i had the tank off my safari glx. i put some degreaser called Orange. i had some water in with it, i let it soak inside for about 30 min or so. i then took my power washer and washed it out real good then i hung the tank up side down filler neck to the bottom and let it sit for a couple days. well when i got back i found some tar like stuff inside my tank. it was kind of sticky. what is this stuff and how do i get rid of it? Thanks!