Gas binding fault (GBF) represents a critical operating condition in centrifugal pumps, characterized by severe performance degradation due to gas–liquid interactions within the flow passages. To elucidate the underlying mechanisms, this study employs a coupled Lattice Boltzmann Method and Large Eddy Simulation (LBM–LES) framework to analyze the hydro–mechanical-electrical behavior of a centrifugal pump under varying inlet gas volume fractions (IGVF, β). It is shown that, at low gas content (β ≈ 3%), dispersed bubbles primarily accumulate along the blade suction surface and near the impeller outlet. As β increases to 6%, gas structures migrate toward the impeller hub, with partial transport to the outlet where gas-liquid separation becomes evident. Further increases in β promote coalescence into larger gas clusters, progressively obstructing the flow channels and intensifying flow instability. The evolution of characteristic performance indicators reveals a clear dependence on both gas content and operating conditions. At low flow rates, these indicators vary monotonically with β, whereas at higher flow rates they exhibit pronounced fluctuations, reflecting enhanced unsteadiness. In particular, the pressure coefficient remains relatively stable for β below 6%, corresponding to a non-gas-binding regime. Beyond this threshold, it decreases sharply, marking the onset of gas binding.