The full faith and credit of the issuing corporation, and all taxable property within its limits, as constituted at the time of the issuance of such bonds, are, shall be, and must continue, pledged to the full and prompt payment of the principal and interest thereof. Should any tax for the payment of interest on any bonds issued under the provisions of this act at any time not be levied or collected in time to meet such payments, the interest on such bonds shall be paid out of the current expense, general expense or general fund of such issuing corporation, and the money so used for such payment of interest must thereafter be repaid to the fund from which so taken out of the first taxes collected for the payment of such interest.