How to disable "Store pick up" option for products over certain weight?

I use both store pickup and zone rates options. Zone shipping table is set by weight. Since products over 900Kg is not suitable for picking up by customer, I have to disable the store pick up option for these products at the check out but keep the delivery option. Can anybody please help?? Thank you in advance

You could customize the Store Pickup module with the code:

    $this->enabled = ((MODULE_SHIPPING_STOREPICKUP_STATUS == 'True') ? true : false);

// bof: turn off when weight of a product is >= 900
      if (!IS_ADMIN_FLAG) {
        global $cart;
        $products = $_SESSION['cart']->get_products();
//echo '<pre>'; echo var_dump($products); echo '</pre>' . '<br><br>';
        for ($i=0, $n=sizeof($products); $i<$n; $i++) {
//echo 'Products ID: ' . $products[$i]['id'] . ' name: ' . $products[$i]['name'] . ' weight: ' . $products[$i]['weight'] . '<br>';
          if ($products[$i]['weight'] >= 900) {
            $this->enabled = false;
            break;
          }
        }
      }
// eof: turn off when weight of a product is >= 900

    if ( ($this->enabled == true) && ((int)MODULE_SHIPPING_STOREPICKUP_ZONE > 0) ) {

This is assuming you just care about quantity 1 of a Product being >= 900 and not the weight of the cart or multiple quantities of a Product ...