnose low pressure on a pressure washer?

To diagnose low pressure on a pressure washer, you must first determine the type of pressure you receive. For pulsating low pressure, check the pump for any visible damage. For unsteady low pressure, examine the pump inlet for any air leakage and ensure that your water source supplies enough water. For steady low pressure, pump starvation and a loose belt could be the reason behind low pressure.

Below, we look at the different steps to diagnose the low water pressure in your pressure washer. Low water pressure can appear with different symptoms, like pulsating, steady, and unsteady low pressure. First, we will discuss each element individually and then the components that you need to check to diagnose the cause of low pressure.

● Low pressure and Pulsating

Pulsating low pressure feels like a hard vibration of a spray gun during pressure washing, also known as cavitation. This pulsating low pressure mainly occurs due to a pump malfunction. The cylinder of your pump does not produce enough pressure and misfires, resulting in a decrease in pressure.

– Diagnose: Check the pump

You can diagnose the problem in the pump by first checking the head of the pump. If there is no visible damage, check your machine’s valve for any dirt blockage. Also, check the inline filter because with time, dirt and debris gather inside the filter, and they increase significantly after a couple of washings. As a result, your pressure washer runs with very low pressure.

After clearing the dirt and debris from the pump valve, move toward the seals and check for excessive wear. Then inspect the piston seals and if there is any water leakage. If there is, it means that your seals are damaged, which is the reason for the low pressure.

● Unsteady low pressure

Unsteady low pressure is basically the water coming out of the nozzle with the pressure lower than normal. The pressure may also suddenly change from low to high. This unsteady low pressure can be due to some fault with the water intake system or when air gets trapped in the intake line.

– Diagnose: Check the pump inlet

First, you need to check for any air leakage to diagnose the reason behind this low water pressure. To do this, ensure that your water source supplies enough water for the pump inlet to be completely immersed below the water level. Also, ensure that no air enters the intake line from the chemical injector and that it is closed completely.

Check the hose points for any cracks by giving them a firm shake. Weak or cracked hose barbs will bend or break. Then inspect the suction lines for any cracks or heat damage. Finally, remove the feed line from the water source and attach it to the garden hose. The hose pressure will reveal any leaks, so you do not need to run the pressure washer.

● Steady low pressure

Steady low pressure happens when a pressure washer produces a lower pressure than usual. There can be many reasons behind this problem, and you can diagnose them by following the steps below mentioned.

– Diagnose: Pump starvation

Pump starvation is one of the main reasons behind low water pressure from the machine’s outlet. Ensure the intake lines are not kinked or clogged and supply enough water to the pump. Also, if your hose is damaged, it will not produce enough GPM for the pressure washer to run at normal pressure.

– Diagnose: Loose belt

If the belt of your machine is loose or slipping, it results in a decrease in water pressure. You can fix this problem by tightening or replacing the belt.

Why doesn’t my pressure washer have any pressure?

In general, a damaged pump, engine problem, and motor malfunction are the most common reasons behind your pressure washer having no pressure. Besides these problems, using hot water in a cold water pump or a loosened or damaged spark plug can also lead to no pressure in your pressure washer.

If your pressure washer produces low or minimum pressure, it could mean some components of your pressure washer are not working correctly. Instead of hiring an expert, you can troubleshoot your machine yourself.

● Reason 1: Spark plug (gas pressure washer only)

If your pressure washer gas engine is running, it does not sound ok. And it is not producing or only low pressure. First, check your machine’s spark plug. Examine the wires of the spark plug; if they are loose, you can tighten them. Also, check for any corrosion at the edge of the plug. You can remove this corrosion using a brush, and if it is widely spread, replace the plug.

● Reason 2: Carburetor problem (gas pressure washer only)

If the sparkplug looks ok, but the engine does not run well, the carburetor could be the reason. The engine will work less optimally if dirty, resulting in less or no pressure. If your engine is not throttling up, this is a clear sign.

Disassemble the carburetor and clean it using a carburetor cleaner. Ensure that you do not use bad gas. Bad gas is gas that has been stored for multiple months. Add fuel stabilizer if you plan not to use gas for an extended period.

