Wordpress 2.6 Problem With Showing Full Text RSS Feed Using Feedburner (Solved)
Self-hosted Wordpress 2.6 RSS feed only show the summary of the post even when setting is set to “Full text” mode for my Feedburner Feed.
If your RSS feed from Feedburner only display the excepts of your posts even after you have set your wordpress settings to “Full text” mode, just follow these steps:
Step #1
Go to Wordpress “Settings” -> “Reading” ->
Select “Full text” and then save changes.
Step #2
Go to Feedburner -> your feed dashboard-> “Edit Feed Details” ->
Change the Original Feed to -> yourdomain.com/?feed=rss2
Now go back to check your Feed, it should be working now. 
Summary
The likely reason for the problem that you face would have been because you have used the wrong feed source from your website. Feedburner requires “feed=rss2″ for full text and the default setting on your WP could have been “feed=rss”.