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Pressure Washer Problems: Engine & Motor Troubleshooting & Repair

Pressure washers are of great significance for all types of cleaning applications. These devices utilize a powerful four-stroke engine (gas-powered models) or an electric motor to drive the pump and produce a pressurized water jet. Being an owner, you will find situations when your engine/motor isn’t working optimally and the pressure washer underperforms.

Pressure Washer Problems:

The fuel delivery system must be checked if your gas pressure washer doesn’t start or stalls after starting. This system contains fuel lines, air and fuel filters, and the carburetor. Ensure the filters aren’t clogged and the carburetor isn’t plugged with stale fuel deposits. Check the power outlet and voltage level if your electric pressure washer doesn’t start. Ensure that the capacitor isn’t faulty and the extension cord of your device isn’t damaged at some point.

In this article, I will help you troubleshoot gasoline engines and electric motors for any pressure washer brand. I will shed some light on the commonly occurring problems for both types and also discuss possible solution strategies that you can adopt.

Problems with the Gas Pressure Washer Engine

Gas pressure washers use a four-stroke combustion engine to power the pump. Due to the added complexity of the engine and fuel system, there are greater maintenance requirements for these pressure washers. As a result, the associated faults with the engine and fuel system are also greater; hence, they need to be discussed in more detail.

Let’s dive into the engine-related problems of your pressure washer and find their solutions.

● 1. Pressure Washer: Keeps Stopping and Starting

If your pressure washer repeatedly starts and stops, it might be due to a vapor lock triggered by a clogged fuel tank vent. A faulty fuel filter could be the source of this problem in some cases.

Petrol vapors gather when a fuel tank’s vent becomes clogged, increasing the vapor pressure within the tank. This increased vapor pressure generates a vapor lock, which prevents fuel from reaching the carburetor and causes the engine to shut down just after starting.

– Solution:

Simply open your fuel cap and let the vapors escape the tank. Start the engine again. Check to see that the tank’s vent is not clogged with dirt. If this does not solve the problem, examine your fuel filter and replace it if it shows signs of wear.

● 2. Pressure Washer: The engine won’t run

If your engine doesn’t start, check the spark plug to ensure it’s in proper working condition. Remove and dismantle the carburetor and clean its ports using carburetor cleaner liquid if it doesn’t work.

Carbon buildup commonly compromises the electrodes of spark plugs, diminishing spark quality and making it difficult to start the engine.

– Solution:

If the problems continue, consider examining your pressure washer’s carburetor. Remove the carburetor and clean it of any leftover fuel. A carburetor repair kit and cleaning solution to remove sticky residues can be purchased to aid with the repair.

● 3. Pressure Washer: Engine Stops

If your engine stalls shortly after starting, your air and fuel filters must be thoroughly inspected and cleaned from any debris stuck. Check the tank for vapor lock and ensure the carburetor is cleaned and adjusted appropriately.

The air and fuel filters keep foreign particles out of the carburetor. As a result, these filters frequently become clogged with debris, affecting the engine’s air-fuel mixture and resulting in power loss.

– Solution:

Check these filters independently and clean/replace them as needed to fix the problem. If the problem continues, look for a vapor lock in the gas tank and try tightening the carburetor’s adjustment screws.

● 4. Pressure Washer: Engine not providing enough Power

If your engine isn’t producing enough power, ensure the water supply is enough and the water hoses aren’t kinked. Check that the air filter is clean and that the carburetor jets are not blocked with dirt.

The air-fuel mixture may be too rich if the engine isn’t creating adequate power. This indicates that the engine receives too much fuel but not enough air to produce sufficient power after combustion. Either the carburetor or the filters or both might be at fault.

– Solution:

Check the air filter to guarantee enough air supply, which should not be clogged with dust. The carburetor’s L and H screws should be properly adjusted. These screws control the engine RPMs at low and high speeds.

Tightening the L screw restricts fuel flow to the carburetor, causing the air-fuel mixture to become lean. This raises the RPMs of the engine. Loosening the screw, on the other hand, decreases the RPMs. Always maintain the screw midway along both extremes while adjusting the carburetor. This ensures that the RPMs remain optimal and that the engine continues to generate adequate power.

Additionally, check and be certain that no air is trapped in the pump and that the hoses are not kinked, which causes severe back pressure on the engine. As a result, it may not provide adequate power in that condition.

● 5. Pressure Washer: Oil Leak

If your engine is leaking oil, the cause is most likely a defective seal. In virtually all cases, replacing the seal would resolve the issue. In some cases, an overfilled tank might cause oil to spill out.

