Pressure washer won't start: Common Causes & How to Fix
1Pressure Washer Spark Plug
Most Common Solution
Repair Instructions:
Check the spark plug for any wear or damage. Look to see if the porcelain is cracked, the electrodes are burnt or broken, or there's heavy carbon buildup. If you see any of that, replace the plug. You can also use a spark tester tool to check for issues. When cranking the engine, you should see a strong spark jump the tester terminals. No spark means the plug is bad and needs a swap. Cracks, burned spots, or carbon indicate failure. Testing with the spark tool verifies if the plug is firing right. Good healthy sparks during cranking mean the plug is still working. But no sparks, or visible damage, mean replacement is needed. Worn or defective plugs can't ignite the fuel mixture properly. Swapping in a new undamaged plug will get strong sparking for good combustion.
How to Replace Pressure Washer Spark Plug
- Disconnect spark plug wire. Use a spark plug wrench to disconnect the spark plug wire from the spark plug.
- Clean area. Use a wire brush to clean any debris around the spark plug. This allows for easier removal.
- Remove spark plug. Place the spark plug wrench on the spark plug and turn counterclockwise to unthread it from the cylinder head.
- Inspect spark plug. Check for heavy carbon buildup or worn electrodes. Replace spark plug if excessively fouled or damaged.
- Set gap. Use a feeler gauge to check and adjust the spark plug gap to manufacturer specifications.
- Apply anti-seize. Apply a small amount of anti-seize lubricant to the spark plug threads to prevent sticking.
- Install spark plug. Thread new spark plug into cylinder head by hand then tighten with the wrench. Do not overtighten.
- Reconnect wire. Reattach the spark plug wire securely on the new spark plug.
- Test operation. Start pressure washer and verify normal operation.
2Pressure Washer Carburetor
Most Common Solution
Repair Instructions:
The issue could be a clogged carburetor. This happens when old fuel sits in the pressure washer. Over time, some fuel ingredients evaporate, leaving a thicker, stickier substance. That sticky stuff can choke up the carburetor, making the engine run rough. Try cleaning the carburetor with spray cleaner. If that doesn't work, rebuild or replace the whole carburetor. Letting fuel sit turns it thick and gummy. Those deposits block proper fuel flow through the carb. First, try spraying cleaner in the carb to dissolve gunk. But if it was really old gas, the carb may be too clogged internally. Rebuilding or replacing the carburetor gets fuel flowing correctly again. Removing old gas and fixing a choked carb can get the engine running smoothly.
How to Replace Pressure Washer Carburetor
- Shut off fuel supply. Turn off the fuel supply valve and disconnect the fuel line from the carburetor. This allows fuel to drain and reduces risk of fire.
- Disconnect throttle linkage. The carburetor throttle arm is connected to the engine throttle control. Disconnect this linkage.
- Remove carburetor. The carburetor is secured with mounting bolts. Remove bolts and carefully lift the carburetor off of the engine intake manifold.
- Install new carburetor. Place new carburetor into position and reinstall the mounting bolts. Do not over tighten.
- Reconnect throttle linkage. Reattach the throttle arm linkage to ensure proper throttle control from the engine.
- Attach fuel line. Connect the fuel supply line back to the carburetor inlet. Use a hose clamp to secure.
- Restore fuel supply. Turn fuel supply back on and check for leaks at connections.
- Reset carburetor adjustments. Make necessary adjustments to the carburetor per manufacturer specs to optimize performance.
- Test operation. Start engine and test operation. Make any additional fine tune adjustments to the carburetor as needed.
3Pressure Washer Ignition Coil
Common Solution
Repair Instructions:
The ignition coil provides voltage to the spark plug when the engine runs. If it's faulty, the engine might not start. Before replacing the coil, check that the spark plug works right. If the plug is good, test the coil with a coil tester tool. If it's defective, swap in a new one. That coil is key for sparking the plug. Make sure the plug isn't the problem first. Use the tester tool to verify the coil is malfunctioning. The tester sends power through the coil to check operation. If it's damaged internally, the tester won't read right. This indicates a bad coil needing replacement. But a good coil reading means it's working properly. Checking the plug and testing the coil isolates an ignition issue. A faulty coil has to be replaced so voltage flows to the plug for starting.
How to Replace Pressure Washer Ignition Coil
- Disconnect spark plug wire. Remove the spark plug wire from the spark plug and ignition coil terminal.
- Remove mounting bolts. Use a socket wrench to remove the two ignition coil mounting bolts.
- Disconnect wiring. Unplug the primary ignition coil wire going to the magneto.
- Remove ignition coil. Lift old ignition coil up and off of the engine to remove it completely.
- Install new coil. Place the new ignition coil onto the engine and align the mounting bolt holes.
- Replace mounting bolts. Thread in ignition coil mounting bolts and tighten securely with a socket wrench.
- Reconnect wiring. Plug the primary ignition coil wire back into the magneto terminal.
- Reconnect spark plug wire. Attach the spark plug wire to the high-voltage terminal on the new ignition coil.
- Test operation. Start pressure washer and check for normal sparking.
4Pressure Washer Flywheel Key
Common Solution
Repair Instructions:
The flywheel key might have snapped in two. This small metal piece fits into the crankshaft and connects to the flywheel. If the washer suddenly hits something hard, the key breaks to prevent engine damage. To check, take the flywheel off the engine and look at the key. If it's cracked, swap in a new one. That little key is designed to shear if the flywheel jams. The key takes the impact rather than the engine internals. Quick stoppage can overload and break it. Removing the flywheel lets you see if the key is intact or fractured. A clean break means it did its job and took the force.
How to Replace Pressure Washer Flywheel Key
- Remove flywheel nut. Use a socket wrench to loosen and remove the nut holding the flywheel in place.
- Extract flywheel. Carefully pull the flywheel off the crankshaft to access the flywheel key.
- Remove old flywheel key. Use a small screwdriver to pry out the damaged flywheel key from the crankshaft keyway.
- Clean keyway. Use a wire brush to thoroughly clean out any debris from the crankshaft keyway.
- Check new flywheel key. Inspect the new key to ensure it is intact and aligned properly in the keyway.
- Install flywheel. Carefully slide the flywheel onto the crankshaft, aligning it with the flywheel key.
- Replace nut. Thread the flywheel nut back onto the crankshaft a few turns by hand first, then tighten securely with a wrench.
- Check alignment. Rotate the flywheel and see that it is properly aligned and seated onto the crankshaft.
- Test operation. Start pressure washer and check for normal operation without excessive vibration.