Crushed & torn, or just imploded from a bad vacuum break ? Put a Schraeder valve in the cap and blow it up with regulated air pressure a few psi increase at a time. If you are worrying about blowing up your place, it's diesel. It would take more pressure to burst it than you have compressor for. Filling it partially with water will also relieve your anxiety, but now you have water in a fuel tank. Clamp off the drain line before the tank filter. The bowl is plastic.