Power washers usually act up in a few predictable ways. The burner will not light on hot-water units, the pressure suddenly drops or disappears, the water stays lukewarm, or you notice leaks around fittings and hoses. Most of the time you can narrow it down fast with simple, safe checks: make sure the water supply is steady, clean the inlet screen, check the nozzle for blockage or wear, remove hose kinks, and confirm fuel and basic power.
From there, the guide helps you match the symptom to the most likely cause. Burners often refuse to fire when flow or settings are wrong, pressure problems usually come from the nozzle or restricted inlet flow, low heat is commonly tied to flow, thermostat settings, or scale buildup, and leaks are often worn O-rings, loose quick-connects, or cracked hose ends. It also explains why these problems keep coming back, like hard water scale, using the wrong tip size, running the unit dry, chemical damage to seals, and poor storage that speeds corrosion.
The key theme is safety. Do the quick checks, but stop immediately and call a qualified technician if you smell fuel, see oil leaks, notice electrical faults or wet electrics, get pressure surging with strange pump noise, see high-pressure spray leaks, or the burner and heat still will not work after the basics. Regular small maintenance, like checking screens and nozzles, flushing after use, replacing O-rings early, and storing the unit in a dry place, prevents most breakdowns and keeps jobs moving.
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Common Power Washer Issues and Safe First Checks
Basic checks reveal most power washer issues without tools. Check the trigger gun position to ensure it stays released for full flow. Verify the water supply provides steady inlet pressure from a tap or tank. Clean the inlet filter or screen to remove debris that blocks flow. Inspect the nozzle or spray tip for clogs or wear that reduce pressure. Look for hose kinks that restrict water movement. Spot visible leaks at connections before starting the unit. For hot water units, confirm fuel levels in the tank. Test the power supply basics like cords and outlets for electric models or battery charge for cordless ones.
These checks take little time and fix simple problems on job sites. For example, a clogged inlet screen often causes low pressure during driveway cleaning in Sydney’s hard water areas.
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1. Burner Not Lighting (Hot Water Units)
Burners fail to light most often due to insufficient pressure or flow that prevents ignition. Hot water power washers require correct pressure and flow for the burner to fire safely. Common causes include low fuel, blocked airflow, or a thermostat set too low. Wrong settings stop the flame sensor from activating.
Perform safe checks like confirming fuel levels in the tank for diesel or kerosene models. Turn on the burner switch and adjust the thermostat to a higher setting. Pull the trigger gun to ensure flow activates the pressure switch or flow switch. Look for obvious airflow blockages around the unit.
Stop and call a qualified technician if the burner shows no signs of ignition after these checks. Fuel smells or electric issues raise carbon monoxide risks. Prevention involves regular fuel filter inspections at a high level to avoid repeats, especially in Sydney’s humid storage conditions that promote corrosion. NSW Health carbon monoxide fact sheet (includes pressure washers).
Read it in more detail: Hot water vs cold water power washing.
2. Loss of Pressure or No Pressure
Loss of pressure usually stems from nozzle wear or inlet restrictions that disrupt flow. Nozzles clog or wear out, reducing PSI under load. Inlet filters block with debris, causing cavitation where air enters the pump. Unloader valves stick at a high level, but avoid adjustments. Insufficient water flow from the supply worsens this.
Check the nozzle for clogs by removing and rinsing it. Inspect the inlet screen for buildup and clean it. Bleed air from the system by running water through the hose without the nozzle. Ensure the spray tip size matches your unit’s rating.
If pressure drops suddenly with surging or pulsation, stop and call a technician. This signals deeper pump issues. Prevent problems by using the right tip size for tasks like patio cleaning, and flush the system after use to avoid scale in hard water regions.
Read it in more detail: Psi flow rates for power washing.
3. Low Temperature or No Heat
Low temperature results from thermostat settings or restrictions that limit heat transfer. Scale buildup in hot water units reduces efficiency. Fuel delivery restrictions at a high level affect burner performance. Pressure and flow must stay steady for heat to build, as low flow stops the burner.
Verify the thermostat setting matches your needs. Check overall water flow to ensure it meets the unit’s requirements. Look for signs of heat loss like exposed coils in cold weather.
