April 1, 2013

How to replace a pressure washer pump

By Lyle Weischwill
How to replace a pressure washer pump

This DIY repair guide explains how to replace a pressure washer pump. The pump creates the water pressure for the spray nozzle. Air in the inlet water supply can damage the pump, as can detergent residue left in the pump. If a damaged pressure washer pump is causing low pressure at the nozzle, replace the pump with the manufacturer-approved replacement part.

This basic procedure works for Craftsman, Briggs & Stratton, Snapper, Troybilt, Husqvarna and Generac pressure washers.

Quick links
Tools required
Wrench set
Allen head bit set and ratchet
Pipe thread sealing tape
Work gloves
Repair difficulty
Time required
30 minutes or less
Repair difficulty
Time required
30 minutes or less

Instructions

  1. 01.

    Disconnect the spark plug wire

    Disconnect the spark plug wire from the spark plug.

  2. 02.

    Disconnect the hoses attached to the pump

    Remove the inlet water hose from the pump, if attached.

    Remove the nozzle hose from the pump.

    Clamp the chemical injection tube if the tube has fluid in it. Pull the chemical injection tube off of the chemical injection inlet valve.

    Clamp off the chemical injection hose.

    Clamp off the chemical injection hose.

    Pull the chemical injection hose off of the valve.

    Pull the chemical injection hose off of the valve.

  3. 03.

    Remove the pump

    The pump is attached to the bottom of the pressure washer by 3 Allen-head bolts.

    Loosen but don't remove the Allen-head mounting bolts that secure the pump to the engine.

    With the pressure washer upright, support the bottom of the pump while removing the Allen-head mounting bolts from the pump.

    Pull the pump off of the engine crankshaft or allow the pump to drop down and off of the crankshaft to remove the pump from the engine. 

    Loosen the pump mounting bolts.

    Loosen the pump mounting bolts.

    Remove the pump.

    Remove the pump.

  4. 04.

    Prepare the new pump for installation

    Transfer the thermal relief valve from the old pump to the new one.

    Use pipe thread sealing tape to seal the thermal relief valve connection.

  5. 05.

    Install the new pump

    Rotate the notch in the pump drive connection to align the notch with the key on the engine crankshaft.

    Slide the pump onto the engine crankshaft.

    Rotate the pump to align the mounting holes.

    Reinstall the Allen-head mounting bolts and tighten them securely.

    Install the new pump.

    Install the new pump.

  6. 06.

    Reconnect the hoses on the pump

    Reconnect the chemical injection tube on the chemical injection inlet valve.

    Remove the hose clamp from the chemical injection hose, if used.

    Reconnect the nozzle hose connection and the inlet water hose connection on the pump.

    Reconnect the chemical injection hose.

    Reconnect the chemical injection hose.

  7. 07.

    Reconnect the spark plug

    Reattach the spark plug wire.

  8. 08.

    Test the new pump

    Start the pressure washer and test the new pump.

Warning: Undertaking repairs to appliances can be hazardous. Use the proper tools and safety equipment noted in the guide and follow all instructions. Do not proceed until you are confident that you understand all of the steps and are capable of completing the repair. Some repairs should only be performed by a qualified technician.

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: faulty unloader valve, bad pressure regulator
Main causes: damaged recoil starter, oil inside cylinder, locked up engine piston
Main causes: stale fuel, gummed up carburetor, engine needs tune up, throttle and choke controls need adjustment, bad recoil starter
Main causes: overfilling engine with oil, improper fuel/air mixture, choke system problems, dirty carburetor, engine needs tune up
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 replace a pressure washer unloader valve

The unloader valve recirculates water to protect the pump from damage. If the unloader valve is defective, replace it using the steps in this repair guide.

Repair difficulty
Time required
 15 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
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

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.

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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.