wp_get_attachment_image_src always returns false

In function passing a attachment id or thumbnail id NOT post id.

Try this

<?php 

      global $post;
      $attch_id = get_post_thumbnail_id( $post->ID );
      $url = wp_get_attachment_image_src($attch_id);
      echo "<img src="".$url[0]."" />";

    ?>

I hope is useful.