Gas Pressure Washer: Weak spray
An insufficient water supply can cause low pressure at the nozzle. Check the water pressure at the source and the flow connected to the inlet of the pressure washer. Check the inlet screen for a clog that could be blocking inlet water flow.
Check whether a low-pressure spray tip is installed on the wand; if so, install a different nozzle. A problem with the wand or pressure hose can also cause low nozzle pressure. Clean or replace the wand if necessary. Replace the pressure hose if it's clogged.
A pump failure can cause low nozzle pressure. Replace the pump check valves or replace the entire pump if it doesn't build up adequate spray pressure. A stuck unloader valve can also cause low pressure at the nozzle. Replace the unloader valve if it sticks open and constantly recirculates water back to the pump inlet.
Replace the pressure washer pump check valves
The check valves are spring-actuated pump valves that allow water to flow in one direction from the pump inlet to the pump outlet. If the check valves are worn out or defective, the pressure washer won't spray. Inspect the pump check valves and replace them if worn or defective.
Replace the pressure washer pump
The pump creates the water pressure when the engine is running. If the pump isn't developing any water pressure, replace the pump assembly.
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.
Replace the pressure washer pressure hose
If the water pressure hose leaks at the fittings, check each fitting for proper tightness. If you can't tighten the fittings, replace the pressure washer hose. Also replace the hose if it is split or damaged.
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.
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.
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.
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