One way is to put a trap in the suction so the pump doesn't drain when it's stopped.
Of course, you still need a big vacuum pump or other means to prime the pump for a black start. See documentation for the New Orleans pumps, the subject of much discussion here in the past year. Since you must have the vacuum pump, or a liquid priming pump, in place anyway, maybe you don't really need the big pump to be self- priming.
Mike Halloran
Pembroke Pines, FL, USA