Preheat oven to 350 degrees and grease a 9 by 5-inch loaf pan.
In a large bowl, combine the flour, baking soda, cinnamon, and salt, set aside.
With a fork, mash 2 of the bananas in a small bowl so they still have some texture.
Beat the remaining 2 bananas and sugar together for about 3 minutes.
Add the melted butter, eggs, and vanilla to the banana/sugar mixture, mix well.
Mix in the dry ingredients just until they are incorporated, no need to over-mix.
Fold in the pecans and the mashed bananas.
Pour the batter in the loaf pan, and give it a rap against the counter to remove any air bubbles.
Bake for about 1 hour and 15 minutes, until golden and a toothpick inserted into the center comes out clean. Don't worry if the bread develops a crack down the middle, it's common and won't hurt a thing!
Let cool for about 10 minutes in the pan, then turn out onto a wire rack to cool completely.