What Are the Most Common Pressure Washer Problems and How Do I Fix Them?

Pressure washer problems are usually caused by restricted water flow, worn components, or incorrect setup rather than major mechanical failure. Most issues can be diagnosed and fixed at home with basic checks before you ever need a repair technician.

Below are the most common pressure washer problems, what causes them, and how to fix them effectively:

1. Low Pressure or No Pressure at All

This is the most common pressure washer problem and is almost always linked to water supply issues. Kinked hoses, partially closed taps, clogged inlet filters, or blocked nozzles can all reduce pressure dramatically.

Start by checking that the tap is fully open and the hose isn’t kinked or leaking. Remove and clean the inlet filter where the hose connects to the washer. Next, check the spray nozzle and clean it with a nozzle pin or replace it if it’s worn. If pressure is still low after these checks, the unloader valve or pump seals may be worn.

2. Pressure Washer Pulses or Surges

Pulsing pressure usually means air is trapped in the system or water flow is inconsistent. This can happen if the hose connections aren’t airtight or the water source can’t deliver enough flow.

To fix this, turn off the washer, disconnect the spray gun, and let water run through the hose and machine for about a minute to remove air. Reconnect everything tightly before restarting. A dirty inlet filter or partially blocked nozzle can also cause pulsing, so cleaning both should always be part of the fix.

3. Pressure Washer Won’t Start

If a pressure washer won’t start, the cause depends on whether it’s electric or petrol-powered.

For electric pressure washers:

• Check the power outlet
  

• Reset the safety switch
  

• Use a heavy-duty outdoor-rated extension lead
  

For petrol pressure washers:

• Check fuel and oil levels
  

• Make sure the choke is set correctly
  

• Inspect the spark plug for fouling
  

4. Pressure Washer Cuts Out During Use

Pressure washers that shut off while running are often overheating or triggering a safety feature. Turn the washer off and let it cool completely. Check hoses and nozzles for blockages and avoid running the washer continuously without spraying.

5. Water Leaking from the Pressure Washer

Leaks are usually caused by worn O-rings, loose hose connections, or cracked hoses. Even small leaks can reduce pressure and damage the pump over time. Tighten all fittings and inspect O-rings for wear. Replacing O-rings is inexpensive and often solves the issue immediately. Any hose that’s cracked, bulging, or leaking should be replaced. Leaks coming from inside the pump housing usually mean internal seal failure and require professional repair.

6. Detergent Not Dispensing Properly

If detergent isn’t being drawn into the system, the most common cause is using the wrong nozzle. Most pressure washers only dispense detergent when a low-pressure nozzle is attached. Switch to the detergent nozzle and check the detergent hose for blockages or cracks. Also ensure the detergent is diluted correctly. 

7. Pressure Washer Vibrates or Makes Unusual Noises

Excessive vibration or unusual noises often indicate air in the system, loose fittings, or pump wear. Check all hose connections and remove air from the system by running water through before starting the machine.

Why do pressure washers go from strong to frustrating so quickly?

Pressure washers go from strong to frustrating so quickly because they rely on a very tight balance of water flow, pressure, and temperature. When everything is working perfectly, the pressure feels powerful and effortless. As soon as one small part is affected, performance drops fast and noticeably, which is why the change feels sudden rather than gradual.

The most common reason is restricted water flow. A slightly kinked hose, a partially blocked inlet filter, low mains pressure, or a dirty nozzle can all cause a sharp loss of pressure. Because a pressure washer amplifies water flow, even minor blockages have a big impact, turning strong spray into weak or pulsing pressure almost immediately.

Wear and heat also play a role. Components like O-rings, pump seals, and unloader valves work under constant strain. As they begin to wear or overheat, pressure becomes inconsistent. Letting the washer run without pulling the trigger can quickly build heat in the pump, triggering safety mechanisms or causing seals to fail, which adds to the frustration. 

Why will my pressure washer not start when I need it?

A pressure washer often won’t start when you need it because built-in safety systems stop the machine as soon as something isn’t right. What feels like sudden failure is usually the washer protecting itself from damage rather than a major mechanical fault.

