Other outdoor power

Pressure washer has low pressure

Weak spray from a pressure washer is usually caused by a partially clogged nozzle, a worn unloader valve, or air trapped in the pump or hose.

Difficulty
Easy
Time
15–30 minutes
DIY cost
$10–$40
Pro cost
$80–$180

Symptoms

  • Spray is weak or dribbles instead of a strong jet
  • Pressure fluctuates while spraying
  • Engine or motor runs fine but output is weak
  • Pressure was fine last use and dropped suddenly

Likely causes

  • CommonClogged or worn spray nozzleDebris in the tip or nozzle wear reduces pressure and spray pattern.
  • CommonAir trapped in the systemAir pockets after a hose change or new pump cause pulsing, weak spray.
  • PossibleWorn unloader valveThis valve regulates pressure and can wear or stick over time.
  • PossibleKinked or damaged high-pressure hoseA kink or internal damage restricts flow.
  • PossibleInsufficient water supplyA partially closed spigot or garden hose that's too thin starves the pump.

What to do

  1. Make sure the water supply hose is fully open and not kinked, and that it's at least 5/8 inch diameter.
  2. Turn off the machine and clean the spray nozzle tip with the cleaning pin that often comes with the unit.
  3. Purge air by running the washer without the nozzle attached until water flows steadily.
  4. Inspect the high-pressure hose for kinks, cracks, or bulges.
  5. Check the inlet water filter screen for debris and clean it.
  6. Try a different nozzle tip to rule out a worn or damaged one.
  7. If pressure stays low, the unloader valve or pump may need professional service.

Tools and parts

  • Nozzle cleaning pin
  • Garden hose
Pressure washer nozzle tip setSearch: “pressure washer nozzle tips replacement”
Pressure washer hoseSearch: “pressure washer high pressure hose replacement”

When to call a pro

If cleaning the nozzle and hose doesn't restore pressure, a pressure washer repair shop can test and replace the unloader valve or pump.

Safety

Generally low risk

Generally low risk for a careful person. Stop if anything looks different from what this guide describes.

Related guides

Operator provides AI-generated troubleshooting information. It can be wrong. For safety-critical, electrical, gas, structural, medical, automotive safety, or other high-risk problems, consult a qualified professional.