1) First of all, never attempt to diagnose any problems if your pressure wash is still hot. You must give it time to cool after use or you could severely burn yourself. Be sure to release the pressure in the pressure washer by triggering the gun after the engine has completely stopped.
2) Always remove the spark plug of gasoline engines before making any adjustments to pressure washer equipment or before attempting to diagnose any problems with your pump. Whenever there's doubt as to what the problem may be, or if you have apprehension in dealing with your pressure washer, contact a professional.
3) Excessive vibrating from the pump - this could indicate there's an air leak in the pressure washer pump or there's a clogged water filter. It could also suggest the valves are dirty or clogged. Check to endure there are no leaks and that filters are clean and free from debris.
4) Low pressure - This could mean a number of things. If you feel low pressure in your pressure washer, your water supply may be insufficient. It could also mean a problem with the valves, unloaders, or even the power supply. Pump valves may also be dirty. Also check the unloader valve and the EZ start valve to ensure they're not worn. If they appear worn out, they'll need replacement.
5) Fluctuations in power levels - This can indicate a leak in the water supply. Also be sure to check spark plugs, pump valves, and engine valves for both dirt and wear. They may need cleaning or replacement.
6) Pulsations in the pump - This can indicate a number of the problems above, but also possibility of burned engine valves or excessive pump pressure as the engine begins to load. You'll want to be sure to check these. If you're unsure.
7) Engine won't start - Check to see if there's gas in the tank. Also check to ensure there's adequate oil. If gas and oil are sufficient, switch the on and off button. Check the supply valve to be sure that it's turned on as well. The engine could be choked or flooded. Check to be sure spark plugs aren't dirty or worn out.