I have a blog and its posts date back all the way to March of 2009. However, when I visit my feed url (it's feedburner), the oldest post that shows up on that page is one written in February of 2011. How do I view ALL posts on a blog with a feed url?
RSS feeds are usually just XML documents that are generated dynamically every time a reader requests them. They contain only as many recent posts as it is set by the tool you use. They do not contain all previous entries unless you specifically tell them to, should it be possible in the CMS you use. However, feed readers like Google Reader keep extensive archives of the feeds they have requested, so you may try to access the feed this way and check if Google Reader has archived it.