Joe, my guess is the same as this. So with a mechanical fuel pump, cranking the motor is how it works (when the motor is off). If your car sits for any more than a day or 2, the gas likely evaporated from the carb. That means you gotta crank it and crank it for the fuel to pump into the carb and THEN it starts. Obviously if you drove it earlier that day, it's full of fuel already.