I have a Sears Craftsman power washer (580.752060 - 2500PSI max and 2.3 gpm max) I have used it with no problems for the past several years and I trotted it out this morning to wash my deck - it fired right up and ran fine for about a half hour - plenty of pressure - no problems, when it suddenly lost all pressure. I checked for blockages, but there do not appear to be any - the hose and wand are all clear with no obstructions. When the water supply is connected, and I depress the trigger a stream of water appears (as it always does when I do that to relieve the pressure) - when I fire up the engine (Honda) it runs fine, but I get no pressure and when I depress the trigger in the wand I get no stream of water at all.
Any suggestions on an approach (other than tossing it!) would be appreciated.

Well being in the pressure washer business we call these "disposable" since they have a limited life time and are normally not worth fixing.

But some issues
1. air leaks on the low pressure side, causing it to suck air
2. if it has a chemical injection hose, it would could be sucking air into it
3. they all have a thermal or pressure relief valve on or near the pump, is there water coming out of any othe place besides the nozzle.
4. The pump uses packings and seals, after some time these have to be replaced. Often homeowners allow the unit to run for 3 or 4 minutes without holding the trigger down, this cuases heat to build up in a pump and will blow the seals
5. Just setting over the winter and not being used can cuase problems with the packngs and seals