When you select a suggested keyword the search should start automatically!!!

I agree this would be nice to see...

It could be that this simply isn't possible given Drupal's implementation of autocomplete. There is currently a discussion about enhancing autocomplete but I don't know that this has come up: #125231: Enhance autocomplete feature

Having said that we should be able to make it work with a little bit of JS trickery- api.drupal.org manages to do it with the following snippet:

Drupal.behaviors.apiAutoComplete = function (context) {
  $('#api-search-form:not(.apiAutoCompleteProcessed)', context).addClass('apiAutoCompleteProcessed').each(function () {
    // On the first focus.
    $('#edit-search', this).attr('autocomplete', 'off').one('focus', function () {
      var $this = $(this);
      // Prefetch list of objects for this branch.
      $.getJSON(Drupal.settings.apiAutoCompletePath, function (data) {
        // Attach to autocomplete.
        $this.autocomplete(data, {
          sort: function (a, b) {
            return a.value.length - b.value.length;
          },
          matchContains: true,
          max: 200,
          scroll: true,
          scrollHeight: 360,
          width: 300
        }).result(function () {
          $this.get(0).form.submit();
        }).focus();
      });
    });
  });
};

I am no JS guru however, so someone else might need to take the lead on this if you want it done soon.

I needed this functionality too, so to get it done quickly I borrowed some code from the finder_autocomplete module.

I have attached a patch for the drupal 6 version which seems to work for me so far.

Thank you very much, your patch worked great :) I now have this functionality working with Drupal 6.16.

Pretty simple fix I've been using. Just add this to your theme's script.js:

$(document).ready(function() {

  /**
   * Puts the currently highlighted suggestion into the autocomplete field
   */
  Drupal.jsAC.prototype.select = function (node) {
    this.input.value = node.autocompleteValue;
    this.input.form.submit();
  };

});

This overwrites the function from autocomplete.js ... pretty simple! Oh, and the only difference from the original is the addition of this.input.form.submit();

Hope this helps some poor (unfortunate) soul like myself.

Yes, jmonkfish's solution works for me too. Don't forget to empty your sites cache to make it work though... ;-)

oops...nevermind.

I ended up needing to do some jQuery selectors so that it didn't always submit, for instance on an add/edit node page. You could probably just check the name of the input before submitting the form.

if(this.input.name == 'searchBox'){
  this.input.form.submit();
}