Common Pressure Washer Problems and How to Fix Them

Pressure washers use a gas engine or electric motor, pump, and concentrating nozzle to boost water pressure from your garden hose as much as 60 times. That allows them to be effective at blasting away driveway stains, deck mildew, and another grudge that would have been impossible to clean using a hose. They are also quicker and easier to clean chairs and other items.

But these handy machines can also have their share of issues, just like other equipment. The good thing, however, is that many of these problems are fairly simple to fix and would often resolve after some DIY troubleshooting. If you are having trouble with your pressure washer, here is a guide on how to troubleshoot some common problems that you might find useful.

Why is My Pressure Washer Not Spraying?

If the pump Runs but there is no spray pressure this can be due to several possible reasons:

  1. Water is turned off
  2. Turn water on.
  • Nozzle is plugged
  • Clean or replace with proper size.
  • Inlet chemical injection valve is open, without the end of the pickup tube inserted into the detergent. (upstream injection systems only)
  • Close soap valve or submerge detergent pickup tube into solution.
  • Coil on hot water machines is obstructed
  • Clean obstruction or scale deposits from the coil using coil cleaner.
  • Pump is dry, needs to be primed.
  • Crank open fitting on the high pressure outlet of the pump until water flows out.

Why is My Pressure Washer Not Building Pressure?

If the motor starts but there is no build-up of pressure, this may be due to the following reasons:

  • The water filter could be clogged. Check the water filter and clean if needed.
  • There is no water. Check that the water supply is turned on and that there is no air in the supply hose.

Pressure Washer Low Operating Pressure

Low operating pressure may be due to several reasons. Identifying the root cause is the first step to fixing the problem.

To troubleshoot your machine when there is low operating pressure, check the following:

  1. The pressure gauge could be faulty.
  2. Install a new gauge.
  3. Water supply is insufficient.
  4. Use a large water supply hose; clean the filter at water inlet as it might be clogged.
  5. Plumbing or hose leak.
  6. Check your plumbing system for leaks. If present, retape leaks with Teflon tape.
  7. Belt slippage
  8. Tighten or replace belt. Be sure to use the correct belt.
  • Faulty or misadjusted unloader valve.
  • Adjust unloader for proper pressure.
  •  Install repair kit or replace when needed.
  • Worn packing in the pump.
  • Install new packing kit.
  • Fouled or dirty inlet or discharge valve in pump
  • Clean inlet and discharge valves.
  • Obstruction in spray nozzle
  • Remove the obstruction.
  • Leaking pressure control valve
  • Rebuild or replace as needed.
  1. Slow engine RPM.
  2. Set the engine speed at proper specifications.
  1. Pump sucking air.
  2. Check the water supply and possibility of air seepage.
  1. Faulty unloader valve seat.
  2. Check and replace if necessary.
  3. Valves sticking.
  4. Check and clean or replace if necessary.
  1. Machine has been stored in freezing temperatures
  2. Thaw out the machine completely, including the hose, spray gun and wand.

What Does the Unloader Do on a Pressure Washer?

Pressure washers are built with one of two types of unloaders: The Trapped Pressure Unloader or the Flow Actuated Unloader. After the pump is filled with water, the direction of water flow must be controlled with the unloader or regulating valve. A positive displacement pump is always delivering a specific volume of water whether the spray gun is open or closed; therefore a device is needed to control the direction of flow, either to the open spray gun or redirecting the flow back to the inlet side of the pump when the spray gun is closed.

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Without an unloader valve, dangerously high pressure will be produced when the spray gun is closed because the water being forced out of the pump has no place to go. The unloader is used as a safety device to prevent the development of dangerously high pressure and guard against the failure of component parts.

Pressure Washer Unloader Valve Symptoms

Using an unloader beyond its recommended settings and up to the maximum ratings will yield a shorter service. Like any other mechanical part, unloaders ultimately wear out.

Many unloader valves issues are associated with the quality of the water being used. Small solids like sand grains are very abrasive and damage the metal seal in unloader valves, allowing more water to be bypassed, resulting in less flow through the nozzle. Another thing that is commonly associated with an unloader valve failure is multiple gun applications. Each time a gun in the system closes the unloader valve needs to bypass the excess of water, so every gun in the system increases the number of unloader cycles and the possibility of failure.

Common symptoms that indicate you need to replace the pressure washer unloader valve include:

  • The thermal release valve opens and sprays steam water from the pump. This happens when the unloader valve clogs or sticks shut.
  • Nozzle water pressure decreases quickly after you press the wand trigger. This sysmptoms occurs when the unloader valve sticks open.
  • The engine stalls when you are not using the wand. When pressure builds up in the pump because the unloader valve is not opening as it should, the engine cannot continue to turn the pump shaft so the engine dies.

