search

If you are looking to exlude feedapi nodes or webform nodes or maybe even node-types you ve created yourself using cck from your search results because they are not relevant.

Use http://drupal.org/project/search_block

Install and go to the settings page(settings > search > tab)
You ll be able to restrict nodes on a content type base from your search.

If your site was allready indexed you should re-index it. Go to settings > search to do it. Run your cron until everything is indexed.

Are you using a content type with revisions enabled?
This is incompatible with faceted search which builds it's query on the nid and not on the vid. For example if you edit a node with nid 10 and vid 20 and a term tid 1. A new entry in the term_node table is inserted: nid 10 vid 21 tid 2. The faceted search module will build a query using the nid and tid only. When you filter in your search for the term with tid 1 the module will query on tid 1 and will still find the node with nid 10 but it's the wrong revision of that node.