Filling the water tank after being dry and NOT having running water 
is normal.  Let the water sit for a while and try it again.  The air 
in the pump has to be displaced by water (primed) for the pump to 
begin doing what it is supposed to do.  The pump should be start 
pumping water by the time you read this.  It only takes a few minutes 
for enough water to seep in there.

I've forgotten this more times than I care to admit!

Gunk in hoses that prevent water from getting to pump is also a 
potential cause.

- Jeff

- - - - - - - - - - - - - - - 
     Filled the water tank for the first time.  Tried to get water to come 
     out the faucet - nothing.  Turning off the engine, noticed the sound 
     of a pump running, but nothing coming out of the faucet still.  
     Manipulated the knob, and got the noise (obviously the pump) to stop 
     (why doesn't this run through the "master" switch on the front of the 
     sink/stove/fridge?)