Custom Post Types Meta Content disappearing on updates

add_action('init', 'tours_register');

function tours_register() {

	$labels = array(
		'name' => _x('Tours', 'post type general name'),
		'singular_name' => _x('New Tour', 'post type singular name'),
		'add_new' => _x('Add New', 'tour'),
		'add_new_item' => __('Add New Tour'),
		'edit_item' => __('Edit Tour'),
		'new_item' => __('New Tour'),
		'view_item' => __('View Tour'),
		'search_items' => __('Search Tours'),
		'not_found' =>  __('Nothing found'),
		'not_found_in_trash' => __('Nothing found in Trash'),
		'parent_item_colon' => ''
	);

	$args = array(
		'labels' => $labels,
		'public' => true,
		'publicly_queryable' => true,
		'show_ui' => true,
		'query_var' => true,
		'menu_icon' => get_stylesheet_directory_uri() . '/images/divasicon.png',
		'rewrite' => true,
		'capability_type' => 'post',
		'hierarchical' => false,
		'menu_position' => null,
		'supports' => array('title', 'editor', 'thumbnail')
	  );

	register_post_type( 'tours' , $args );
}


add_action("admin_init", "admin_init");

function admin_init(){
  add_meta_box("tour_info", "Tour Information", "tour_info", "tours", "normal", "low");
}

function tour_info(){
  global $post;
  $custom = get_post_custom($post->ID);
  $tour_when = $custom["tour_when"][0];
  $tour_duration = $custom["tour_duration"][0];
  $tour_where = $custom["tour_where"][0];
  $tour_google = $custom["tour_google"][0];
  $tour_walking = $custom["tour_walking"][0];
  $tour_price = $custom["tour_price"][0];
  $tour_home = $custom["tour_home"][0];
  $tour_link = $custom["tour_link"][0];
  ?>
  <style type="text/css">
  .tour label{float:left; line-height:30px; width:200px;}
  .tour input{width:300px;}
  </style>
  <p class="tour"><label>When:</label>
  <input name="tour_when" value="<?php echo $tour_when; ?>" /></p>
  <p class="tour"><label>Duration:</label>
  <input name="tour_duration" value="<?php echo $tour_duration; ?>" /></p>
  <p class="tour"><label>Where:</label>
  <input name="tour_where" value="<?php echo $tour_where; ?>" /></p>
  <p class="tour"><label>Google Maps URL:</label>
  <input name="tour_google" value="<?php echo $tour_google; ?>" /></p>
  <p class="tour"><label>Walking Time:</label>
  <input name="tour_walking" value="<?php echo $tour_walking; ?>" /></p>
  <p class="tour"><label>Ticket Price:</label>
  <input name="tour_price" value="<?php echo $tour_price; ?>" /><br />
  Enter only the ticket price, leave off the $ sign.</p>
  <p class="tour"><label>Sidebar text:</label>
  <input name="tour_home" value="<?php echo $tour_home; ?>" /></p>
  <p class="tour"><label>Link URL to buy tickets:</label>
  <input name="tour_link" value="<?php echo $tour_link; ?>" /></p>



  <?php
}

add_action('save_post', 'save_tour_details');

function save_tour_details(){
  global $post;
   if (defined(‘DOING_AUTOSAVE’) && DOING_AUTOSAVE) {
return $post->ID;
} else {

  update_post_meta($post->ID, "tour_when", $_POST["tour_when"]);
  update_post_meta($post->ID, "tour_duration", $_POST["tour_duration"]);
  update_post_meta($post->ID, "tour_where", $_POST["tour_where"]);
  update_post_meta($post->ID, "tour_google", $_POST["tour_google"]);
  update_post_meta($post->ID, "tour_walking", $_POST["tour_walking"]);
  update_post_meta($post->ID, "tour_price", $_POST["tour_price"]);
  update_post_meta($post->ID, "tour_home", $_POST["tour_home"]);
  update_post_meta($post->ID, "tour_link", $_POST["tour_link"]);
}
}
function save_tours_details(){
   global $post;
   if (defined(‘DOING_AUTOSAVE’) && DOING_AUTOSAVE) {
return $post->ID;
} else {
    update_post_meta($post->ID, "tour_when", $_POST["tour_when"]);
  update_post_meta($post->ID, "tour_duration", $_POST["tour_duration"]);
  update_post_meta($post->ID, "tour_where", $_POST["tour_where"]);
  update_post_meta($post->ID, "tour_google", $_POST["tour_google"]);
  update_post_meta($post->ID, "tour_walking", $_POST["tour_walking"]);
  update_post_meta($post->ID, "tour_price", $_POST["tour_price"]);
  update_post_meta($post->ID, "tour_home", $_POST["tour_home"]);
  update_post_meta($post->ID, "tour_link", $_POST["tour_link"]);
}
}

function save_tours(){
   global $post;
   if(!isset($_POST["tour_when"])):
      return $post;
   endif;
   update_post_meta($post->ID, "tour_when", $_POST["tour_when"]);
}