A failed unloader valve can also cause high pressure at the nozzle. The unloader valve recirculates water to the pump inlet when the pump is running but the spray and is not in use. If the unloader valve sticks shut, outlet water pressure builds up until you trigger the spray wand or the pressure relied on valve trips to release excess pressure. If you see pressure washer unloader valve symptoms that indicate a failure such as excessive spray and pressure and relief valve tripping, replace the unloader valve.

How to Replace a Pressure Washer Unloader Valve

If the pressure washer unloader valve is not working, replace it with the manufacturer-approved part. The unloader valve kit includes the O-ring and all parts needed for the repair.

To replace a Snapper, Briggs & Stratton, Troybilt, Husqvarna, or Craftsman pressure washer unloader valve, follow these steps:

  1. Pull the spark plug wire off the spark plug on the pressure washer engine.
  2. Use an open-end wrench to turn the unloader valve counterclockwise to remove.
  3. Install the O-ring from the kit on the new unloader valve.
  4. Lubricate the O-ring on the new unloader valve with silicone lubricant.
  5. Thread the new unloader valve into the pump and tighten. If you have a torque wrench, tighten the new unloader valve 10-12 ft.-lbs.
  6. Reconnect the spark plug wire to the engine.
  7. Start the pressure washer and check for water leaks at the new unloader valve. Make sure that the new unloader valve works properly.

Pressure Washer Not Spraying Hard

If your pressure washer pump runs but has low spray pressure, this may be due to several possible causes:

Nozzle orifice is obstructed

If so, follow these troubleshooting steps:

  • Shut off the engine
  • Purge air from the pump
  • Remove the orifice from the adjustable nozzle or remove the spray tip from the nozzle extension
  • Clean the orifice or spray tip using the wire tool from the maintenance kit.

Leaky high-pressure hose

  • Check the O-rings. If damaged, remove old O-ring with a small flathead screwdriver, and replace with new one.
  • Leaky spray gun
  • Replace the pressure washer spray gun with a new one.

Water inlet or filter screen is blocked, clogged or damaged

  • Disconnect the garden hose from the water inlet; clean the water inlet and filter screen.
  • If screen is damaged, remove damaged screen and insert new screen.
  • Supply water temperature over 100oF
  • Provide cooler water supply.

Supply water pressure and flow rate is inadequate

  • Test the supply water using a pressure/flow rate gauge.
  • If the supply water does not produce a minimum of required pressure and flow rate for the unit, look for an alternative source than can provide adequate pressure and flow.

Faulty pump

To troubleshoot:

  • With the high pressure hose removed from the pump, attach the garden hose and turn on water.
  • Water will flow through the pump, now turn on the engine. The water flow should increase in pressure and length from where it exits the pump.
  • If the water flow does not increase in pressure and length, there is an internal pump issue.
  • If water flow increases in pressure in length then there is likely a clog in one of the attachments; high pressure hose, gun, wand, or nozzle.

Low pump oil level

  • If so, add oil to the pressure washer pump.
  • Worn or wrong size nozzle
  • Replace nozzle of proper size.

Belt slippage

  • Tighten or replace with correct belt.

Worn or improperly adjusted Unloader valve

  • Install pressure gauge on pump head to adjust pressure.
  • Check valve seat on Unloader.

Air leak in inlet plumbing

  • Reseal fittings and inspect inlet hoses for air leaks.

Electric Pressure Washer Motor Won’t Start

If the electric motor does not start, this may be due to several possible causes:

  1. There is no electric power. Check the cord, plug, socket, and breaker to make sure there is power going to your electric pressure washer. Repair or replace any faulty part, if needed.
  2. The thermal overload in the motor or starter has been tripped. If this is the case, you need to reset manual overload, typically by depressing the thermal switch on the outside of the motor or starter after the motor has cooled.
  3. Inoperative power switch. Check the power switch.
  4. Electric motor or wiring failure. To fix this, you may need to repair or replace motor and/or wiring.
  5. No water pressure at inlet. Connect to appropriate water supply.

Pressure Washer Surging

Pressure surging is a common condition when using a pressure washer. That is, when the trigger is pulled, pressure is satisfactory for a while then falls off. When the trigger is released, pressure builds up to normal levels.

Generally, when pressure surges it is a sign that the water supply cannot provide the flow rate required by the pump.