● Reason 3: Air filter (gas pressure washer only)

Another reason for the engine not working well is a dirty air filter. Remove the air filter and check it. If it is dirty, clean it or replace it. A paper air filter needs to be replaced.

● Reason 4: Hot water in a cold water pump

Another reason for the missing pressure in your pressure washer can be pump damage. There are pressure washers that can be used with cold water only. If these pressure washer pumps are exposed to hot water, it can damage the pump, which causes low pressure in your washer.

If this is the case, replacing the pressure washer pump is probably the only solution.

● Reason 5: Damaged pump

Sometimes using the wrong type of oil or lubricant or running the machine with old dirty oil can damage your pressure washer’s pump. You must check and change the oil of your pressure washer regularly. A gas engine has an oil filter to clean the oil when running.

A pressure washer pump does not have it. So when the oil is dirty, it needs to be replaced. Some cheaper pressure washers are using a closed-loop pump oil system. For those machines, you can not replace the oil.

If you use your pressure washer without water, it will run hot. Water cools the pump. When running hot, it can lead to a worn pump. In this case, you need to replace the pump.

● Reason 6: Motor malfunction (electric pressure washer only)

In an electric pressure washer, the electric motor is the source that powers the pump works that generate the high water pressure. If your motor malfunctions, the pressure washer ends up losing pressure. To check that the motor of your electric pressure washer is working fine, push the trigger a couple of times.

Your motor is fine if your pressure washer produces high and low pressure.

How do you fix low pressure on a pressure washer?

The first step for fixing the low pressure of your pressure washer is changing its oil and cleaning the filter. If the pressure of your washer has still not increased, check the water supply hose and adjust the unloader valve to your desired pressure. The nozzle of the pressure washer is often worn out, which causes low pressure. You can fix this problem by replacing the nozzle of your pressure washer.

● Solution 1: Maintenance of your pressure washer 

The first solution to fixing the low pressure on your pressure washer is to maintain it properly. Each machine needs maintenance to make it last longer. This applies both to gas and electric pressure washers. Gas pressure washers require a lot more maintenance than their electric cousin.

To fix the low pressure of your washer, you should give proper attention to the maintenance of your engine, pump, gas pressure washers, and the engine. Check and change the oil at regular intervals.

Your pressure washer’s filter can catch many dust particles during cleaning. This can result, over time, in lower pressure. Check and clean the inlet filter of your washer regularly. Also, check if the nozzle you use wear and tear. If you have an additional one, use that one and see if there is a difference.

● Solution 2: Fixing the hose

If your pressure washer is still producing low pressure after checking and changing the oil and filters and cleaning the nozzle, the next step is to check the hose and the water supply going into the machine. Most pressure washers need at least a water supply of 0.9 gallons per minute.

According to most experts, the recommended diameter of the supply hose should be ¾ inches to maintain the correct pressure. If the washer’s pressure is still low with a ¾-inch diameter hose, check for any blockage in the hose. Disconnect the hose from the inlet valve, and check if the supply is sufficient. Also, remove dust and debris from the inside of the inlet filter.

● Solution 3: Replace the nozzle

Another solution to fix low pressure is to replace the nozzle at the end of the trigger wand. Sometimes, the nozzle becomes worn, resulting in an unusual spraying pattern of water. This worn-out nozzle can also cause low pressure because the holes widen with time. As these holes widen, more water flows through the nozzle and decreases the pressure of the water.

Nozzles will wear over time with regular use and must be replaced. It is recommended that you have several nozzles on hand.  This allows you to easily change the nozzle if you see any decrease in pressure and to test other nozzles to check whether the pressure is decreased due to the nozzle.

● Solution 4: Adjust the unloader valve

The main function of the unloader valve is to divert the water flow from the pump toward the bypass. This unloader valve can sometimes be the reason for low water pressure.

If replacing the nozzle did not make a difference, we must check the unloader valve. Adjust it in small steps to increase the pressure of the pressure washer. Connect a pressure gauge when adjusting the unloader valve to ensure safe pressure.