Stop if the temperature fails to rise after basics, or if you notice overheating. Fuel or electric risks demand a technician. Prevent this by descaling at a high level periodically, especially in areas with hard water like Sydney driveways where scale forms fast.
Read it in more detail: How temperature affects power cleaning.
4. Leaks (Water, Oil, Fuel Smell)
Leaks appear at common points like quick-connect couplers due to worn seals. O-rings degrade over time, causing drips at fittings. High-pressure hoses crack at ends from repeated use. Pump manifold seams may show issues at a high level, but avoid inspection.
Triage leak severity: A slow drip differs from a spray that loses pressure fast. Check and tighten quick connections. Inspect hose ends for visible damage.
Stop for any fuel smell, oil leaks, or high-pressure sprays that pose injection risks. Electrical exposure near leaks requires immediate technician help. Prevent leaks by replacing O-rings before they fail and storing units away from coastal salt air corrosion.
Read it in more detail: Fuel types for hot water power washers.
5. Machine starts but stops, or will not stay running
You might notice the unit starts and then dies, only runs while the trigger is held, or cuts out randomly during use. The most common reasons are power supply problems on electric models, fuel or air delivery issues on petrol or diesel units, thermal overload on the electric motor, low-oil shutdown on many engines, or trigger gun and unloader valve behavior where pressure build-up causes the machine to cycle and stall. For quick, safe checks, try plugging an electric unit into a different outlet, confirm your extension lead is the right rating, and let the motor cool if it has overheated. For petrol units, check the fuel level, confirm the choke position, inspect the air filter, and make sure the spark plug lead is firmly connected. On engine-driven units, check the oil level first, because many will not keep running if the oil is low.
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6. No water coming out
You will usually notice the motor runs but nothing, or only a very small amount, comes from the gun. This is most often caused by the water supply being turned off or restricted, a blocked inlet screen, the pump not being primed due to an airlock (common with tank-fed setups), or hose connections that are not fully seated, including a quick-connect that has not properly clicked into place. For quick, safe checks, turn the machine off, squeeze the trigger, and confirm water flows freely from the hose before reconnecting. Then re-seat all quick-connects and inspect the o-rings for damage or misalignment. To prime the pump, feed water to the unit, keep the trigger open, and purge air until the water flow becomes steady and solid.
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7. Detergent not drawing
If your soap bottle stays full and you get no foam, it usually means the washer is not drawing detergent into the stream. The most common causes are using the wrong nozzle (most units only siphon soap on a low-pressure or dedicated soap tip), a clogged injector or a stuck check valve, or detergent that is too thick or mixed at the wrong dilution. For quick, safe checks, switch to the soap nozzle or low-pressure tip first, then flush the injector with clean water to clear any blockage. Finally, confirm your detergent mix and dilution match what your pressure washer and injector are designed to pull.
Read it in more detail: How temperature affects power cleaning.
Troubleshooting Matrix (Symptom → Likely Cause → Safe Check → Stop Point)
This matrix guides you through the four core problems. It shows symptoms, usual causes, quick safe checks, and when to stop.
| Symptom | Likely Cause | Safe Check | Stop Point |
| Burner not lighting (hot water units) | Low fuel, wrong thermostat setting, poor flow | Check fuel level, burner switch, thermostat dial, trigger pull | Fuel smell, no ignition after basics, electric faults |
| Loss of pressure or no pressure | Clogged nozzle, inlet restriction, air in system | Inspect nozzle condition, clean inlet screen, bleed air from hose | Sudden drop with surging, pump noise changes |
| Low temperature or no heat | Thermostat issue, scale buildup, flow dependency | Verify thermostat setting, check water flow rate | No heat rise, fuel delivery signs, overheating |
| Leaks (water, oil, fuel smell) | Worn O-rings, loose fittings, hose damage | Tighten quick-connect couplers, inspect hose ends | Fuel or oil leaks, high-pressure sprays, electric risks |
Use this matrix for fast root-cause direction. It helps trades operators minimize downtime on commercial jobs.
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Why Problems Repeat (Root Causes Most Guides Miss)
Problems repeat because users overlook water quality and storage habits. Hard water causes scale buildup that clogs systems. Wrong nozzle sizes lead to surging under load. Running units dry damage pumps through cavitation. Chemical misuse erodes seals. Blocked filters go unnoticed until pressure drops.
