Pressure Washer Troubleshooting Guide

If you own a pressure washer, and you’re all geared up to use it and for some reason, it has a problem, you can do one of two things. Reach for the user manual, or search online. Seeing as you’re here you obviously searched online, and it’s just as well you did.

Because here you’ll find all of the common faults that affect pressure washers along with the easiest cures. From low pressure, motor cut-outs, water leaks, oil leaks, and much more.

So let’s jump straight into the most common pressure washer problems, and how to fix them.

Common Pressure Washer Faults And Fixes

We’ve tried to make this as easy to follow as possible so you can get it fixed and get back on with your pressure washing in as short amount of time as possible.

Problem	Probable cause	Cure
Low water pressure	Not enough water supply to the pressure washer	Remove any kinks from the hose, turn the tap on fully, check the hose for blockages, make sure hose diameter is adequate. Check nozzle is correct for use.
Low water pressure	Blocked inlet filter	Remove hose, clear blockage and reconnect the hose.
No Water pressure	Faulty unloader valve	Check for damage, check seals spring, check calibration. Repair or replace as necessary
No water pressure	Faulty pump	Remove pump replace or repair
Pulsating water pressure	Air blockage	Turn off the machine press trigger as water runs through it will remove any air.
Pulsating water pressure	Faulty pump	Repair or replace the pump
Pulsating water pressure	Blocked nozzle	Use the tool provided to clean the nozzle and flush with water
Pulsating water pressure	Unloader valve calibrated incorrectly	Check the user manual for correct calibration and recalibrate
Pressure drops as soon as you start using.	Blocked nozzle	Clean with the tool provided
Pressure drops as soon as you start using.	Unloader valve Problem	Check unloader valve and repair or replace as necessary
Pressure washer working but not cleaning	Wrong nozzle	Change to a higher pressure nozzle
Water pump leaking	Thermal valve activated	Wait 5 minutes and try again
Water pump leaking	Bolts loose on the pump	Retighten the bolts and make sure casing is fitted together correctly
Water pump leaking	Damaged seals, pump cracked	Replace pump (contact manufacturer if still on warranty)
Water leaking from the garden hose	Bad connections	Reconnect properly or replace washers.
Water leaking from the wand	Worn washer	Replace the washer
Detergent Injector not working	Wrong nozzle	Use the black detergent nozzle
Detergent Injector not working	Soap inlet filter blocked	Flush with water
Detergent Injector not working	Detergent too thick	Dilute with more water
Machine louder than normal	Blocked water intake	Check and clean
Machine louder than normal	Oil level low in the pump	Check and add oil (if possible) if not contact the manufacturer
Machine louder than normal(Petrol models)	Low oil level in the engine	Check and add oil as necessary
Oil leaking from the water pump	Loose bolts	Retighten the bolts
Oil leaking from the water pump	Damage to the internal parts of the pump	Check your warranty and contact the manufacturer or repair and replace.

Common Faults With Electric-Powered Pressure Washers

The following problems only affect electrical pressure washers.

Problem	Probable cause	Cure
Motor cuts out	Low voltage	Try moving to a different plug socket and removing any extension cable
The machine doesn’t start	Not plugged in	Plug it in
The machine doesn’t start	Socket switch is off	Turn the power supply on
The machine doesn’t start	The power supply is faulty	Check socket, cable, plug, fuse and replace repair or move to a different socket
The machine doesn’t start	Faulty motor	Contact the manufacturer and return under guarantee

Common Faults With Petrol-Powered Pressure Washers

The following problems only affect petrol pressure washers.

Problem	Probable cause	Cure
Engine won’t start	No fuel	Fill with the correct fuel
Engine won’t start	Air block	Use correct start-up procedure to release air blockage
Engine won’t start	Choke and/or throttle needs adjusting	Adjust choke and throttle
Engine won’t start	Faulty spark plug connection	Check and reconnect the spark plug wire
Engine won’t start	Faulty spark plug	Remove, inspect, clean or replace.
Engine cuts out while in use	Oil level too low	Check oil level and refill as necessary
Engine cuts out while in use	Clogged air filter	Remove the air filter, clean or renew and replace.
Not enough power from the engine	Clogged air filter	Remove the air filter, clean or renew and replace.
Not enough power from the engine	Engine running too slow (or too fast)	Check the handbook for specs and adjust engine speed
Oil leaking from the engine	Worn seals	Check the warranty, if you’re not covered replace the seals.
Milky looking oil in the engine	Water entering through worn or damaged pistons.	Contact manufacturer.

That’s all the common faults you’re likely to come up with while operating (or trying to operate) your pressure washer. You’ll see from the chart above that electric-powered pressure washers have fewer faults to petrol-powered models. That’s not because they are better quality machines, it’s because with a motor replacing the engine, there are fewer working parts to go wrong.

That said, you can’t really repair an electric motor without being an electrician whereas you don’t have to be a mechanic to tinker with a petrol engine (within reason). Also before messing with any parts, or dismantling anything, always check your warranty first. Because once you dismantle anything you run the risk of voiding the warranty.

What’s Better Electric Or Petrol-Powered Pressure washers?

There are pros and cons to each type and it really is down to personal preference. But as a rough guide, here’s a quick comparison chart.

Pros And Cons For Electric-Powered Pressure Washers

Pros	Cons
Light-weight	Lower power range
Less maintenance	Limited lifespan
Quieter	Ties by a cable (less mobility)
Easy to operate	Coldwater only
A larger choice of attachments
Cheaper purchase price

Pros And Cons For Petrol-Powered Pressure Washers

Pros	Cons
More powerful PSi	Heavier to move
No cables to hold you back	Cost more to purchase
Considerably longer lifespan	High maintenance (fuel, oil, filters, spark plug, repairs)
Hot water cleaning power	Louder
More accessibility for repairs	Harder to start
	Limited range of accessories

For much more information about gas vs electric pressure washers follow this link