Pressure Washer With No Pressure? Why Your Pressure Washer’s Not Building Pressure

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Pressure washers are terrific devices to help clean dirt off surfaces that your normal garden hose wouldn’t be able to, due to their high pressures. But, a very common issue is when the pressure washer won’t build pressure, and this can be for a number of reasons.

This article will provide you with all the relevant information on why pressure washers may not build pressure and how to fix them if they don’t!

Why Does My Pressure Washer Have No Pressure?

It’s typical that the most common reason for a pressure washer not building pressure is either a damaged pump, an engine problem, or motor malfunction that tends to be the most common reasons. Other reasons may involve using hot water in a cold water pump or a loosened or damaged spark plug that leads to no pressure being in your pressure washer.

If your pressure washer produces low or minimum pressure then it’s likely that some of your components of the pressure washer are not working correctly. Instead of spending mass amounts of money on an expert fixing it for you, you should be able to troubleshoot your machine yourself.

Here are the most common reasons why your pressure washer won’t build pressure:

  • Air Filter
  • Carburetor Problem
  • Damaged Pump
  • Hot Water in Cold Water Pump
  • Motor Malfunction
  • Spark Plug

Let’s take a look at each in more detail!

Air Filter

A dirty air filter can be a big reason as to why the engine is not working properly. This is only an issue with gas pressure washers, and if you are able to diagnose this issue, you should remove the air filter and check it.

If the air filter is dirty then you should either clean it or replace it so that the air filter works effectively and doesn’t block flow. In most situations, it may be a matter of replacing the paper air filter inside the device and you’re good to go!

Carburetor Problem

It’s possible that if the carburetor, on gas pressure washers only, is dirty then the engine will work less efficiently. With this reduced quality of operation, it’s likely that the pressure washer will be operating with less or no pressure.

If the engine is not throttling up, this will be a very clear sign. You should disassemble the carburetor and clean it using a suitable carburetor cleaner. It’s very important to not use bad gas that has been stored for many months. It may be wise to also add some fuel stabilizer if you plan not to use the gas for an extended period.

Damaged Pump

If using the wrong type of oil or lubricant, or even running the machine with old dirty oil, it’s possible that you will damage the pump of your pressure washer. You, therefore, must check and change the oil of your pressure washer regularly.

A gas engine has an oil filter to clean the oil when it is running while the pressure washer pump does not have it. If the oil becomes contaminated, it will need to be replaced. But the issue here is that some pressure washers use a closed-loop pump oil system where you will not be able to replace the oil.

Pressure washer pumps depend on water lubrication, and so, if the water is hot it will not cool the pump and this will lead to premature wear and tear on the pump. It’s estimated that at least 90% of problems with the pump lead to a created pressure loss issue. Pumps will, over time, gather minerals and dirt. The aim of the inline filter is to protect the pump from the contaminants that may harm it.

With time, the debris in the air filter will start to prevent the normal water flow, and as a result, your pressure washer ends up losing some of its pressure. To fix this issue you need to pay attention to the air filter, as I’ve previously described. On top of this, it’s advised to clean the pump from time to time, to ensure that the pump remains healthy.

Hot Water in Cold Water Pump

Leading on from the last point, I mentioned how pressure washer pumps require lubrication from cold water in order to not overheat and wear. Pressure washers, for this reason, can not be used with hot water as this will damage the pump significantly.

Exposing pressure washer pumps to hot water will not only damage your pump but also lead to low pressure in your washer. If your pump becomes damaged by hot water you may be left with only one solution, replacing the pump. Some pressure washers may be rated for hot water, and in this case, if you were to supply the pressure washer with cold water you may have issues getting the desired pressure.

Even when using a hot water pressure washer, you should never use water that has a temperature beyond 100 degrees Fahrenheit because this heat is bad for the entire system. To avoid any unwanted events, you should turn off the pressure washer and allow the water to cool down before operation.

Motor Malfunction

In electric pressure washers only, the electric motor is essential in powering the pump so that the high water pressure can be generated. If you were to experience motor malfunctions, it’s guaranteed that you will lose water pressure as a result.

To check that your motor is working as it should be you should push the trigger a few times. If the pressure washer produces high and low pressure, this is a good indication that your motor is fine. If the motor cannot reach its rated maximum pressure then you know you have a problem, and should contact a technician.

The same can be said for the engine component of a gas pressure washer, where that component is the workforce that generates power. Follow the same procedure as with the electric motor, by pulling the trigger a couple of times to see if the pressure washer is capable of reaching maximum pressure.

Spark Plug

The spark plug is typically the first component to check if your pressure washer is running but doesn’t sound like it should and is not building pressure. Spark plugs will be found on gas-powered pressure washers only, and you should examine the wires of them to see if they are loose and need tightening.

When examining spark plugs, look for signs of corrosion at the edge of the plug and remove it with a wire brush if necessary. If the corrosion is so widespread then it is generally advised to replace the whole spark plug.

The YouTube video below describes a few additional reasons as to why the pressure washer has no water pressure.

