I'm sure there are LOTS of accidents where the engine keeps running after impact. That's why car manufacturers use impact sensors to shut off the fuel pump. As I said above, you can completely sever a return line or partially sever a pressure line and still have fuel pressure. My in-tank fuel pump is rated at 255 LPH (67 GPH or 1.12 GPM) at EFI operating pressure and that translates to a pretty big leak with the engine idling.