Pressure washers & generators

Pressure washer has low pressure

Weak spray is most often a partially clogged nozzle, a worn or wrong-size nozzle tip, or the unloader valve not building full pressure; a worn pump comes last on the list.

Difficulty
Easy
Time
15–30 minutes
DIY cost
$0–$20
Pro cost
$80–$180

Symptoms

  • Water comes out but with little force
  • Pressure was fine before and has gradually dropped
  • Spray pattern looks like a garden hose, not a jet
  • Pressure drops further the longer it runs

Likely causes

  • CommonPartially clogged spray nozzleDirt or mineral debris narrows the tip opening and lets pressure bleed off instead of focusing it.
  • CommonWrong or worn nozzle tipA worn tip has an enlarged orifice that can't build the pressure it used to.
  • CommonInlet water restriction or kinked hoseThe pump can only push out as much water as it's fed; low inlet flow caps output pressure.
  • PossibleUnloader valve misadjusted or stuckThis valve controls how much pressure bypasses back to the inlet; if it's stuck open, pressure never builds fully.
  • PossibleWorn pump seals or valvesInternal wear lets water bypass instead of being pressurized, common on older units with heavy use.

What to do

  1. Check the garden hose supply for kinks and make sure the spigot is fully open; low inlet flow directly limits output pressure.
  2. Remove the nozzle tip and use a small wire or the cleaning pin that came with the unit to clear the orifice of debris.
  3. Inspect the nozzle for an enlarged or oval-shaped opening, which means it's worn and should be replaced.
  4. Check the inlet water filter screen (where the hose connects) and clean or replace it if clogged.
  5. Try a different nozzle tip, starting with a lower-degree (more concentrated) spray pattern, to see if pressure improves.
  6. If pressure still seems low, check for kinks or leaks along the high-pressure hose itself.
  7. If none of this helps, the unloader valve or pump internals may need service; this is a good point to consult a pro if you're not comfortable disassembling the pump.

Tools and parts

  • Nozzle cleaning pin
  • Small wire
  • Replacement nozzle tips
Pressure washer nozzle tip setSearch: “pressure washer quick connect nozzle tips”
Inlet water filter screenSearch: “pressure washer inlet filter screen”

When to call a pro

If pressure is low even with a clean, correct nozzle and full water supply, a small-engine or power-equipment shop can test the pump and unloader valve.

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.