During the unloader valve adjustment, ensure that the machine is running and pull the trigger to allow water to flow through the machine. If adjusting did not help, the valve could be broken. In that case, it needs to be replaced.

Pressure Washer Failing to Build Sufficient Pressure

Pressure washers are essential for cleaning and maintaining various surfaces, from concrete driveways to wooden decks. However, when a pressure washer is not building pressure, diagnosing the issue can be frustrating and challenging.

• Inspect the Nozzle for Clogs and Debris

One of the most common reasons a pressure washer is not building pressure is due to a clogged or blocked nozzle. Debris, dirt, and other foreign objects can easily get trapped in the nozzle, preventing the water from being sprayed at high pressure.

I recommend: Regularly inspecting and cleaning the nozzle to ensure it is free from clogs or debris. If you find a dirt or grime buildup, use a small wire brush or a similar tool to clean the nozzle gently. See this link for more information on maintaining your pressure washer.

• Check the Water Supply

Another reason a pressure washer is not building pressure can be due to an inadequate water supply. If the water supply to the washer is restricted, it will not function properly and result in low pressure.

I recommend: Ensuring that the water supply is not obstructed and that there is sufficient water flow to the pressure washer. You can check the water flow by removing the hose from the pressure washer and allowing it to flow through it for a minimum of 30 seconds.

This will help to determine if there are any blockages or restrictions in the waterline. Furthermore, use a hose with an adequate diameter for your pressure washer.

• Examine the Pump for Damage or Wear

The pump is an essential component of a pressure washer, and if it is damaged or worn out, it will not be able to generate the required pressure. Frequent use or lack of proper maintenance can cause the pump to wear down over time, leading to reduced performance.

I recommend: Inspecting the pump for any visible signs of damage, such as cracks, leaks, or corrosion. If any damage is found, replacing or repairing the pump to restore the pressure washer’s functionality is essential.

It is also crucial to follow the manufacturer’s guidelines for pump maintenance, such as regularly changing the pump oil and keeping it clean from debris.

• Verify Proper Unloader Valve Setting

The unloader valve releases excess pressure when the pressure washer is not used. However, if the unloader valve is not set correctly, it can cause the pressure washer to lose pressure even while in use.

I recommend: Checking the unloader valve and ensuring it is set to the appropriate pressure for your specific pressure washer model. If you are uncertain about the correct setting, refer to the manufacturer’s guidelines or consult a technician.

• Evaluate and Replace Damaged or Leaky Hoses

Leaky or damaged hoses can significantly affect the pressure washer’s performance by allowing high-pressure water to escape before it reaches the nozzle. Additionally, kinked or twisted hoses can restrict the water flow, reducing pressure.

I recommend: Regularly examining the hoses for any signs of damage, such as abrasions, cuts, or leaks. If there is a leak or another type of damage, it is crucial to replace the hoses immediately to restore the pressure washer’s performance.

Additionally, avoid kinking or twisting the hoses during use and storage to maintain proper water flow and pressure.

• Consider the Use of Proper Detergent and Soap

Using the wrong type of detergent or soap can negatively impact the pressure washer’s performance. Some detergents are specifically designed for low-pressure applications, and using them in a high-pressure washer can cause the pressure to decrease.

I recommend: Utilizing only detergents and soaps designed explicitly for use in pressure washers. Also, follow the manufacturer’s guidelines for the recommended detergent-to-water ratio.

• Seek Professional Assistance

If you have tried all the above recommendations and still have issues with your pressure washer not building pressure, it may be time to seek professional assistance. Certain internal components, such as seals or valves, might need to be replaced, and only a professional technician can perform these repairs.

I recommend: Contacting a certified repair technician or the pressure washer manufacturer for further assistance. They can help diagnose the issue and determine the best action to restore your pressure washer to working order.

In conclusion, pressure washer problems can be frustrating, but knowing the common issues and how to address them can efficiently restore your pressure washer’s performance. Regular maintenance and care are essential to extend the life of your pressure washer and ensure optimal performance at all times.