You cannot repair a damaged polypropylene gas tank with epoxy or a plastic tank repair kit, because gasoline will quickly dissolve the epoxy and the leak will reappear. Polypropylene is a thermoplastic, which means that you can use heat to melt the plastic and create a permanent repair in the polypropylene gas tank. To heat the polypropylene, you need to use a specialized tool that has a controlled heat output. This reduces the chance that you will scorch the surface of the gas tank, which will result in an ineffective repair.
Drain the gasoline from the polypropylene gas tank and remove the damaged polypropylene gas tank from the vehicle, per the vehicle’s repair manual, with the mechanic’s tool set.