Combine the chocolate chips, evaporated milk, and butter in a small saucepan. Cook over low heat, stirring constantly, until mixture is smooth and creamy. Combine the eggs, sugar, flour, salt, vanilla and pecans in a bowl and mix well. Gradually stir the chocolate mixture into the egg mixture, blending well, and pour into the unbaked pie shell. Bake in a 375 degree F. oven for 40 minutes or until the filling is set. Cool on a wire rack.