Gas Pressure Washer: Engine losing power

The engine requires an adequate supply of clean air to run properly, so replace the air filter if it's dirty. The engine also needs clean, fresh gasoline, so replace the fuel in the gas tank if the fuel is older than 3 months. If the carburetor is gummed up, the engine loses power, so check the carburetor and rebuild it if necessary. Replace the carburetor if it's too dirty to clean.

If the engine starts and run fine for several minutes but then loses power, the unloader valve may have failed. A failed unloader valve won't recirculate water back to the pump inlet, so pump outlet pressure builds up, making it harder for the engine to run the pump. The engine bogs down when it struggles to run the pump.

Try this test to see if a bad unloader is causing the engine to lose power. Stop the engine and remove the nozzle from the tip of the wand. Start the engine and hold the wand trigger down so water flows freely out of the wand. If the engine continues to run smoothly instead of bogging down after several minutes, then you'll likely need to replace the unloader valve.

gas pressure washer

These repairs may help solve your gas pressure washer problem

Tune up the pressure washer engine

Tune up the pressure washer engine

A tune-up restores the pressure washer's engine to its peak operating condition. A tune-up includes changing the oil, cleaning the engine, replacing the air filter, checking the ignition system, inspecting the carburetor, adjusting the throttle and choke controls, and adjusting and lubricating all moving parts.

Replace the pressure washer carburetor

Replace the pressure washer carburetor

Over time, varnish from stale gasoline builds up in the carburetor, decreasing the amount of air/fuel mixture reaching the engine. Replace the carburetor if it's severely clogged with varnish or if the orifices are clogged with debris and can't be cleared using carburetor cleaner and compressed air.

Clean and rebuild the pressure washer carburetor

Clean and rebuild the pressure washer carburetor

Rebuild kits are available for most carburetors. The kit contains essential components such as jets, pins, seals and gaskets for overhauling the carburetor. You can sometimes fix a fuel supply problem by disassembling, cleaning and rebuilding the carburetor.

Symptoms for gas pressure washers

Choose a symptom to see related pressure washer repairs.

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: using a high-pressure spray tip when applying detergent, clogged siphon tube, chemical injection system failure
Main causes: damaged recoil starter, oil inside cylinder, locked up engine piston
Main causes: overfilling engine with oil, improper fuel/air mixture, choke system problems, dirty carburetor, engine needs tune up
Main causes: stale fuel, gummed up carburetor, engine needs tune up, throttle and choke controls need adjustment, bad recoil starter
Main causes: faulty unloader valve, bad pressure regulator
Main causes: broken recoil spring, damaged recoil starter
Things to do: tune up the engine, inject pump saver into the water pump when storing the pressure washer for the winter
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 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
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 install a pressure washer O-ring kit

O-rings seal fittings on the pressure washer pump. Damaged seals allow water to leak from the pump. Follow these steps to replace the O-rings in a leaking pressure washer pump.

Repair difficulty
Time required
 45 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.