You can buy an oil seal kit to help you replace seals as needed. Inside the oil, inlets are these oil seals. Usually, there are two inlets sealed with caps on each side of the engine.

– Solution:

Remove the seal and check its condition using a screwdriver. If it looks to be damaged, replace it. As a precaution, avoid overfilling your oil tank, which might leak oil out of these inlets.

● 6. Pressure Washer: Water in Oil

The engine’s oil seal is compromised if water enters the engine oil. In this case, you should replace the seal according to the manufacturer’s instructions.

When water is added to the oil, it turns milky. One probable cause is a leaking oil seal. Another less common factor is a worn-out engine piston. Over time, mechanical wear causes metal to chip off pistons, increasing the space between the piston and the cylinder walls.

As a result, water entering the piston through the inlet manifold may enter the crankcase and mix with oil to produce a milky suspension.

– Fixes:

If your engine is new, the issue is most likely with the seals/gaskets. As a result, you’ll need to replace your engine’s seal/head gasket. If your engine is still covered by warranty, you should contact the manufacturer and request that this replacement be performed. I would not recommend endangering your warranty by performing the replacement yourself.

In the event of a worn-out piston, contact the manufacturer to determine if the engine’s warranty is still in effect. If not, your pressure washer’s engine may need to be replaced.

Electric Pressure Washer Problems

Electric pressure washers require the least maintenance compared to their gas-powered equivalents. Because the fuel and engine are replaced with an electric motor, the probability of failure is reduced, as are noise levels and emissions. As a result, these devices have become rather popular in the market recently and have been discussed in this article.

● Electric Pressure Washer not running

Check the fuse and ensure the electrical outlet works if an electric pressure washer does not start. If it still doesn’t start, the electric motor may have failed.

If your pressure washer isn’t operating, you should check the following:

– Step 1: Check for Power Outlet Issues

The first thing you should do if your electric pressure washer is not working is to check your outlet. Unplug the pressure washer and inspect the outlet with a tester screwdriver or other tool. If it isn’t working and there is a ‘reset’ button, press it. Check the circuit breaker in the fuse box if this does not solve the problem.

– Step 2: Inspect the Fault Circuit Interrupter

As a result of the voltage drop, a ground fault circuit interrupter (GFCI) may have been engaged. Remove the plug from the pressure washer and reset the GFCI. If it still triggers when you connect your pressure washer and it is wet, let it dry before attempting again. There is an issue with the pressure washer if it continues to pop after drying.

– Step 3: Inspect the Extension Cord

Remove the extension cable from your pressure washer and try plugging it in directly. Ensure that the plug is properly inserted into the power outlet. If it works now, the issue was with the extension cable.

– Step 4: Inspect the Fuse

If the power outlet functions correctly (with a bulb or other appliance), you should check to ensure that the fuse within the machine or fitted at the plug of the machine’s cord hasn’t blown out. Look out in the manual if you can’t locate it. If the fuse has blown, you need to change it.

– Step 5: Examine the power cord

If it does not start, your power cord may become damaged. The issue might be resolved by changing the power cord. For this purpose, contact your pressure washer manufacturer to ascertain if the warranty still holds. If it doesn’t, you should consider changing the chord by yourself.  

– Step 6: Inspect the Capacitor

A faulty capacitor is often the cause of a buzzing sound from your pressure washer’s motor. You can replace it if you have the appropriate skill level.  If not, consult a professional to get it done for you.

If the machine still won’t start, have your manufacturer inspect the electric motor and replace it if it’s still under warranty.

● Electric Pressure Washer Motor Stops

If your pressure washer motor stops operating, the most likely cause is a power failure in the socket or a faulty capacitor. Occasionally, a voltage drop in the socket may force it to shut down.

The motor shuts off when the voltage falls below a certain threshold. Using a multimeter, check the voltage level in the socket. The required voltage for pressure washers varies depending on where you reside. Typically, the pressure washer can operate at voltage levels ranging from 140V to 240V.

If the voltage level is fine and the washer still doesn’t start, check the motor’s capacitor, as it might need to be changed. If you had been hearing a humming sound from your motor lately, it was probably due to a faulty capacitor. Replace the capacitor with an identical one and check the pressure washer motor again. Hopefully, it will restart now. If it still doesn’t start, your electric motor has become faulty.

