Karcher power washer pump won't restart after pressure built

[gt2003 18]

I inherited an electric Karcher power washer from my step Dad.  Obviously this isn't the machine for heavy duty use but for cleaning siding it works OK.  Here's the problem.  I connect and turn on the water, turn on the power switch and it will start the pump.  As long as I am using the wand and washing it works fine.  The pump keeps going and the pressure stays fine.  If I stop for maybe a minute or two, the pump shuts off and won't restart.  I can pull the trigger on the wand to release the pressure but still the pump doesn't come back on and there is very little water pressure.  Now, I can unplug and unhook the machine from the water overnight and the machine is good to go.  However, if I let it rest and build up pressure we are back to square one.  Very frustrating.  Please assist.  Thanks

[Beth n Rod 1,279]

I found this in a search:

 

http://forums2.gardenweb.com/discussions/1635728/karcher-1400ps-electric-pressure-washer-wont-work-please-help

 

Rod