There could be several things causing your pressure washer to lose pressure. Before you take it to the repair shop or buy a new one, avoid the hassle and check your pressure washer with this list in mind. Here’s a step by step walkthrough of some common problems we’ve seen from DIY power washer users when troubleshooting loss of pressure issues.
Check for leaks
There could be small leaks, holes, or tears in your garden hose or high-pressure hose that are causing your pressure washer to lose pressure when you pull the trigger. If you find leaks, plug the holes or replace the hose, which should solve your pressure issues. If there are no leaks, this is also a good step to check for any kinks in the line which could be stalling water flow.
Check the water source and water flow
If your water supply flow is lower than the GPM on your pressure washing unit, it could be causing your pressure washer to lose pressure. GPM is the gallons per minute that your pressure washer uses to function correctly. The flow of water from your hose should produce the same amount or more GPM’s as needed for your pressure washer. If these don’t match up, it could be the cause of your low pressure.
Check for a blockage in the nozzle tip
Pressure washer nozzles can get blocked fairly quickly. There are two ways to check if you have a clogged nozzle:
- Test Out Nozzles: Hook up your pressure washer like normal, but don’t start the engine. If there is a steady stream of water coming out of the nozzle, move on to the next tip. However, if no water or very little water is coming out of the tip, there may be an issue.
- Check for blockage: Remove the nozzle and shine a flashlight through the nozzle tip. If there is an obstruction, you won’t see the light at the opposite end of the hole. Grab a small tool like a toothpick or twist tie wire and dig out the clog. If you have an air compressor, you can use the air compressor to remove the blockage.
Is the right nozzle tip on?
New owners might have the wrong nozzle tip on their pressure gun. Check to make sure that you did not screw on the soap injector tip. The soap injector tip is meant to be a low-pressure tip to distribute chemicals, soap, and other materials. Simply change the tip out with one of your other tips; if you had the soap injector tip on, the pressure will improve dramatically once it is replaced with the correct nozzle.
Replace the nozzle tip
Many pressure washer owners have a favorite nozzle tip that they use all the time. Frequent use causes the nozzle to wear out. The best way to check if the nozzle is worn out is by switching the nozzle tip out for one you use the least. You’ll be able to tell right away if the nozzle tip is worn out.
Low pressure can also result from O-ring problems. There are two places to check for issues:
- The outlet coupler: First, unscrew the outlet coupler; a small spring and plunger will pop out. Look to see if there is an O-ring around the plunger; if there isn’t, it’s probably lodged in your outlet coupler. Remove the old O-ring from your outlet coupler and head to the hardware store for a new one.
- The pressure washer wand: The O-ring in a pressure washer spray gun can rust or become damaged. Replacing the o-ring in your wand could solve your flow rate problems.
Check your unloader valve
Your unloader valve is the big red or black knob on your pressure washer. Make sure it’s cranked to full pressure. Sometimes, new pressure washer owners will have the knob set to low pressure, which causes low pressure issues.
Generally you will find the unloader above the water inlet.
Check the Unloader Valve Spring
There is a valve spring located inside the unloader that can get rusty. If there is a lot of rust on the spring, it is probably affecting your pressure washer’s pressure. Replace the spring, and you should see the pressure return to normal.
Check the Pressure Washer Spray Gun
New pressure washing machine owners sometimes forget to add a nozzle to their wand. If you’re experiencing garden hose pressure when you pull your handle, you might have forgotten to add a nozzle. Add a nozzle, and you should see the pressure increase exponentially.
The Water is Too Hot or Too Cold
Check to see if your pressure wash is a cold water or hot water pressure washer. If your pressure washer is cold water only, using warm water could mess with the pressure. Try replacing the water you’re using if it’s been out in the sun all day. If your pressure washer is a hot water pressure washer, make sure your water temperature is correct based on the manufacturer’s specifications.
Check The Oil
Like a car, if a pressure washer is low on oil, it doesn’t work well. Replace or add oil to your pressure washer, and you should see an increase in pressure. This tip only applies for gas models, not electric pressure washer models (duh, because those don’t need oil).
Pressure Washer Pump Problems
If you’re still experiencing problems, it’s time to check your pump. Hook a garden hose up to your pressure washer and pull the handle. You should see some increase in pressure by doing this. If you don’t, then you have a pump problem. It’s an easy fix, just check the filter and clean your pressure pump. We have a great guide to pump cleaning here. [link to pressurewashr.com article about pump cleaning]
Another common cause of low water pressure is belt slippage. If you have a belt drive pressure washer, the belt could have shaken loose or needs to be replaced all together. First, try tightening the pressure washing belt; if that doesn’t work, then you’ll likely need to head to a hardware store or call a pressure washing mechanic to get a new belt installed.
Air in your Pressure Washer
The only air flowing through your pressure washer should come through the air filter. If air is getting in through another way other than the air filter, then that could mess with your water pressure. Check the hoses and pipelines to make sure they are fitted correctly and tightened all the way.
Replace the gasoline
Gasoline older than three months could cause issues with your pressure washer. Replace the gas and see if that increases your pressure amount.
If you make it to the end of this list and you’re still experiencing low-pressure output, it may be time to call in the experts. If this is a new pressure washer, it may still be covered under warranty.
Jamey has been testing and reviewing top pressure washers for 7 years. He worked as a commercial pressure washer at a rendering plant for 3 years and all up has been using commercial and residential pressure washers for 15+ years. He is also a mechanical engineer and while working in the mining industry designed several turn-key light industrial vehicle wash pads.