2006 Chevy Cobalt fuel pump makes a spiratic whirring sound

There's a whirring sound coming from under my cobalt around the back tires. Seemingly from fuel tank area. It sounds like an electric motor making this noise. Maybe a problem with the fuel pump? Its a spiratic noise that has no pattern, however I noticed that the exhaust has gaps in it that is synchronized with the whirring sound. You can feel these gaps when placing hand right behind exhaust pipe.