The most common causes are power or fuel issues and restricted water flow. Electric pressure washers may not start if a safety switch has tripped, the extension lead isn’t rated correctly, or the outlet isn’t supplying steady power. Petrol pressure washers are equally sensitive and won’t start if fuel is old, oil levels are low, or the choke is set incorrectly. Pressure washers also rely on proper water flow to start. A kinked hose, blocked inlet filter, or trapped pressure from the last use can prevent the motor from engaging. Releasing the trigger, checking the water supply, and clearing filters often solves the issue immediately.

Why does my pressure washer lose pressure or feel half as strong as last time?

Loss of pressure is a common symptom of pressure washer problems that Australian users face, primarily indicating an obstruction or air leak that restricts water flow.

Causes and Fixes for Weak Pressure

1. System Blockages:

• Low pressure is often caused by a clogged inlet screen, mineral buildup inside the wand, or a worn-out nozzle tip.
  Clean the filters/screens and descale the wand or replace the nozzle.

2. Air Intake/Loose Connections:

• Air entering the pump due to loose hose fittings disrupts pressure consistency.
  Inspect and fully tighten all connections to ensure an airtight seal.

3. Restricted Supply:

• The pump is starved if the garden hose feeding the unit is kinked or pinched. Ensure the entire supply hose is straight and provide a full, uninterrupted flow of water.

Why does the spray pulse or surge instead of staying steady?

A pressure washer spray pulses or surges instead of staying steady because the machine isn’t receiving a consistent flow of water or the pressure isn’t being regulated smoothly. Pressure washers rely on even water supply and stable internal pressure, so when either fluctuates, the spray quickly becomes uneven.

The most common cause is air in the system. This can happen if the washer is started before water fully fills the pump, if hose connections aren’t sealed tightly, or if the unit has been sitting unused. Air pockets move through the pump and cause pressure to rise and fall rapidly, which you feel as pulsing at the nozzle.

Another frequent reason is restricted water flow. A blocked inlet filter, kinked hose, low mains pressure, or dirty nozzle can limit how much water reaches the pump. When the pump can’t get enough water, it repeatedly builds pressure and then drops it, creating a surging spray rather than a steady stream.

Why does my pressure washer leak from the gun, hose or base?

A pressure washer leaks from the gun, hose, or base because it can’t hold pressure where it should. These machines run at very high pressure, so even small seal or fitting issues quickly show up as leaks. Leaks from the gun or hose are usually caused by worn O-rings or loose connections. These rubber seals wear out over time and are easy and inexpensive to replace. Simply tightening the fitting or swapping the O-ring often fixes the problem. Leaks from the base are more serious and usually point to internal pump seal or valve failure. 

Why does water flow from the gun before I pull the trigger?

Water flowing from the pressure washer gun before you pull the trigger usually means there’s residual pressure or water already sitting in the system. When the tap is turned on, water fills the hose and spray guns straight away. If the washer wasn’t fully depressurized after the last use, some water can escape from the gun before the trigger is engaged, especially at low pressure.

Another common cause is wear inside the spray gun trigger valve. Over time, the internal seals or spring can wear down or collect grit, which stops the valve from sealing tightly. When this happens, water seeps through even when the trigger isn’t pulled. In some cases, a small amount of flow is normal when first connecting the water supply. However, if water continues to flow steadily from the gun without touching the trigger, it’s a sign the trigger valve or seals need replacing. Swapping the spray gun or rebuilding the valve usually fixes the issue quickly.

Why does my washer shut off as soon as I release the trigger?

A pressure washer shutting off as soon as you release the trigger is usually doing exactly what it’s designed to do. Most modern pressure washers have a built-in auto stop or total stop system that turns the motor off when the trigger is released and restarts it when you pull the trigger again.

However, if the washer shuts off and doesn’t restart smoothly when you pull the trigger again, the issue is often pressure-related. Trapped pressure in the hose, a sticking unloader valve, or restricted water flow can stop the motor from re-engaging properly. Common causes include a kinked hose, blocked inlet filter, dirty nozzle, or air in the system, all of which prevent pressure from equalizing correctly.

Why does my washer make more noise than usual?