Pressure Washer troubleshooting table:

The pressure washer is not producing high pressure
Hose with small diameter
Replace your hose with a 1″ (25mm) or 5/8″ (16mm) hose
Restricted water supply to the washer
Check for the kinks and leaks in the hose
Inadequate water supply
Ensure the water source is unobstructed and fully turned on
Clogged intake filter
Remove the filter and rinse it with warm water
Air in the pump
Ensure that the hose and fittings are airtight. Shut off the washer and squeeze the trigger until water flows steadily from the spray tip
The suction tube or detergent bottle is not connected properly
Install the suction tube and detergent bottle correctly
Detergent too thick
Dilute the thick detergent by adding water
Obstructed spray tip
Remove the debris with a needle
No pressure tip on the wand
Install a suitable pressure tip at the end of the wand
If your model has a belt, it can be loose.
Tighten or replace the belt.
Pulsing pressure washer (output pressure varies high and low)
Inadequate water supply
Ensure that the water source is fully on and check the hose for kinks and blockage
Obstructed spray tip
Remove the debris with a needle
Pump sucking air
Ensure that the hose and fittings are airtight. Shut off the washer and squeeze the trigger until water flows steadily from the spray tip
Clogged intake filter
Remove the filter and rinse it with warm water
Calcified hose, tip, or trigger
Clean the hose, pressure tip, or trigger with vinegar or a cleaner designed for this purpose
Noisy Pump
Air in the pump
Ensure that the hose and fittings are airtight. Shut off the washer and squeeze the trigger until water flows steadily from the spray tip
Clogged inlet filter
Remove the filter and rinse it with warm water
Pump leaking water
Damaged or worn water seals
Replace the seals with new ones or call a professional
Loose fittings
Ensure that all the fittings are tight
Erratic water pressure, changing up and down
Unloader valve
Check and clean the unloader valve. If in bad shape, replace it
No output pressure. Or the motor stops when using the trigger (electric models)
Unloader valve
Check and clean the unloader valve. If in bad shape, replace it

● Gas Pressure Washer Engine troubleshooting table:

The motor won’t start
The power switch is in the “OFF” or “0”  state
Turn the power switch “ON” or “1”
Cord not plugged
Plugin the power cord
Damaged, too long, or improper extension cord
Replace the existing cord with a 25′ (7.6m) 14 AWG cord or a 50′ (15m) 12 AWG cord
Inadequate power from the electrical outlet
Plug the cord into a different outlet
The pressure washer circuit breaker tripped
Please wait for the washer to cool down and restart it
The motor buzzes but fails to run
Loss in voltage due to the extension cord
Plug the unit directly into the outlet without an extension cord. If the problem isn’t solved, replace the extension cord
Low supply voltage
Ensure that only the pressure washer runs on that circuit at the time of use
Residual pressure in the system
Shut off the washer and squeeze the trigger to release pressure
Residual friction among the internal components
Cut the water supply and turn the machine ON for 2 to 3 seconds. Try it a couple of times or until the motor starts. Don’t let the machine run dry for more than 3 seconds.
Unit not used for long periods
I recommend calling a professional for help
Motor not working
Faulty Timer
Disconnect the leads from the timer. If your pressure washer doesn’t turn off after the time out, the timer is faulty, and you need to replace it.

● Electric Pressure Washer Motor troubleshooting table:

Leaks in the spray wand, spray tip, or extension
Damaged or broken O-rings or plastic insert
Replace the worn O-rings or call a professional
Pressure washer pump dripping oil
Worn or damaged oil seals
Inspect the oil seals and replace them if worn
No water from the washer outlet
The water supply is off
Turn the water supply ON
Kink in the hose or faucet not fully open
Remove any kinks and debris from the hose or water lines. Check and fully open the faucet.
The motor won’t start
Check the battery
Check if the battery is charged correctly. Charge or replace when in bad condition. Examine the battery terminals for a proper connection. Clean if needed.
Check the fuel filter
Clean the fuel filter if dirty. In that case, check the gas tank, as this is the most likely culprit.
Check the gas supply
Check the fuel level and add if needed. Ensure that the gas can flow to the carburetor. Remove any blockage.
Check the Air-filter
Clean the air filter. Replace it when it is in bad condition or it is a paper air filter.
Check the carburetor
Remove and clean the carburetor with some carb cleaner. It is also possible to clean it without removing it.
Fuel gap blocked
Check that the hole in the fuel cap is open. Clean if needed.
The engine is stalling, or starts and stops
Check the carburetor
Remove and clean the carburetor with some carb cleaner. It is also possible to clean it without removing it.
Air filter
Clean the air filter. Replace it when it is in bad condition or it is a paper air filter.
Check for bad gas
Suppose you have old gas, more than a few months old. It can turn bad. Drain and replace the gas. Next time add a fuel stabilizer.