To fix this issue, there are several possible solutions you can try:

  1. Make sure the supply is not restricted. Check to make sure there are no under-sized fittings and the inlet screen is not obstructed.
  2. Make sure the flow rate of the water supply is sufficient for the pump. First, establish your pump’s capacity, like in gallons per minute (gpm). Then determine the flow rate of your supply by measuring the gallons that can be delivered in one minute. Do not use the pump if your supply does not deliver the flow rate your pump requires. Otherwise, it will suck air, leading to cavitations which can cause damage to the pump components.
  3.  Check for leaks in the supply fittings. Any leak will cause the pump to draw air and perform poorly.

Pressure Washer Not Siphoning Detergent

If your pressure washer is not drawing detergent, it may be due to the following reasons:

There is an air leak

  • Make sure you tighten all clamps.
  • Check detergent lines for holes.

The filter screen on detergent suction hose is plugged

  • Clean or replace the filter screen.
  • Run warm water through the filter to remove debris.

Incorrect nozzle or adjustable nozzle is in the wrong position

  • Make sure you install chemical/detergent nozzle or push adjustable nozzle forward (away from gun).

Detergent filter valve is at lowest setting

  • Set detergent filter valve to a higher setting.

Dried up detergent plugging the metering valve injector

  • Disassemble and clean thoroughly.

Low detergent level

  • Check the detergent level. Add detergent, if needed.

High viscosity of the detergent(too thick)

  • Dilute the detergent to specifications.

Damaged or clogged detergent suction tube

  • Remove obstruction or replace detergent suction tube.

Pump is Noisy

If there is a loud noise coming from the pressure washer pump, this is often a sign that the pump is sucking air.

Check that hoses and fittings are air-tight. Turn off the machine and purge the pump by squeezing the trigger gun until a steady flow of water emerges through the nozzle.

Engine Operates for 15 Minutes then Stops

There could be several possible causes for this problem. To fix, check the following:

  1. Not enough gas or engine oil
  2. Fill the tank with gas.
  3. Check oil level.
  4. Vapor lock developed by heat of day
  5. Keep gas tank full to avoid vapor locking
  6. Obstruction in fuel filter
  7. Clean or replace fuel filter.

Fluctuating Pressure

If the pressure fluctuates, this may be due to several possible causes:

  1. Worn or dirty pump valves
  2. Nozzle is obstructed
  3. Blow out or remove debris with fine needle.
  4. Pump sucking air, inlet hose leaking
  5. Check that all hoses and fittings are airtight. Turn off the machine and trigger spray gun until a steady flow of water flows through the nozzle.

Insufficient water supply

  • Turn water on full force.
  • Check garden hose for kinks, leaks or blockage.

Leaking H.P. seals

  • Replace seals.
  • Leaking L.P. seals
  • Pressure feed the pump and replace L.P. seals if water leaks from the pump head.

How to Apply Chemicals/Cleaning Solvents

Applying chemicals or cleaning solvents is a low-pressure operation. Be sure to only use soaps and chemicals designed for pressure washer use.

To apply chemicals:

  1. Ensure chemical siphon hose is attached to barbed fitting location near high pressure hose connection of pump.
  2. Place the end of chemical siphon hose with filter on it into container holding the chemical/cleaning solution.
  3. Install low pressure(black) nozzle into quick connect fitting of spray wand.
  4. Some units have a soap control valve. If equipped, turn the valve counterclockwise to increase the soap output and clockwise to decrease the soap output.
  5. After use of chemicals, place chemical siphon hose into a container of clean water and draw cleaning water through the chemical injection system to rinse system thoroughly. If chemicals remain in the pump, it could be damaged.

How to Clean and Maintain a Pressure Washer

Before cleaning, maintenance, or storing, make sure that the pressure washer ON/OFF switch is in the OFF position, the power plug is removed from the electrical supply, the water supply has been turned off, the water hose is disconnected and any residual pressure in the lance and high-pressure hose has been released.

Cleaning

Yard Force Model EW U15

  • Wipe the pressure washer with a slightly dump cloth. Do not clean the pressure washer using a high pressure water jet.
  • Clean the water filter
  • Remove water inlet adapter to get access to the filter.
  • Remove the filter.
  • Rinse filter until it is free of debris or blockage.
  • Replace the filter and inlet adapter.

Total Model TGT11356, UTGT11356

  • Clean the sieve in the water connection regularly:
  • Remove coupling from the water connection and rinse with warm water to prevent any foreign matter from clogging the pump.
  • Pull the sieve out using flat pliers.
  • Clean the sieve under running water.
  • Reinsert the sieve into the water connection.
  • Clean the nozzle with the needle clean-out tool provided:
  • Remove the spray wand from the gun.
  • Remove any dirt from the nozzle hole and rinse.

