A pressure washer that loses pressure while running usually has a partially clogged nozzle or inlet screen, a worn or damaged pump seal or unloader valve, or an engine that’s losing power under load. Air entering the water supply line can also cause intermittent pressure loss. Doc Wally’s services pressure washers in the New Braunfels area and can diagnose the problem at your location.
Key Takeaways
- A clogged nozzle or inlet filter is the easiest fix and the first thing to check
- A failing unloader valve causes pressure to fluctuate or drop suddenly
- Pump seal wear causes gradual pressure loss that gets worse over time
- Insufficient water supply (low GPM at the source) can starve the pump
- A mobile diagnosis identifies the real cause before you replace parts you don’t need
Nozzle and Inlet Screen
Start with the simplest things. A partially clogged spray nozzle restricts flow and drops pressure at the gun. Remove the nozzle and rinse it or use the thin wire tool that came with your machine to clear the tip opening. The inlet screen (the filter at the garden hose connection) can also clog with mineral deposits or debris and should be cleaned regularly.
The Unloader Valve
The unloader valve is a pressure-relief component that redirects water flow when you release the trigger. When it starts to wear or its spring loses tension, it can fail to fully close when you squeeze the trigger again, causing pressure to drop intermittently or not build back up properly. Unloader valve replacement is a common repair on older pressure washers and not especially expensive.
Pump Seal Wear
Pump seals keep water pressurized inside the pump head. As they wear, water bypasses internally and output pressure drops. You may also see water weeping from the pump body around the seal area. This is a normal wear item on higher-hour machines.
Water Supply
A pressure washer pump needs a consistent water supply at adequate flow. Running with a kinked hose, a partially closed valve, or a source that doesn’t provide enough GPM will cause pressure to surge and drop. The pump is cavitating — trying to compress water that isn’t fully there — which also causes damage over time.
Call Doc Wally’s
Pressure washer repairs done wrong can cause further pump damage. Doc Wally’s comes to your property in the New Braunfels area, diagnoses the pressure issue, and makes the repair. Call to schedule a mobile visit.
People Also Asked
Q: How often should pressure washer pump oil be changed?
Every season or every 50 hours of use for pump-oil-lubricated models. Many residential pressure washers have sealed pumps that don’t require oil changes.
Q: Can I run my pressure washer without water connected?
No. Running a pressure washer dry — even for a few seconds — will damage the pump seals quickly. Always ensure water is flowing before starting the engine.
Q: What causes a pressure washer pump to make a loud rattling sound?
Rattling often indicates cavitation (insufficient water supply), debris in the pump, or a failing check valve. Stop use and have it inspected.