Not sure how well a Flojet marries up to a Varistream, but it sounds as though the electronic pressure switch needs adjusting to a high cut-out pressure.
Secondly a Varistream seems to test the pressure drop on a programmed cycle. We have found this on the Mk1, Mk2 and now the digital versions. It does this by starting the pump and evaluating what current the pump needs to start pumping (as the pressure builds up the pump draws more amps). If the pressure is still there then it switches off for a while before starting the pump again.
We have taps on our poles. If you open the tap at the same moment the Varistream programme starts then we get a flow of water straight away. But if we open it a fraction later then we have to wait for what appears to be a life time before the start up programme cycle starts again and the pump starts.
Somebody once said it was a 15 sec cycle but I think its a lot less than that, probably 5 secs IMO.