Maintenance:

Attention to regular preventative maintenance procedures will help in preserving the performance of your pressure washer.

Below are some useful maintenance tips for your Simpson pressure washer:

  1. Engine oil
  2. Inspect daily
  3. Change engine oil after first 10 hours, then every 50 hours especially in high ambient temperatures
  4. Pump oil
  5. Inspect daily
  6. Change the pump oil after first 25 hours, then every 3 months for 150 hours.
  7. Belts
  8. Tighten every 6 months.
  9. Inspect/replace annually.
  • Replace spray nozzle every 6 months.
  • Replace fuel lines annually
  • Clean fuel tanks annually
  • Clean water screen/filter weekly.

Spray Wand Maintenance (Briggs and Stratton):

Prior to use, always test the spray gun to make sure it works properly. Start by making sure the hose connection to the spray gun is secure, then test the spray gun assembly by pressing and releasing the trigger. The trigger should spring back into place when released.

Next, engage the safety latch, and test the trigger. You should not be able to depress it. If the trigger is loose, or can be depressed while the safety latch is engaged, or water is leaking around the gun handle, replace the spray gun immediately.

Step 1- Shut the engine off and turn off the water supply. Depress the spray gun trigger to relieve the pressure in the system. Detach the wand from the spray gun. If you have an adjustable nozzle, twist the nozzle to STREAM, then remove the nozzle orifice using a 2mm (or 5/64) Allen Wrench. If you have Quick-Connect spray, simply remove the spray tip from the nozzle.

Step 2-Use a paper clip to free any foreign material clogging or restricting the orifice or spray tip.

Step 3- Flush water through the nozzle for one minute to remove debris.  For an adjustable nozzle, turn the nozzle to STREAM and move from low to high-pressure mode while flushing. Reinstall the orifice into the adjustable nozzle (don’t over tighten), or install the spray tip into the nozzle, then reconnect the wand to the spray gun and test to make sure the nozzle works properly.

Storage:

Yard Force Model EW U15

  1. Disassemble the lance and spray gun.
  2. Remove the hoses from the pressure washer.
  3. Drain any residual water from the high pressure hose, lance, spray gun and pressure washer.
  4. Wipe all components down with a soft dry cloth.
  5. Store the pressure washer in a dry well ventilated area out of reach of children.

Total Model TGT11356, UTGT11356

  1. Park the machine on an even surface
  2. Detach spray lance from the trigger gun.
  3. Push the disconnect button on the trigger gun and pull the high-pressure hose out of trigger gun.
  4. Place the trigger gun into the storage for the trigger gun.
  5. Put both spray lances into the storage for the spray lance.
  6. Dirt grinder spray lance: Nozzle towards the bottom.
  7. Coil the high-pressure hose and hand it over the hose storage.
  8. Store the mains connection in the accessory compartment.
  9. Always store the pressure cleaner, parts, and accessories in a place that is inaccessible to children. The ideal temperature is between 10oC and 30oC. Store the power washer indoors to prevent the water in the unit from expanding under freezing conditions.

Pressure Washer Not Pulling Soap (Simpson Pressure washer)

If inlet injection will not siphon soap, check the following:

  • Check valve if strainer is clogged. If it is, clean or replace. Rinse after each use.
  • Check whether chemical valve is closed or is clogged. Open chemical valve or clean as needed.
  • Check whether strainer is submerged in solution. If not, be sure to submerge strainer and replenish chemical.
  • Check if the detergent hose is cut or kinked. Inspect the hose, replace as necessary.

If downstream injector will not siphon soap, this may be due to several reasons:

  • Adjustable knob on injector is closed (where applicable). Open by turning counter clockwise.
  • The unit is not in low pressure mode. Open dual wand or install low pressure (black) nozzle.
  • Detergent hose is cut or kinked. Inspect the hose and replace as necessary.
  • Chemical strainer is plugged or is not submerged. Check the screen on strainer pickup tube.
  • Internal injector parts are corroded or stuck.  Disassemble, clean or replace.
  • Outlet water temperature is too high. Use with cold water (150o Maximum)

Pressure Washer Not Staying On

If your pressure washer is not staying on, it may be due to several possible causes:

  1. There is not enough gas or engine oil
  2. Fill tank with gas.
  3. Check oil level.
  4. Vapor lock developed by heat of day
  5. To fix this, keep gas tank full to avoid vapor locking.
  6. There is an obstruction in the fuel filter
  7. To fix, clean or replace fuel filter as necessary.

