On Fri, 11 Jan 2013 13:45:06 -0800, Oren wrote:

Test the sprayer near the house with just one hose. Use a homer bucket
for a soapy water... see if the venturi siphon is / starts working.

I did try that and failed - which is why I asked if I have to turn a
valve or something first.

But I didn't "prime" it, which is what it may need.