Why does my pressure washer keep pulsing?

When the pressure washer pulsates, these fluctuations in the pressure system are caused either by insufficient water supply, air in the pipes or dirt. In the rarest cases it is a real defect. However, pulsing can be an indicator of other and further malfunctions.

Rarely a defect, but almost always a result of water flow

In almost all cases, pulsing in the pressure washer is caused by a harmless reason. Irregularity in the circulation system is caused by fluctuating and insufficient water supply. Of course, a technical defect in the high-pressure cleaner is also possible. However, experience shows that in the majority of cases it is due to an easily remedied irregularity in the inflow, compression and discharge of the water.

The following factors cause pulsation:

Water supply

There are several reasons why the water supply may fluctuate or reduce too temporarily. Pulsation cannot always be clearly distinguished from the stuttering of the pressure washer. If too little water is flowing, the pressure build-up also gets confused. The following mostly simple reasons can cause pulsing:

  • Water tap not turned on completely
  • Water inlet hose kinked or squeezed
  • Fluctuations in the tap water pressure (pressure limiter of the building defective)
  • Water inlet hose too thin (after extension or replacement)

Also of interest: Why does the pressure washer stutter?

Air in the pipe

Another typical trigger for a pulsating pressure washer is air in the pipe system. The simplest remedy is to remove the high-pressure hose and then put the unit into operation. If only water comes out of the connection pipe, the air has been “pumped out”. Sometimes it is enough to activate and pause the gun several times.

Also of interest: Pressure Washer Troubleshooting


Blocking dirt or dirt that obstructs the entry and exit of the water can trigger the fluctuations in the flow behaviour and the resulting pulsation. The following components should be cleaned:


The direction of a technical defect is when a pressure, non-return or suction valve is dirty or broken. If the pulsation continues after disassembly, cleaning and reinsertion and all other causes have been ruled out, a replacement must be carried out.

Almost all pressure washers are equipped with six identical valves, which are distributed over three chambers or piston passages above the swash plate and are easy to reach.

Alfred Harper

Alfred Harper

Alfred Harper is a former consultant and product expert at a company producing cleaning equipment. He was working at this position for more than 10 years and has gained incredible experience and knowledge as he has tested almost all pressure washers brands and models and became an expert in this field. Now, he is writing reviews and how-to articles about pressure washers and makes a great contribution to the Pressure Washers company to help people to choose the best cleaning equipment for home use.

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