To keep the water output of an electric pressure washer stable, you should check and maintain the following:
Check the water inlet filter to ensure it is clean and not clogged.
Check the pump for any debris or build-up and clean as necessary.
Ensure the nozzle and other attachments are not blocked.
Check the hoses for any kinks or damage that may restrict water flow.
Check the pressure switch and unloader valve for proper operation.
Make sure the power supply to the cleaner is stable and the voltage is appropriate for the machine.
Consult the manual for specific troubleshooting and maintenance instructions for your specific model of high pressure cleaner.