A pressure washer makes more noise than usual when the pump isn’t getting a smooth, consistent flow of water. The most common cause is air in the system, which can happen if the washer is started before water fully fills the pump, if hose connections aren’t sealed tightly, or if the machine has been sitting unused. Air causes the pump to cavitate, leading to rattling, knocking, or a harsher sound than normal during operation.

Another frequent reason is restricted water flow or internal wear. A blocked inlet filter, kinked hose, dirty nozzle, or low mains water pressure forces the pump to work harder, increasing noise. If the washer stays loud even after checking hoses, filters, and nozzles, the noise may be coming from worn pump valves, bearings, or a sticking unloader valve, which usually means the washer needs servicing.

Why do pressure washer hoses burst or swell?

A hose bursts when pressure builds up behind an obstruction. If the nozzle is blocked, the hose becomes the weakest point in the system, and it expands until it gives way. Hoses also weaken after years of bending, exposure to sunlight and storage on dusty garage floors. Once cracks develop in the outer layer, the hose struggles to hold pressure safely.

Why does my detergent function stop working even when the tank is full?

A pressure washer’s detergent function often stops working even when the tank is full because detergent is only drawn through the system at low pressure. If you’re using a high-pressure nozzle or lance, the washer physically cannot siphon detergent, regardless of how much is in the tank. 

Another common cause is a blocked or restricted detergent pickup system. Dried soap, thick detergent, or debris can clog the detergent hose, filter, or injector, stopping suction completely. Detergent that isn’t diluted correctly or isn’t designed for pressure washers can also be too thick to draw through. Flushing the detergent line with clean water and checking the small filter often fixes the issue. If it doesn’t, the detergent injector valve may be worn and need replacing.

Why is steady maintenance important for preventing pressure washer problems?

Steady maintenance is important for preventing pressure washer problems because these machines depend on clean water flow, tight seals, and stable pressure to operate properly. Small issues like grit in the inlet filter, a slightly blocked nozzle, or a drying O-ring don’t usually cause immediate failure, but they quietly put extra strain on the pump. Over time, that strain shows up as common pressure washer problems such as loss of pressure, surging spray, leaks, or the washer refusing to start.

Regular pressure washer maintenance helps stop those small issues from building into bigger ones. Simple habits like flushing detergent lines, cleaning filters, checking hoses, and releasing pressure after use protect critical components like the pump, unloader valve, and seals. When maintenance is consistent, the washer runs more smoothly, lasts longer, and is far less likely to let you down when you need it most.

How do climate and water quality affect the machine over time?

Climate and water quality affect a pressure washer over time because both place ongoing stress on the pump and seals. In hot Australian conditions, heat causes rubber O-rings and seals to dry out and harden faster, increasing the risk of leaks and pressure loss. Cold weather can be just as damaging, as water left inside the pump or hose can expand and crack internal components if the washer isn’t properly drained after use.

Water quality also plays a major role in long-term pressure washer performance. Hard water, sand, or mineral-heavy supply slowly wears down valves, blocks inlet filters, and erodes pump parts from the inside. Over time, this leads to common pressure washer problems such as pulsing spray, reduced pressure, and internal leaks. Regularly cleaning filters, flushing the system, and using clean water where possible helps protect the machine from gradual damage caused by climate and water conditions.

When is it better to replace the washer instead of repairing it?

It’s usually better to replace a pressure washer instead of repairing it when the problem involves major internal components and the cost of repair is close to the price of a new machine. Issues like a cracked pump housing, repeated pump seal failures, worn pistons, or motor damage are expensive to fix and often signal that the washer is nearing the end of its lifespan. If the unit is out of warranty or has already needed multiple repairs, fixing one fault often leads to another appearing soon after.

Replacement also makes sense when reliability becomes an ongoing issue. If your pressure washer regularly loses pressure, leaks from the base, won’t start easily, or shuts off during use despite proper maintenance, the internal wear is usually too advanced for repairs to be worthwhile. Newer pressure washers are typically more efficient, quieter, and easier to maintain, which makes replacing an unreliable machine the more practical and less frustrating option long term.

If you want better hoses, replacement parts or a pressure washer designed for steady Australian conditions, explore the range at Blahst. Choose tools that keep the water flowing smoothly and help you clean your home or workshop without interruption.