Outdoor Power Equipment and Small Engines - Karcher elec pressure wash - no pressure - HELP plz

I have a two year old Karcher 3.97M. Mostly I get no pressure. Sometimes when I pull the trigger on the wand I'll get some then none. The pump runs then stops runs then stops constantly. I disassembled it and from what I can see it all looks normal at least nothing obvious. I have cleaned the input screen and there is plenty of pressure. The wand is not the problem since I do not get any pressure with or without it. There are no leaks. I turned it on and watched a small handle that is connected to the switch constanly moving back and forth. Some sort of pressure control. Can I disassemble this part or replace it? Any and all suggestions appreciated. TIA!!!

Does any water at all come out? The same amount as would come out of the water hose? Less? A trickle?

Thanks for your reply. Yes water comes out at about the same pressure it goes in. In my first post I should have said that I only get full pressure washer pressure the first time I pull the trigger then it goes to normal pressure. Could there be some sort of internal leak that I cannot detect or could the pressure regulator be faulty? How can I know? Can this be repaired?

How is your supply pressure? Sounds like either the supply is too low, there is a restriction in the outlet side of the pump, or the pressure switch actuator is defective.

I have an intermittent "no pressure" problem with my pressure washer. I keep squeezing the trigger until it will suddenly have pressure and then work normal, otherwise it just dribbles. Do you think this is a pressure switch problem, and is this switch a mechanical type or electrical selonoid type or ??? Took to a repair shop, they wanted $350 to replace the pump, I did not bite.

I have no idea, as I don't know if you have an electric or gas unit, or any other info about it. Assuming it's gas, and assuming it's one of the lower-end washers with the engine over the pump, then I'd say the unloader is bad (very common failure for these type pumps) and the reason they want to replace the whole pump is because sometimes the unloader can't be removed without destroying the pump. That's my best guess.

Sorry...should have included more info. but yes it is a gas powered, Honda engine from Home Depot, 2200 psi was ~$600. A couple of years ago, same problem, and the repair facility "cleaned" out the pump and it has worked good since then but now same problem. I do not know if calcium build up or what ever is the problem. Not being familiar with and uploader and how to take it apart etc. i would unknowingly think that I could buy a new pump and replace it less than $300 ?? Thanks for your comments.

Ok, this may be different from my assumption...is the pump aside the engine instead of under it? If so, you probably have a cat pump, or at least one of similar style. The unloader should be accessible and easily cleaned to get it to stop hanging up and causing your loss of pressure. It is usually in the valve body of the pump.

Thanks for your reply. Is the pressure switch actuator the piece that is attached to the on/off switch?

I don't have a diagram of you washer, so I'm not sure where it is, but it is what turns the switch on and off. I'd guess it was a mechanical valve attatched to the pump with a linkage going to the switch.