The response of the autoparametric system consisting of an elastic structure and liquid sloshing in a cylindrical tank is investigated. The structure is subjected to a vertical sinusoidal excitation and there is an approximate relationship of the ratio 2 : 1 between the natural frequencies of the structure and liquid sloshing. The modal equations derived in the first report are used to examine the influence of the internal resonance ratio's deviation, or the detuning parameter. As a result, it is shown that amplitude modulated motions appear depending on the negative or positive value of the detuning parameter for high or low liquid level. The bifurcation analysis, Poincare maps and Lyapunov exponents show that amplitude modulated motions and chaotic oscillations can occur. In experiments the theoretical resonance curves were quantitatively in agreement with the experimental results.