Gas Pressure Washer: Sprays too hard

A failed unloader valve can cause high pressure at the nozzle. The unloader valve recirculates water to the pump inlet when the pump is running but the spray wand isn't in use. If the unloader valve sticks shut, outlet water pressure builds up until you trigger the spray wand or the pressure relief valve trips to release excess pressure. Replace the unloader valve if excessive pressure builds when the spray wand isn't in use.

Some pressure washers have a pressure regulator that limits the water pressure. A defective pressure regulator can cause high pressure at the nozzle. Replace the pressure regulator if it doesn't regulate outlet water pressure properly.

gas pressure washer

These repairs may help solve your gas pressure washer problem

Replace the pressure washer unloader valve

Replace the pressure washer unloader valve

The unloader valve reduces water pressure within the pressure washer pump when the pump runs but the spray wand isn't used, by recirculating water to the pump inlet. If the valve sticks in the closed position, the thermal relief valve frequently discharges hot water onto the ground because the unloader valve can't open to allow recirculation. If the pressure washer doesn't develop adequate outlet pressure, the unloader valve could be stuck open. Replace the unloader valve if it sticks in either the closed or open position.

How to replace a pressure washer unloader valve

If your pressure washer suddenly loses all pressure, the unloader valve could be broken. This step-by-step repair guide shows how to replace a pressure washer unloader valve in less than 15 minutes.

Repair difficulty
Time required
 15 minutes or less
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Symptoms for gas pressure washers

Choose a symptom to see related pressure washer repairs.

Main causes: damaged recoil starter, oil inside cylinder, locked up engine piston
Things to do: tune up the engine, inject pump saver into the water pump when storing the pressure washer for the winter
Main causes: stale fuel, gummed up carburetor, engine needs tune up, throttle and choke controls need adjustment, bad recoil starter
Main causes: dirty air filter, stale fuel, clogged or dirty carburetor, bad unloader valve
Main causes: overfilling engine with oil, improper fuel/air mixture, choke system problems, dirty carburetor, engine needs tune up
Main causes: faulty unloader valve, bad pressure regulator
Main causes: broken recoil spring, damaged recoil starter
Main causes: pump running for more than 5 minutes when the spray wand isn't being used, faulty pressure relief valve, bad unloader valve
Main causes: insufficient water supply, clogged water inlet screen, clogged pressure hose, faulty pump check valves, stuck unloader valve
Repair guides for gas pressure washers

These step-by-step repair guides will help you safely fix what’s broken on your pressure washer.

How to install a pressure washer chemical injection kit

The chemical injection valve draws detergent into the pump. If it’s not drawing detergent, use a repair kit to replace the chemical injection valve.

Repair difficulty
Time required
 15 minutes or less
April 1, 2013
By Lyle Weischwill
How to replace a pressure washer pump

The pump can be damaged by air in the inlet water supply or by chemicals that remain in the pump body after using the chemical injection system. Follow these steps to replace a damaged pump.

Repair difficulty
Time required
 30 minutes or less
How to install a pressure washer check valve kit

Air in the inlet water supply can damage the check valves. If the pump won’t build up pressure due to damaged check valves, follow these steps to replace the check valves.

Repair difficulty
Time required
 120 minutes or less
Articles and videos for gas pressure washers

Use the advice and tips in these articles and videos to get the most out of your pressure washer.

March 1, 2016
Getting the most from a pressure washer
By Sears PartsDirect staff

Learn how to get the best results when using a pressure washer.

January 1, 2016
Choosing the correct spray tip for a pressure washer
By Sears PartsDirect staff

Spray tips vary in pressure and angle of spray. This guide matches the spray tip to the cleaning job.

November 1, 2015
7 steps for winterizing and storing a pressure washer
By Sears PartsDirect staff

Follow this advice to winterize your pressure washer.