April 01, 2013

How to replace a pressure washer pump

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 gas pressure washer part.

This procedure shows Craftsman pressure washer pump replacement but the same basic process works for pump replacement on 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
15 minutes or less
Repair difficulty
Time required
15 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.

    PHOTO: Clamp off the chemical injection hose.

    PHOTO: Clamp off the chemical injection hose.

    PHOTO: Pull the chemical injection hose off of the valve.

    PHOTO: 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. 

    PHOTO: Loosen the pump mounting bolts.

    PHOTO: Loosen the pump mounting bolts.

    PHOTO: Remove the pump.

    PHOTO: 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.

    PHOTO: Install the new pump.

    PHOTO: 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.

    PHOTO: Reconnect the chemical injection hose.

    PHOTO: 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.

Things to do: tune up the engine, inject pump saver into the water pump when storing the pressure washer for the winter…

Main causes: broken recoil spring, damaged recoil starter…

Main causes: insufficient water supply, clogged water inlet screen, clogged pressure hose, faulty pump check valves, stu…

Main causes: overfilling engine with oil, improper fuel/air mixture, choke system problems, dirty carburetor, engine nee…

Main causes: damaged recoil starter, oil inside cylinder, locked up engine piston…

Main causes: dirty air filter, stale fuel, clogged or dirty carburetor, bad unloader valve…

Main causes: using a high-pressure spray tip when applying detergent, clogged siphon tube, chemical injection system fai…

Main causes: pump running for more than 5 minutes when the spray wand isn't being used, faulty pressure relief valve, ba…

Main causes: stale fuel, gummed up carburetor, engine needs tune up, throttle and choke controls need adjustment, bad re…

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

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 valv…

Repair difficulty
Time required
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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 t…

Repair difficulty
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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 t…

Repair difficulty
Time required
 45 minutes or less

Effective articles & videos to help repair your 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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