Need advice as to how to pull water from under cabin water tank when city water is not available, as in off gridding. Pump works, battery is new, can hear pump humming away, but no water comes out of faucet. Was told that pump is self-priming. It works great when hooked up to city water. Hoses are air tight, all appears to be in order. Light work, refrig works, pump hums, tank is full of H2O, just no water. Suggestions?