This guide will show you exactly how to troubleshoot pressure washer problems.
- Low water pressure
- Water leaking issues
- Engine/motor turning off while in use
- And much more…
But first let me ask you a question:
You ever helped a neighbor fix something?
Be careful because once you do – and word gets around – you’ll be the go-to-fixit-guy-or-gal for everyone and everything.
Trust me, I know. All my neighbors now know me as the power equipment and pressure washer troubleshooting & tune-up guy.
Here’s what happens when you’re the neighborhood fixer:
4 pm last Saturday I’m in the shed changing pressure washer water pump oil, and over the fence my neighbor says:
“Hey, James, come fix my pressure washer and I’ll give you a beer.”
…It was an electric and started-up fine but when in-use pulsed out water to start, then after 10 seconds fell to low pressure.
My pressure washer troubleshooting experience told me it was air in the pump causing the problem. We switched off the electric motor but kept the water running through the pump. After holding the trigger to keep the water running through the machine we managed to clear the air from the pump and lines. My neighbor turned the machine on again and it worked. Full pressure, no pulsing.
Why you’ll love this beginner’s guide:
Nothing is worse than a pressure washer that starts up but won’t pressure wash properly. You get excited hearing it roar to speed but then it doesn’t properly clean your surface.
That’s why we put together this in-depth power washer troubleshooting guide for you… So you can fix the problem from your garage – even with zero experience and minimal tools.
Jump to each section:
- Summary of troubleshooting tips
- Instructions for trickier fixes
- 12 essential tools and accessories
- Hot water pressure washer repairs
- Brand specific tips and tricks
- Putting it all together
Gas and Electric Pressure Washer Troubleshooting Tips for 20 of the Most Common Pressure Washer Problems
There are 20 pressure washer issues that are by far the most common.
Here’s how we know what they are:
- Reading 300+ emails from pressure washer users asking for help to solve their machine’s issues and counting the occurrences of each fault in an Excel spreadsheet.
- Going through 16 popular pressure washer brands’ Operating Manual and tabulating the troubleshooting sections’ listed problems and solutions.
- Looking through my power washer logbooks over the last 8 years to see the most common issues.
After spending 14+ hours gathering the data the common faults could easily be broken down into 5 sections: Water pressure problems, water leaking issues, gas machine specific problems, electric pressure washer faults and other common problems. From there the troubleshooting tips are broken down to 3 columns: What’s wrong, most likely cause and how to fix.
- Always check your Operator’s Manual for troubleshooting tips and safety first. Be aware many of the problems have 5 or more possible solutions for you to try.
Summary Table of Troubleshooting Tips:
The goal of this entire page is to make the most useful pressure washer troubleshooting guide on the internet. We constantly update and improve this table. It was last updated July 11, 2020.
|What's Wrong?||Cause||How to Fix|
|1. Low pressure||Insufficient inlet water supply||Unkink garden hose, ensure full water pressure coming from tap, use large enough diameter garden hose (see manual)|
|Blocked inlet water filter||Remove garden hose connection and remove debris|
|None or incorrect nozzle||Ensure correct nozzle being used|
|2. No pressure||Damaged unloader valve||Adjust unloader screw, check for damaged seals/springs|
|Damaged pump inlet valves/manifold||Disassemble pump and replace/clean components of inlet manifold|
|3. Pulsing pressure (high then low)||Damaged pump inlet valves/manifold||Disassemble pump and replace/clean components of inlet manifold|
|Faulty pump||Replace pump|
|Pump sucking air||Turn off machine (but not water supply) and release pressure by squeezing trigger gun|
|Obstructed nozzle, water inlet filter or gun/spray wand||Use needle to clear nozzle, fresh water to flush water inlet and vinegar to clear any deposits in gun/wand|
|4. Spiking pressure||Poorly calibrated unloader valve||Adjust unloader to proper pressure as per manual|
|5. Pressure drops after a few seconds use||Nozzle blocked||Clear nozzle with needle|
|Issues with unloader valve||Remove unloader and clean/repair|
|6. Pressure washer isn't cleaning the surface||Using wrong nozzle||Switch to higher pressure spray nozzle|
|What's Wrong?||Cause||How to Fix|
|7. Water leaking from pump||Seals broken, cracked or worn||Return and replace under warranty|
|Loose bolts on pump assembly||Tighten bolts to ensure pump casing properly sealed together|
|Thermal valve activated||Wait 5 minutes before using (it will de-activate once cool enough)|
|8. Water leaking from garden hose connection||Broken or improper connection||Connect properly|
|Broken rubber washer||Replace|
|9. Water leaking from spray wand or connections||Broken o-ring inside hose connection||Replace o-ring or return hose for new|
|Not properly connected||Connect properly|
|What's Wrong?||Cause||How to Fix|
