When you turn ignition, is there fuel pressured from the fuel filter housing to the rail, remove the pipe to check of course, if so then it has pressure, so can't see the need to prime unless it's got an air pocket, but not had that issue on these cars before, not like a poxy cmax we had many years ago, that needed the engine turning to create pressure, which wouldn't turn as it didn't have fuel pressure lol, now that was a huge ballache.