How to Fix Pressure Problems on a Pressure Washer

In the common reasons for a pressure washer having no pressure, I have just described how you can fix a few of the issues, by changing the oil and cleaning the air filter. But, I would now like to discuss some further troubleshooting tips that could help you get your pressure washer’s pressure back to its optimum. The additional measures include:

  • Adjustment of the Unloader Valve
  • Fixing the Hose
  • Regular Maintenance of the Pressure Washer
  • Replacing the Nozzle

Let’s take a look at each in more detail!

Adjustment of the Unloader Valve

Unloader valves have one main function of diverting water flow from the pump towards the bypass, and so, if the unloader valve is not set up correctly, it is likely to be a reason for low water pressure. The unloader valve should be adjusted in small steps to increase the pressure of the pressure washer. To ensure a safe pressure, you should connect a pressure gauge for the adjustment.

During the unloader valve adjustment, you must ensure that the machine is running and pull the trigger so that a flow of water is allowed through the machine. If this adjustment does not help, and you are unable to regulate the pressure, it’s possible that the valve is broken and will need replacing.

Fixing the Hose

The hose can be a likely source of the reduced pressure if you have already conducted other checks. While checking the hose, you should also check the water supply.

You will have two hoses to check, the garden hose which is to supply water to the inlet valve on the pressure washer, and the power hose which takes the water from the outlet valve and delivers it to the wand. If either of these hoses becomes faulty you will lose pressure, and so, both should be inspected for leakage.

You cannot use a hose that is dissimilar in diameter and will have to stick to the recommended diameter. If you don’t know the diameter, then you should check the user manual. Most experts and manufacturers will recommend that supply hose diameters should be 3/4″ to maintain correct pressures. If the pressure washer’s pressure is still low with a 3/4″ hose then you must disconnect the hose and check for any blockages. Going back to the filter and ensuring that is clean if you haven’t already too will help.

Regular Maintenance of the Pressure Washer

It doesn’t matter whether you have a gas or electric pressure washer, regular maintenance procedures will help to make the pressure washer last longer as well as avoiding situations where the pressure washer can’t build pressure. Gas pressure washers will require additional maintenance than electric pressure washers due to their additional components.

Proper attention to the maintenance of your engine/motor and pump will help to fix the low pressures. Checking and changing the oil at regular intervals, inspecting the filter of the pressure washer for contaminants, cleaning when necessary, and checking components for signs of wear and tear are all but a few important steps to take.

Replacing the Nozzle

It may be necessary to replace the nozzle at the end of the trigger want to fix your low-pressure problem. It’s possible for the nozzle to become worn over time and result in an unusual spraying pattern of water. A clogged nozzle will fail to deliver the desired pressure, and you should be able to judge if yours is clogged or not by the change in its spray pattern, typically uncontrolled and a spray of curve water.

You must remove, inspect, and clean the nozzle if necessary. It may be that the nozzle is worn-out beyond repair and will need replacing. This worn-out nozzle will also likely be the cause of low-pressure because of the holes in it that will widen over the course of time. When these holes widen, more water will flow through the nozzle, and so, the pressure of the water will decrease.

It’s typically advised to always have a number of nozzles on hand to be prepared to replace the one in use when it wears over regular use. Having additional nozzles at hand also allows you to compare, or test against one another, to see if the pressure is decreased due to one of the nozzles, and if it is, you can simply replace it with the optimum nozzle.

If the nozzle appears to be fine, but the spray pattern is still unusual, it may be that the wand itself is the one generating the issue. If the wand is clogged it won’t be able to deliver the necessary pressurized water flow. In this situation, you will need to clean the wand and replace it if found to be out of working condition.

This YouTube demonstration below provides a quick and easy method for fixing your pressure washer’s no pressure issue in 60 seconds, though, this will only work with certain pressure washers.

FAQs (Frequently Asked Questions)

Why does my pressure washer have no pressure?

You could have a pressure washer low pressure problem for a number of reasons. It could be that components are clogged and the required pressurized water flow is being restricted, or that your motor or pump is not operating effectively. The most common reasons are a damaged pump, an engine problem, or motor malfunction but, you should inspect all components to ensure they are working as they should.

How do you fix low pressure on a pressure washer?

To fix low pressure on a pressure washer you should be conducting regular maintenance to get ahead of any potential drawbacks. Try to adjust the unloader valve gradually to regulate the flow through the pressure washer and see if the pressure increases. Otherwise, you should inspect the hoses, wand, and nozzle to ensure that there are no clogged areas blocking your pressure.

How do I know if my pressure washer pump is bad?

There are several reasons as to why your pressure washer pump may be bad, with the most common being a leak caused by a worn or damaged pump seal, a pulsating output pressure due to a lack of water in the pump, and a low output pressure due to a blockage at the pump inlet or worn O-rings.

How do I get air out of my pressure washer?

To bleed the air from your pressure washer pump, you need to first turn the machine off and disconnect its high-pressure hose and wand from the machine. Now, with only the garden hose attached to the machine at the inlet, turn the water supply on and allow the water to run through the pump for around 20 to 30 seconds before turning the water off. Reconnect the high-pressure hose and trigger gun and try using the machine again.


If you have any questions about a pressure washer having no pressure, please leave a comment below, so that someone can help you!

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