|10. Engine will not start||No gas||Fill with gas|
|Choke is wrong position||Move to correct position as per manual|
|Pressure build up||Squeeze trigger gun to release pressure in system|
|Spark plug wire not connected||Connect wire|
|Faulty spark plug||Replace with new|
|11. Engine stops running while in use||Low oil level||Check and fill oil|
|Dirty air filter||Clean or replace it|
|12. Engine not providing enough power||Dirty air filter||Clean or replace|
|Engine not running at correct RPM||Adjust RPM to engine specs with pump detached|
|13. Oil dripping from engine||Worn seals||Replace seals (covered by warranty)|
|14. Water in oil - looks milky||Worn or broken pistons allowing water through||Repair engine through warranty|
|Worn seals||Replace seals (covered by warranty)|
|What's Wrong?||Cause||How to Fix|
|15. Machine won't start||Electric outlet is faulty||Check main fuse, check plug|
|Not plugged in||Plug in|
|Faulty motor||Return under warranty|
|16. Motor stops running while in use||Low voltage||Check voltage is within motor specified range|
|What's Wrong?||Cause||How to Fix|
|17. Chemical/detergent injector not working||Using wrong nozzle||Insert black soaping nozzle on wand|
|Soap tube inlet filter clogged (hose end that sits in soap bottle)||Flush with fresh water|
|Soap inlet valve is clogged or blocked (pump side of tube)||Remove hose and use small Allen key to push through hole to remove debris/unstick the ball valve|
|Detergent mixture is too thick||Add more water to dilute|
|18. Irregular bypass causing pressure fluctuations (sometimes) after use||Worn or broken unloader valve seals, springs or other components||Remove and replace|
|Unloader valve not properly installed||Remove and install correctly, properly seating the valve at the bottom of the pump housing|
|Water leaking from unloader valve||Replace worn or broken seals and re-install unloader valve to specification|
|Dirt in unloader||Remove and clean|
|19. Excessive noise||Water intake is blocked||Check and clean or replace|
|Not enough oil in engine||Check and add oil|
|Not enough oil in pump||Disassemble and check (if possible) and add oil, otherwise return under warranty|
|20. Oil leaking from pump||Loose bolts/fitting||Check and tighten|
|Damaged parts like seals or pistons||If comfortable disassemble to check, clean and replace, otherwise return under warranty|
Instructions How To Correct The Tricky Issues
In this section are instructions how to fix the tricky pressure washer issues, namely the ones that require you to tear down the pump.
The Lazy Man’s Way to Diagnose Water Pressure (No Pressure) Issues
Here’s the 5 step approach to solving 95% of water pressure issues in 10 minutes or less:
- Check water supply: Open the water supply valve to full to ensure the pump is getting enough flow.
- Check hose for kinks: I can’t tell you how many times I’ve tested a pressure washer, got everything going, only to pull the trigger have it not reach pressure. I check the inlet for blocks. I check the nozzle. I check the water is on. And after all these things check out and it’s still not working I turn it off to read through the manual to find out what I’m doing wrong. Then, all of sudden, I notice a kink in the hose and realize how much an idiot I was not to notice. I fix the kink start the machine and it all works fine. Don’t make this mistake – always check for kinks.
- Release air from system: Always connect the garden hose to the power washer first. Then turn the water tap on and pull the trigger gun to release water from the system at the garden hose water pressure before starting the engine or motor. This will release all the pressure from the system and allow the pump to function.
- Ensure correct nozzle and nozzle not clogged:
Use a needle to clear the nozzle tip of any debris. Any blocks at the nozzle will cause decreased flow and increased pressure in the systems, possibly triggering the unloader to enter bypass.
Everything You Need to Know About Removing the Unloader Valve to Check for Issues
Unloader valves allow water to run through the pump when you are not holding down the trigger on the pressure gun. If there was no unloader valve then pressure would build inside the system (when not in use) so when you did pull the trigger it would stall the engine or explode a weak link part – probably the pressure hose o-ring.
Check out where the unloader is located on 3 different pressure washer pumps:
As you can see the unloader is located on the exit side of the pump because it allows the pressurized water to flow back through the pump when it isn’t exiting into the high pressure hose (you’re not pressure washing anything).
Take a look at two different disassembled unloader valve assemblies:
The unloader on the right is from an AR Blue Clean electric pressure washer. It is a pressure actuated unloader.
Both these assemblies can be taken out of the pump for cleaning and repair, without damaging them.
The Difference Between Flow and Pressure Actuated Unloaders
- Flow actuated – As the name suggests, these unloader valves respond to water flow stoppage. When there is no flow leaving the nozzle the valve will “open” allowing water to flow back to the pump inlet.
