I find that with 17mtrs of pole hose connected my pump wont prime unless I lay the pole on the floor and even then it takes ages. So I carry one of these:
I unplug the pole hose at the trolley and plug in the double male connector. This releases the valve in the waterstop connector on the trolley and takes out all the resistance in the hose. Turn the controller to full power and within a few seconds the pump's primed. Reconnect your pole hose. Job done.