How to fix a pressure washer pump

The most common malfunction: pressure build-up error

If your pressure washer does not work, it is usually due to a pressure build-up fault. Without sufficient pressure, the device cannot force the water out of the tank through the hose and pipe. Fortunately, you can repair a pressure washer even without expert knowledge – with a little skill and the right tips.

A pressure buildup error can have several causes. Among others, these can be:

A clogged water filter: dirt makes the filter impermeable, it should be cleaned or replaced if necessary.
A defective pump impeller: If the pump is defective or individual valves are clogged or damaged, this will lead to faults in pressure build-up.

A fault in the high-pressure set: The high-pressure set may be leaking or clogged. Both hinder the pressure build-up.

Defective valves and seals: Leaky or dirty valves and seals limit the functionality of your pressure washer.
Air in the supply hose: If there is air in the supply hose, your pressure washer cannot draw water or cannot draw enough water.

Air in the pressure washer: Air in the pressure washer causes bubbles to form in the water, which weakens the water jet.

Too long or clogged water hose: If the water hose is too long, your pressure washer needs too much energy to draw water. Blockages caused by dirt in the hose also cause poor pressure.

Too little water: A pressure washer can usually only build up enough pressure when the water tap is turned on fully. How much water your device needs can be found in the operating instructions.

How to repair your pressure washer

You can repair most of the causes of a pressure build-up fault in your pressure washer yourself. Important: You should always disconnect the device from the power supply first! In addition, always follow the manufacturer’s instructions in the operating manual of your device.

In the following, we will explain how you can repair your pressure washer. Note: The instructions are general, as the procedure may vary from model to model.

If the cause is not obvious at first glance, you should check the individual possible sources of error one after the other. After each error option, test whether your pressure washer is working properly again.

This is how it works:

  1. Make sure that the water tap to which your pressure washer is connected is turned on fully.
    Check your water hose for damage and knots.
  2. Is the water hose clogged or too long? Clean it or shorten it if necessary. The hose should never be longer than 30 meters.
  3. To rule out air in the supply hose, disconnect the hose from your pressure washer – if you haven’t already done so – and turn on the water.
  4. As soon as the water comes out of the front of the hose without bubbles, you can reconnect it.
    Is there too much air in the pressure washer itself? Hold the trigger down for a few minutes to let it escape.
  5. Is the pressure washer clogged or damaged? Blockages caused by dirt or limescale, for example, can be removed carefully with a needle.
  6. If cleaning does not help, you should replace the high-pressure set.
  7. Unscrew the water filter from its holder and carefully remove any dirt.
  8. Tip: The water filter is usually located on the water side of the hose connection, i.e. where the water enters your pressure washer. You can find out exactly from your operating instructions.
  9. Is the filter damaged? Then replace it with a suitable spare part.
  10. Replace the cleaned or new filter.
  11. Check the impeller of the pump. Is there any damage or are the valves clogged? Clean them, if necessary, or replace defective parts.
  12. Tip: The valves are usually located under hexagonal screws on the head of the pump. You can simply remove them and replace them after cleaning.
  13. Also check the other valves and seals on your pressure washer. Clean them or replace them if necessary.

Why does the pressure washer go on strike? Other possible causes and solutions

You’ve checked all of the above causes, but your pressure washer still isn’t doing what it’s supposed to? Then these three reasons for malfunction remain:

Residual water in the pressure washer

If residual water remains in the pressure washer after use, this can cause the control valve to become rough. Your device can then no longer work properly. To repair the valve yourself, proceed as follows. Attention: Your pressure washer must still be disconnected from the power supply!

Remove the overflow from your pressure washer.

Tip: The overflow is usually located under the pressure adjustment and can be pulled out. You can find out exactly how to do this from the operating instructions.

  1. Carefully remove rough spots with fine sandpaper.
  2. Grease the overflow thoroughly with silicone grease.
  3. Reinstall the part in your pressure washer.
  4. Nothing works without power

If your pressure washer does not work, the fault does not necessarily lie with the device itself. Therefore, also check the power connection for possible defects.

Does the power outlet work? Check whether other devices work with the socket you are using. Try a different wall outlet if necessary.

Is the fuse intact? It is possible that the fuse has blown or is defective. Replace or reinstall it.

Is the power cord undamaged? A broken cable or other damage may be preventing your pressure washer from getting power. Replace the cable in any case. Under no circumstances should you work with a broken cord!

Are you using an extension cord? Then you should test another one. It is possible that the cable or the connector of your extension cord is broken.

Motor damage

If nothing really helps, the problems with your pressure washer can still be caused by a motor damage. However, you should not try to repair it yourself, a professional is needed. But: Repairing a damaged motor can quickly become relatively expensive and is therefore basically only worthwhile with a very new or high-priced pressure washer. If you own a cheaper device or if your pressure washer is already older, a new purchase can be the more sensible solution.

Even laymen can repair many defects on the pressure washer

A pressure washer can be a practical help around the house and garden – if it works. Especially often, the devices have problems with the water pressure. The causes range from broken water hoses to defective valves and seals. Fortunately, these are all things that even non-professionals can repair relatively easily themselves. However, if the problem is with the engine, a professional should definitely be called in.