- Pros: Safer because doesn’t require pressure build up.
- Cons: More sensitive to system issues like a clogged nozzle, incorrect nozzle orifice size and other flow problems.
- Pressure actuated – Instead of responding to flow, this type of unloader is forced open by an increase in water pressure allowing water to bypass back to pump inlet (this pressure is increase is usually caused by flow stoppage).
- Pros: Less sensitive to flow issues within the system because it responds only to trapped pressure on the outlet side of the pump.
- Cons: Less safe because it needs pressure rise to work (could cause failures within system).
Troubleshooting the Unloader Valve
Many pressure problems begin and end at the unloader. A cracked o-ring, dirt caught in the spring or a stuck shaft are the most common issues solved by simply removing the unloader and cleaning/looking for issues.
12 Essential Tools and Accessories
The 12 below tools are the most commonly used to repair pressure washers.
Using the below tools I’ve fully disassembled (all the way down to removing the gas engine piston seals and crankshaft) and put back together: 3 electric pressure washers and 4 gas power washers. Let’s run through the tools, where they are used and if you should buy a complete tool kit or individual tools (and from what tool brands) for repairing your pressure cleaner.
These are one of the most used tools troubleshooting pressure cleaners because most pump assemblies are fastened together with hex head screws. They are often called Allen head after the company Allen Manufacturing that started mass producing hex screws and hex wrenches (Allen wrenches/keys) to fasten them in the early 1900s.
There are 3 main advantages to hex head screws:
- Recessed head to make screw durable and unlikely to damage.
- Use same hex head on different screw types, sizes and threads (thus only one hex key tool required). These would require several different wrenches if they didn’t have hex head. This is likely the reason behind their common use on bicycles – one hex key pocket-size set can help you disassemble and repair your entire bike (many different screw sizes and types but if they all have hex head you only need your hex keys).
- Torque wrench can be used to tighten them to exact design specification.
Needle-nose pliers are very handy because they reach small areas to remove o-rings, seals and valves. I use them often when tearing down a pump to fix water pressure issues. I also use them when putting it back together to seat valves and get o-rings and seals into position.
You’ll be very happy to have a set lying around when trying to sort out your power washer faults.
I had a hard time deciding to put hex keys or needle-nose pliers first because they are both used often.
Almost the only tool you need to disassemble electric pressure washers is a screwdriver.
Electric machines’ plastic covers – which hide the pump and motor – are held together with Philips head screws.
Gas machines also use Philips – often to clamp down wires and assemble their frames etc.
In addition, you’ll want some slotted screwdrivers to help wedge/drive out certain parts like pump plunger seals. Torx head screws are also used once you get to the engine block.
Sockets & Ratchet
Every tool set needs sockets & ratchet and wrenches despite them doing the same thing.
Because you can have one ratchet and socket heads for every bolt size in a compact case. The ratchet allows you to remove or tighten bolts without repositioning and deep socket attachments allow reach to tight spots.
However, you also need wrenches, especially the open-end side to get to bolts from the side when the top isn’t in reach.
Wrenches have been in use since the 15th century and are probably the most well-known and owned hand tool.
Many prefer to use a ratchet-socket combination because it is quick (don’t have to reposition tool when tightening or loosening fastener) and it’s easier to store (and carry around) 50+ socket heads instead of 50+ wrenches.
But: When you need to get to screws in tight spots you need a wrench. And pressure washers have some tight spots.
Rubber Mallet or Hammer
Did you know hammers are the oldest known hand tool?
Yup, hammers with handle attached to hard impacting head have been discovered and dated back 30,000 years. And nearly exact replicas of the modern hammer have been found and dated to around 5,000 BC.
They have been useful to humans for 1000s of years – a pretty cool tool.
While troubleshooting pressure cleaners they are used to free stubborn parts like the pump head valve plate.
Cutting tools like knives have been in use nearly as long as hammers.
They are great help to troubleshoot faults because they make quick work removing the detergent hose and help wedge under tight fitting components to loosen them. Cutting the soap hose is fine because there’s lots of it and you’ll probably damage it using pliers or other means, anyways.
In addition, you probably own several knives already so no need to go out buying any just to help solve pressure washer issues.
I like using snips instead of a knife because it’s more precise and quicker.
My snips are sheet-metal snips and cut through tree branches, hoses, and thick plastic or rubber without issue. So if you burst a pressure washer hose, you could cut it shorter (with snips) and install the fitting instead of buying brand new. We did this all the time at a job I had as a 19 year old using a pressure washer to clean a factory parking lot and truck scale every-single-morning.
Snips are a must-own.
There’s no need to go into detail about these accessories. You will 100% want to have silicone grease when you reinstall o-rings, and WD-40, thread tape and grease cleaner will be useful, no doubt.
