Swinging for Divorce…

Can't say it'll work on your Dart, but with my riding mower, I turn off the fuel valve before shutting off the engine. I let it run for 1/2 - 1 minute before shutting off the engine. The purpose is to purge the carb bowl of fuel so when I go to start it again, it has about the right amount of fuel (works only when hot). If there were some way of using the fuel in the carb for practical purposes before turning off the key, it might enhance "fuel economy". Furthermore it might enhance your goals.