This paper describes an investigation of the suitability of FE analysis using the virtual fluid mass (VFM) in fuel tank validation. It produces a mass matrix which represents the fluid coupled to a boundary consisting of structural elements and other effects, such as free surfaces, planes of symmetry and infinite fluids. The incompressible fluid produces a mass matrix defined with full coupling between accelerations and pressures on the flexible structural interfaces. This capability is used to model fuel tank with fuel filled inside. Hence, using the VFM method modal analysis is performed keeping the fuel tank 90% filled and results are compared with physical testing.The VFM method is much more reliable and accurate than the NSM or density adjusted method. The modal frequencies obtained in VFM technique are in proximity with the physical testing results. Further, the fuel tank and its mountings are evaluated for frequency response analysis with excitation in vertical direction.