Why Is My Pressure Washer Not Starting? 8 Common Causes and Solutions

You’ve set aside part of your precious weekend to pressure wash the hardscaping on your property only to find the pressure washer not starting when you’re ready to go. Pressure washers depend on many different parts to do their jobs, so if even one small part wears out, the entire machine can stop working. Here are eight potential reasons your pressure washer won’t start, plus how to fix it and get back to your cleaning spree.

1. The Gas Is Too Old

Gas-powered pressure washers need fresh fuel to wash away the dirt and grime on your home. If the fuel sits for longer than six months, it will oxidize, losing the octane it requires to start up. If you notice the pressure washer starts up but stops running midway through the cleaning job, this is another sign that the fuel is stale.

After changing fuel or oil, make sure to tightly replace any drain plugs. Otherwise, you risk the pressure washer leaking oil. If you’ll be storing the pressure washer for more than three months, drain the fuel before storing to avoid oxidation.

2. There’s Too Much Pressure in the Pump

Pressure is essential to pressure washing, but there’s still such a thing as too much pressure. When excess pressure builds in the pressure washer, it can keep the machine from starting or make it more difficult to pull the trigger on the pressure washer wand. To start a pressure washer safely and prevent excess pressure, always push down on the trigger when you pull the engine cord.

3. The Power Supply Is Faulty

If you don’t use a gas model and are wondering why your electric pressure washer is not starting, the problem could actually be with the power supply. Maybe the outdoor outlet you’re using is faulty, or there’s been a power disruption, such as a tripped breaker.

Check the beaker, but if you try to use the pressure washer again and it trips the breaker, you’ll need to hire a local electrician to inspect the breaker.

4. The Air Filter Is Dirty

If the pressure washer isn’t building pressure or it’s not starting at all, the problem could also be with the air intake. The air filter on a pressure washer can get dirty over time, so replace it after 25 hours of use or at least once per year.

5. The Carburetor Is Clogged

Old or contaminated gas can cause more issues than just a pressure washer not starting. The gas can turn to varnish, which will clog up the carburetor and keep the fuel from reaching the combustion chamber to combust and power the pressure washer.

Clean the carburetor with carburetor cleaner and an old toothbrush or small cleaning brush. If a thorough cleaning of the carburetor doesn’t get the pressure washer back up and running, call in a pro to replace the carburetor or buy a new pressure washer.

6. The Spark Plug Is Faulty

The spark plug is one of the most important parts of a pressure washer because it ignites a mixture of air and fuel to create combustion, which powers the machine. If the pressure washer isn’t starting, the spark plug may be cracked or worn out. 

A spark plug lasts for 100 hours or a year, depending on how often you use the pressure washer. If you can’t remember the last time you replaced the spark plug, it’s time for a new one. Make sure that changing the spark plug is part of your pressure washer maintenance checklist.

7. The Ignition Coil Failed

As the name suggests, you can’t start up or ignite the pressure washer if the ignition coil isn’t working. This part sends voltage to the spark plug, which uses that power to ignite the fuel and air needed for the pressure washer to run. 

Check whether the ignition coil is sparking with a spark tester. If the coil sparks, check that the flywheel gap is at the recommended distance for your machine using a feeler gauge. This is between 0.006 to 0.010 inches or 0.010 to 0.014 inches, but check the user manual to be sure. If the coil doesn’t spark with the spark tester, you’ll need to replace the coil or hire a pro to do it.

8. The Flywheel Key Needs Replacing

The flywheel key is a small but mighty part of your pressure washer that connects the flywheel to the crankshaft for a steady speed between the engine’s power strokes. However, the key can wear out over time or break if the pressure washer is damaged. You’ll need a pro to replace the flywheel key.

What to Do When Your Pressure Washer Isn’t Starting

So many small parts could be the cause of your pressure washer not starting. From a flywheel key that busted on impact to an air filter that’s due for replacement, it’s not always obvious what’s keeping the machine from running properly.

Instead of tearing the pressure washer apart and spending an afternoon testing different parts to find the source of the problem, hire a power washing pro near you to quickly diagnose and repair the issue. You can spend less time trying to fix it yourself and get back to pressure washing the driveway in no time.