The use of finite element modeling (FEM) tools is part of the most of the current product development projects of the automotive industry companies, replacing an important part of the physical tests with lower costs, higher speed and with increasing accuracy by each day. In addition to this, computer-aided engineering (CAE) tools can be either used after the product is released, at any moment of the product life, in many different situation as a new feature release, to validate a more cost-efficient design proposal or to help on solving some manufacturing problem or even a vehicular field issue. Different from the phase where the product is still under development, when standard virtual test procedures are performed in order to validate the vehicle project, in this case, where engineers expertise plays a very important role, before to proceed with any standard test it is fundamental to understand the physics of the phenomena that is causing the unexpected behavior. This understanding will make possible to find the problem root cause, allowing to virtually testing a wide number of different solutions in a short time. In this paper a vibrational transfer function (VTF) simulation is used on a trimmed body FEM model to identify the root cause of a liftgate pumping issue, caused by a high relative displacement between the body frame and the belt line liftgate area, under a singular track excitation condition, that can be physically noticed and measured, but only deeply understood and properly fixed together with the use of FEM analysis.