One time, while cleaning my driveway with a Karcher pressure washer, I noticed the pressure started pulsing—cycling between high and low pressure. It was frustrating because the consistent flow was gone, and cleaning became inefficient. If you’re experiencing the same issue, you’re probably wondering why this is happening and how to fix it.
Keep your kids safe online with SentryPC – Monitor, filter, and control their computer use anytime, anywhere! Get started today
A pulsing pressure washer is usually caused by one of the following issues: low water supply, a blocked nozzle, air trapped in the system, a clogged water inlet filter, or a faulty unloader valve. Each of these problems can cause the machine to struggle to maintain consistent water pressure.
Here’s a breakdown of why your Karcher pressure washer is pulsing and how to troubleshoot and fix the problem.
Common Causes of a Pulsing Karcher Pressure Washer
1. Insufficient Water Supply
- Cause: The pressure washer relies on a constant supply of water. If the water flow is restricted, the pump may not be able to maintain the necessary pressure, causing the pulsing.
- Solution: Check that the water source (hose or tap) is fully open and providing enough water to the pressure washer. Ensure the hose is free from kinks or blockages that might limit water flow.
2. Blocked or Dirty Nozzle
- Cause: Dirt, debris, or mineral deposits can block the nozzle, causing a pressure buildup and uneven flow, leading to the pulsing.
- Solution:
- Turn off the pressure washer and disconnect the spray wand.
- Remove the nozzle and use a small tool like a nozzle cleaning pin or needle to clean out any blockages.
- Rinse the nozzle with water to remove any remaining dirt or debris.
- Reconnect the nozzle and test the pressure washer again.
3. Air Trapped in the System
- Cause: Air pockets in the water supply line can cause the pump to pulse as it tries to maintain pressure. This usually happens if the washer hasn’t been primed properly or there’s a leak in the hose.
- Solution:
- Disconnect the pressure washer from the water supply.
- Turn on the pressure washer without the water supply to let any trapped air escape.
- Reconnect the water supply, squeeze the trigger on the spray gun, and allow the water to flow through the system before turning the pressure washer on again. This will help prime the system.
4. Clogged Water Inlet Filter
- Cause: The water inlet filter (where the hose connects to the pressure washer) can become clogged with debris, restricting the flow of water into the machine.
- Solution:
- Turn off the pressure washer and disconnect the water supply.
- Locate the water inlet filter and remove it. It’s typically a small mesh filter that sits where the garden hose connects.
- Clean the filter under running water to remove dirt or debris.
- Reinstall the filter and reconnect the water supply.
5. Leaking or Faulty Hoses and Connections
- Cause: If there are leaks in the hoses or loose connections, air can enter the system, or water flow can become inconsistent, causing the pressure to pulse.
- Solution:
- Check all hoses and connections for leaks or loose fittings.
- Tighten any loose connections and replace any damaged or cracked hoses.
6. Faulty Unloader Valve
- Cause: The unloader valve controls the pressure inside the machine. If it’s faulty, stuck, or clogged, it can cause pressure fluctuations or pulsing.
- Solution:
- First, try cleaning the unloader valve. This may require opening the unit, so refer to your pressure washer’s manual for guidance.
- If cleaning doesn’t solve the issue, the unloader valve may need to be replaced. It’s a good idea to consult a professional if you’re unsure how to proceed with this repair.
7. Worn Pump or Internal Parts
- Cause: Over time, the pump or other internal components in the pressure washer can wear out, causing pressure fluctuations and pulsing.
- Solution:
- If none of the simpler fixes work, the issue may be with the pump or other internal parts.
- Consult the manufacturer or a professional technician to inspect the pump and replace worn components if necessary.
Quick Troubleshooting Steps
- Check the water supply: Ensure there’s enough water flowing into the pressure washer without any kinks or blockages in the hose.
- Clean the nozzle: Make sure the nozzle is clear of any debris or buildup.
- Bleed the air out of the system: Run the water through the machine without turning it on to remove any trapped air.
- Inspect hoses and connections: Look for leaks, cracks, or loose connections that might be affecting the water flow.
- Clean the water inlet filter: A clogged filter can restrict water flow and lead to pulsing.
Final Thoughts
If your Karcher pressure washer is pulsing, it’s usually due to a restricted water supply, a clogged nozzle, or trapped air in the system. Most of these issues can be easily fixed with a bit of cleaning or tightening connections. However, if the pulsing persists despite trying these troubleshooting steps, there could be an issue with the unloader valve or the pump, and you may need to consult a professional for further repairs.
Following these simple steps will help restore your pressure washer to smooth, consistent performance, making your cleaning tasks more efficient.
