Guide · Nozzle tips and turbo nozzles
Low or pulsing pressure: nozzles, inlet filter and supply first
Cat Pumps names worn nozzles as the most frequent cause of low pressure. What to check first (nozzle, water supply, inlet filter) and when to stop and call the maker.
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Short answer
Start with the nozzle. Cat Pumps names worn nozzles as the most frequent cause of low pressure, and the fix is to replace them with the proper size. Then check the water supply and the inlet filter. Never adjust the pump's pressure regulating valve to make up for a worn nozzle, and take leaking seals or pump problems to the maker's service.
1. The nozzle
Cat Pumps' troubleshooting guide says worn nozzles are the most frequent cause of low pressure, and that the fix is to replace them with the proper size.[2] A worn orifice is larger than it was, so the same flow builds less pressure through it. The nozzle size chart shows how much a size change moves the numbers.
Check the stamp on the tip you are using. If it is not the size your machine's maker supplied, that alone can explain the drop. Which nozzle size fits your machine shows how to work it out.
Cat Pumps also warns never to adjust the pressure regulating valve to compensate for worn nozzles, because doing so can over-pressurize and damage the pump.[2] The same goes for any pump valve, whatever your manual calls it: we do not give adjustment steps.
2. Pulsing: a clogged or restricted nozzle
Generac's manual says a pulsing felt when squeezing the trigger may come from excessive pump pressure, typically caused by a clogged or restricted nozzle.[3] It gives a nozzle-cleaning procedure that starts with the engine and water off and the pressure relieved. Follow your own maker's procedure from the manual rather than improvising one.
Kärcher's FAQ, for its residential machines, says to clean the nozzle insert and check the nozzle when the spray sputters.[4]
3. The water supply
A pressure washer can only push the water it gets. Makers set supply minimums.
- Champion's 100384 manual lists a restricted water supply, a garden hose that is too small, a clogged inlet filter and an obstructed nozzle as causes of low or fluctuating pressure. It recommends a 5/8 in or larger garden hose and at least 10 ft of unrestricted hose between the washer intake and the faucet.[1]
- Generac's manual for its gas power washer line requires a water supply below 100°F, a supply hose no longer than 50 ft, and at least 3.8 GPM at no less than 30 PSI.[3]
- Sun Joe's SPX3000 manual limits inlet water to 104°F and says the machine must never be connected to a hot water supply.[5]
These figures belong to those makers' machines. Your manual has its own.
4. The inlet filter and the accessories
For a Kärcher machine with no pressure, Kärcher's FAQ lists owner checks including removing and cleaning the water-inlet filter and checking that the right accessories are being used.[4] An accessory meant for another machine, such as a nozzle of the wrong size, can look like a fault.
The water inlet fittings guide covers the garden-hose end of the connection.
Quick checklist
| Symptom | Check first | Source |
|---|---|---|
| Low pressure on every tip | Worn or wrong-size nozzle | Cat Pumps[2] |
| Pulsing at the trigger | Clogged or restricted nozzle | Generac[3] |
| Low or fluctuating pressure | Supply hose size, faucet flow, inlet filter | Champion[1] |
| No pressure (Kärcher) | Inlet filter, the right accessories | Kärcher[4] |
When to stop
Kärcher refers leaking seals to a service partner.[4] If a new nozzle of the right size, a clean filter and a good supply do not fix it, the problem is likely inside the machine. Stop there and contact the maker's service center. We do not cover pump or engine repair.
Replacement tips
Picks that fit3 products
Replace worn tips with the same size your machine uses. SIMPSON 80145 is the size 3.0 set; SIMPSON 80146 and DEWALT DXPA45ST are size 4.0 sets, for higher-flow gas machines.
More on choosing
If your machine uses another size, buy the maker's own replacement tips. On Amazon, check that Ships from / Sold by is Amazon.com or the brand.
SIMPSON five-tip set, smaller of two sizes
SIMPSON 80145 1/4 in quick-connect nozzle set, 5 tips, size 3.0, 3,600 PSI
SIMPSON five-tip set, larger of two sizes
SIMPSON 80146 1/4 in quick-connect nozzle set, 5 tips, size 4.0, 4,500 PSI
Five-tip set in size 4.0
DEWALT DXPA45ST 4,500 PSI quick-connect spray tips, 5 tips, size 4.0, stainless steel
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Questions
Why did my pressure washer lose pressure?
Cat Pumps names worn nozzles as the most frequent cause of low pressure. Champion's manual also lists a restricted water supply, a garden hose that is too small, a clogged inlet filter and an obstructed nozzle.[2][1]
Why does my pressure washer pulse?
Generac's manual says a pulsing felt when squeezing the trigger may come from excessive pump pressure, typically caused by a clogged or restricted nozzle, and gives a nozzle-cleaning procedure. Champion lists fluctuating pressure under supply problems too.[3][1]
Can I turn up the unloader to get my pressure back?
No. Cat Pumps warns never to adjust the pressure regulating valve to compensate for worn nozzles, because it can over-pressurize and damage the pump. Replace the nozzle with the proper size.[2]