How to Use Soap with a Pressure Washer (Total Model TGT11356, UTGT11356)

Detergent can only be added when the device is operated in low pressure.

When using detergents, the material data safety sheet issued by the detergent manufacturer must be adhered to, especially the instructions regarding personal protective equipment.

  • Remove the cap of the clean detergent bottle.
  • Gently pull the onboard detergent tank out of its storage position.
  • Fill the tank with detergent designed specifically for use with pressure washers.
  • Push the detergent bottle with the opening pointing downwards into the connection for the hose clean detergent.

The recommended cleaning method is as follows:

  • Spray the detergent sparingly on the dry surface and allow it to react, but not to dry.
  • Spray off loosen dirt with the high pressure Met.

After operation with detergent:

  • Remove the hose clean detergent bottle from the intake and close it with the lid.
  • For storage, put the detergent bottle into the retainer with the cap pointing up.

How to Change Pressure Washer Nozzles

Karcher Pressure Washer

  1. Switch off the pressure washer by turning the power dial to “0” position.
  2. Twist the nozzle where it meets the trigger handle counterclockwise, which detaches it from the pressure washer.
  3. Insert the new nozzle into the trigger and turn it clockwise, which locks it into place.
  4. Turn the pressure washer back on and your new nozzle will be ready to use.

Ryobi Pressure Washer

To replace the turbo nozzle on a Ryobi pressure washer:

Step 1: Remove the turbo nozzle

  • Pull back the quick-release collar on the coupling.
  • Remove the nozzle from the wand.

Step 2: Install the new turbo nozzle

  • Apply a small amount of silicone grease to the fitting on the new turbo nozzle.
  • Pull back the quick-release collar on the coupling.
  • Install the new turbo nozzle onto the wand.

How Much PSI Does a Pressure Washer Generate?

Gas-powered models typically put out 2,000 to 2,800 PSI of pressure compared with 1,300 to 1,700 PSI for electric models.

How Do You Know If Your Pressure Washer is Bad?

Several indicators will show that a pressure washer is bad/faulty. The most common is a leak, pulsating output pressure, and low output pressure.

Leaks are often caused y a damaged or worn seal. A leaking indicates a worn O-ring or gasket. To fix the leak, replace the old gasket with a new one.

A leaking cylinder head or inlet/outlet elbow is often caused by frozen water inside the pump. You should always drain all water in the pump before winter starts. Otherwise, it will expand and damage the plastic parts.

If you get a pulsating out pressure, this indicates that there is not enough water in the pump.  In the case of an electric pressure washer, this causes motor restarts. Remove the inlet filter and clean any blockages. If this is not causing the issue, there could be a blockage in the pump, or a leak from the cylinder head can also cause the pressure to pulse.

Low pressure, on the other hand, is generally due to worn O-rings or a dirt blockage at the pump inlet. To fix the issue, replace the O-ring. If the O-ring is not the problem, the low pressure could be due to dirt blockage. To restore the machine’s pressure, clean the filters and remove the dirt and debris that prevent the adequate supply of water to the pump.

How Do I Know If My Pressure Washer Gun is Bad?

If you cannot shut off the water from the trigger wand and there are no known issues with the unloader valve, there is likely a problem with the wand itself. The trigger wand has a mechanism inside of it so that when the trigger is released, the flow of water is blocked.

The spike in pressure created prompts the unloader valve to switch into bypass mode. If the seal that stops the flow of water through the wand is broken, water may continuously flow from the nozzle, as the unloader valve will not switch into bypass mode as it should.

How Do I Check the Pressure on My Pressure Washer?

You need to install a pressure gauge to check the pressure on your pressure washer. A pressure washer gauge is used to measure the water pressure generated by a pressure washer pump. These gauges can have a pressure scale of over 2,000 bar (29,007 PSI).

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They are usually installed at the pump outlet to measure to measure the outlet pressure, which is the pressure in the hose. They can also be installed at the suction of the pump to measure the inlet pressure.

The following are some of the functions of a gauge on a pressure washer:

  • To measure the pressure levels of the pump.
  • It can show an indication of damage to the pump internal components.
  • It is used in calibrating the pressure washer pump operations.
  • It serves as a visual confirmation when the pressure level is changed.
  • When installed at the suction side of the pump, the gauge can help indicate the onset of cavitation.
  • Indicates potential leakages in the hose or the housing of the pump.

Oscar

In his spare time, Oscar loves tinkering with electronics. Solar panels, wiring, old TVs and sometimes DIY powerwalls. When he is not busy trying not to electrocute himself, you can find him in the garden tending to his vegetables and chickens.

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