What’s the Best Tool Set to Get?
The single kit that has everything you need to troubleshoot pressure cleaners (except for a rubber mallet) is this 170-piece mechanics tool set by Crescent.
You can see that it has:
- Hex keys
- Ratchet + sockets,
- Snips built in to the needle-nose pliers, and
- Carry case.
If you don’t already own all these hand tools – and you plan on fixing your power washer on your own – then this is the best tool kit.
Troubleshooting Hot Water Power Washers
Hot water pressure washers can suffer 3 faults:
- No hot water produced
- Too much/weird color smoke out the burner
- No flame from blower.
There’s 15 or so reasons why you may experience these faults and the same number of fixes.
Before we get into the fixes, let’s learn more about the burner components.
How a Pressure Washer Burner Works
A hot water pressure washer has a burner to heat the water. The burner uses diesel or kerosene & air + electricity to generate a fire inside a chamber with water circulating around the exterior in tubes coiled like a snake. Water enters at the bottom and by the time it reaches the top – having circulated through all the coil around the flame – exits at the top as hot water.
The burner adds risk/danger to troubleshooting because of the, well, fire. We recommend you take it to a pressure washer repair centre to get fixed. However, there are some simple fixes.
What parts does a pressure washer burner have?
- Steel tubing/coil
- Fuel pump/motor and fuel spray nozzle
- Blower motor
- Electrodes/ignition tranformer
- Flow switch
- Pressure release valve
- Air adjustment slider
- Fuel filter
Here’s a 9-minute video to explain everything on burner troubleshooting:
Brand Specific Tips & Tricks for Diagnosing and Fixing Power Washer Issues
Let’s look at popular brands, the types/styles of pressure washer they make (including pump brand & type), common issues with those pumps and where you can find further troubleshooting information.
Troy Bilt Troubleshooting Resources
Briggs & Stratton is Troy Bilt’s OEM (original equipment manufacturer) meaning Troy Bilt specifies certain things about the machine (eg. Honda or Briggs engine) and Briggs makes them in their factories. The Troy Bilt sticker is then placed on the power washer for sale.
A common fault is that your Troy Bilt will experience no pressure or low water pressure when you start washing. This is often caused by a dirty or broken unloader valve assembly (see above tips).
Further information: Troy Bilt Support Center
Generac makes and sells residential-use medium and heavy-duty machines as well as belt driven units for commercial use. They have an OEM overseas to manufacture their pumps and engines then assemble them back in their factories in the USA.
Further information: Generac Pressure Washer Support Product Lookup
Karcher makes all types/styles of pressure washers through their own brand and subsidiary brands including Hotsy, Shark and Landa. They are easily the biggest pressure washer maker and seller in the world. They makes models with all types of the best small engines and pumps and have an extensive rental and service network through their subsidiary brands.
Further information: Karcher Pressure Cleaner Knowledgebase
Simpson Cleaning sells home and commercial use machines with Kohler, Honda and Simpson OHV engines. The pump brands they use are two in-house brands: OEM Technologies (axial cam) and AAA Pumps (triplex). They also use CAT Pumps brand on some of their premium residential and commercial machines.
Simpson Cleaning are some of the most popular residential gas machines because they offer great value for money and their pressure washers’ wheelbarrow stance is sturdy and much easier to move around compared to the common upright designs.
Common problems include low or no pressure after a few seconds use and soap not entering system properly.
Further information: Simpson Support Page
If you pressure wash you’re bound to need to troubleshoot an issue at some stage. Whether it be no water pressure because of a hose kink or low pressure because of a busted o-ring inside the unloader…
…it will happen eventually – but since you made it this far you will have the knowledge to sort your problem out from your garage – with minimal tools and time.
To decrease the risk of having major issues, take a look at the 7 best for home use – these are the best designed and least likely to fail.
Okay, to wrap up: Let’s review the gist of the tips outlined in this guide:
- Water pressure issues (no, low and/or sporadic water pressures): Check water supply is on full and no hose kinks. Check inlet filter isn’t clogged. Check nozzle isn’t blocked. Turn off engine/motor (but keep water on) and pull trigger to release air from system. If none of this works, it may be the unload valve being stuck due to dirt or broken parts. See unloader section above.
- Water leaking from connections: First ensure connections are securely fitted. If water is squirting out while pressure washing it is most likely a busted o-ring inside the the pressure hose. Contact support and get them to send new o-ring or hose.
- “Troubleshooting Pressure Washer and Power Washer Problems.” www.PressureWasherTroubleShooter.com
- “Hammer History.” Wikipedia.org
- “All About Unloader Valves.” www.ePowerWash.com
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.