Pressure Washer Troubleshooting Guide
Pressure washers are extremely reliable machines when maintained properly, but even the best equipment can run into issues. This troubleshooting guide covers the most common pressure washer problems contractors and homeowners experience, along with the most likely causes and solutions.
Need a faster diagnosis? Use PSupp, the Rockstandard pressure-washer diagnostic app, to work through symptoms involving pumps, engines, burners, unloaders, flow problems, and more. You can also see all Rockstandard Apps.
1. Why Is My Pressure Washer Pulsating or Surging?
A pressure washer that pulses or surges typically indicates a restriction in water flow or a problem with the pump’s pressure regulation system.
Common causes:
- Clogged spray nozzle
- Insufficient water supply
- Air entering the inlet hose
- Worn or sticking unloader valve
- Clogged inlet filter
What to check:
- Remove and clean the spray nozzle.
- Verify the water source can supply enough flow.
- Inspect the inlet screen for debris.
- Check the unloader valve for proper operation.
2. Pressure Washer Has Low Pressure
Low pressure is one of the most common issues seen with pressure washers and can usually be traced to a few key components.
Possible causes:
- Incorrect nozzle size
- Worn pump valves or seals
- Unloader valve set too low
- Partially clogged nozzle
- Water supply restriction
Troubleshooting steps:
- Verify the nozzle size is correct for your machine’s PSI and GPM.
- Clean or replace the spray nozzle.
- Check the inlet hose and filter for restrictions.
- Inspect pump valves and seals if pressure remains low.
3. Pressure Washer Runs But Has No Pressure
If the engine or motor runs but there is little to no pressure, the problem usually involves the pump or unloader system.
Possible causes:
- Broken pump valves
- Severely worn pump seals
- Unloader stuck open
- Incorrect nozzle installed
Recommended checks:
- Inspect and replace damaged pump valves.
- Verify the unloader valve is functioning correctly.
- Make sure the spray nozzle is installed.
4. Pressure Washer Loses Pressure When Trigger Is Pulled
If pressure drops significantly when the spray gun trigger is pulled, the machine may be starving for water or the pump may be experiencing cavitation.
Common causes:
- Insufficient water flow to the pump
- Collapsed inlet hose
- Clogged inlet filter
- Air leaks in water supply
Solution:
- Ensure the water source provides adequate flow.
- Use a larger diameter supply hose if necessary.
- Inspect hose connections for air leaks.
Still not finding the cause? Run the symptoms through PSupp →
5. Pressure Washer Soap Injector Not Working
Soap injectors rely on low pressure to draw chemical into the water stream. If your injector is not pulling soap, the issue is often related to pressure or injector blockage.
Common causes:
- Using a high pressure nozzle
- Clogged injector
- Chemical pickup hose blocked
- Injector ball stuck closed
Troubleshooting:
- Switch to a low-pressure soap nozzle.
- Clean the injector using warm water or compressed air.
- Inspect the chemical pickup tube and filter.
6. Pressure Washer Engine Bogging Down Under Load
When an engine struggles under load, it usually means the pressure washer is demanding more power than the engine can deliver.
Possible causes:
- Unloader valve set too high
- Incorrect nozzle size
- Engine fuel delivery issue
- Restricted exhaust or air filter
Steps to resolve:
- Verify nozzle size matches the machine’s rating.
- Adjust the unloader valve to proper pressure.
- Inspect fuel and air filters.
7. Hot Water Pressure Washer Producing Smoke
Smoke from a hot water burner usually indicates incomplete combustion or excess fuel.
Common causes:
- Improper fuel pressure
- Dirty burner nozzle
- Restricted air intake
- Improper electrode gap
Recommended checks:
- Inspect and clean the burner nozzle.
- Check electrode positioning and gap.
- Verify fuel pump pressure.
Still Need Help Diagnosing the Problem?
Open PSupp and start a pressure-washer diagnosis →
PSupp is the Rockstandard diagnostic app built to analyze symptoms and guide you through the repair process step by step. For additional tools, visit Rockstandard Apps.
If you need parts, service, or expert advice, contact Rockhold Ranch Equipment. We specialize in commercial pressure washer repair, parts, and equipment for professionals.