If you see surging, it usually means air leaks or inlet restrictions. Prevention starts with filtered water supplies. Store units properly to avoid humidity damage, like in Sydney’s coastal air that speeds corrosion.
Read it in more detail: Power washing vs pressure cleaning.
Preventive Maintenance That Prevents Most Breakdowns
Preventive maintenance stops 80% of breakdowns with simple routines. Daily checks include inlet screens and nozzle conditions before jobs. Weekly tasks cover hose inspections for kinks and quick connections for tightness. Monthly reviews involve fuel levels for hot units and overall cleaning to remove debris.
Store units in dry spots to fight humidity, such as in Sydney garages away from salt air. Keep handy parts like O-rings, spray tips, and inlet screens without overstocking. Flush systems after use to clear chemicals and scale. These steps boost uptime on job sites and cut downtime costs.
When to Call a Technician
Call a technician now if:
- You smell fuel or notice oil leaks.
- Electrical components show faults or wet areas.
- Burner fails to light after basic checks.
- Pressure surges with unusual pump noise.
- Leaks spray under high pressure.
- Heat fails to rise, suggesting carbon monoxide risks.
- Any disassembly seems needed.
Continue safely after checks if:
- Issues resolve with clean nozzles or screens.
- Pressure returns after bleeding air.
- Leaks stop with tightened fittings.
- Flow improves from better water supply.
This guide helps buyers decide between service, parts, or replacement.
Safe work in australia read it in more detail: Safe work australia.
Conclusion
Most pressure washer problems come down to a few simple things like water flow, a blocked nozzle, worn seals, or basic maintenance being skipped. A handful of quick checks and better everyday habits can fix many issues early, keep you safe, and help you decide when it’s time to call a professional so your machine stays reliable for years.
FAQs
1. Why did my pressure washer suddenly lose pressure?
Ans. Nozzle wear is a common cause of sudden pressure loss because the orifice enlarges over time, and this change drops PSI when the unit operates under full load. Check the spray tip for clogs first. If it persists, inspect the inlet filter for restrictions that limit flow.
2. What is the most common cause of low pressure?
Ans. Clogged nozzles rank as the most common cause of low pressure since debris buildup narrows the opening, and even minor blockages reduce water output significantly. Rinse the tip to test. Poor water supply adds to this issue on job sites.
3. Why does my hot water pressure washer burner not ignite?
Ans. Burner ignition fails due to low fuel levels in the tank because the system requires adequate diesel or kerosene, and insufficient supply prevents the flame sensor from activating. Verify the thermostat setting. Flow switches demand steady pressure to start.
4. Can low water flow stop the burner from firing?
Ans. Low water flow stops the burner from firing because the pressure switch needs consistent GPM, and reduced flow below specs halts ignition for safety. Test inlet supply rate. This dependency protects against overheating in hot water models.
5. Why does my pressure washer surge or pulse?
Ans. Surging happens from air in the system because cavitation introduces bubbles into the pump, and this instability causes pressure fluctuations during operation. Bleed the hose to remove air. Inlet restrictions worsen pulsing under load.
6. What causes leaks at the quick connection?
Ans. Worn O-rings cause leaks at quick connections because seals degrade from repeated use, and material fatigue allows water to escape under pressure. Inspect fittings for damage. Loose couplers add to this in high-vibration jobs.
7. Why is my pressure washer not getting hot enough?
Ans. Thermostat settings lead to low heat because incorrect dials limit temperature rise, and settings below requirements keep water tepid even with good flow. Check the dial position. Scale buildup constrains heat transfer in hard water areas.
8. Is it safe to use a pressure washer if it is leaking?
Ans. Leaks make use unsafe if they involve high-pressure sprays because injection injuries occur from forceful water, and any fuel or oil involvement raises fire risks. Stop for drips near electrics. Triage severity before continuing.
9. How do I prevent pressure washer problems on job sites?
Ans. Daily inlet filter cleaning prevents problems on job sites because debris accumulation restricts flow, and regular rinses maintain steady pressure during tasks. Use proper storage. Compliance with safety checks cuts downtime costs.
10. When should I stop troubleshooting and call a service tech?
Ans. Stop troubleshooting when fuel smells appear because this signals potential carbon monoxide hazards, and untrained handling risks explosions or fires. Call for electric faults. Any heat-related issues demand pros.
