Those little on-engine fuel pumps can exert a LOT of suction. The bottom of my fuel tank is several feet below the pump and it never had problems sucking the tank dry 
That said the suggestion for an electrical pump between the tank and the filters has a lot of merit. It also makes bleeding the filters after changing the element very easy.
That said the suggestion for an electrical pump between the tank and the filters has a lot of merit. It also makes bleeding the filters after changing the element very easy.