I don’t know if this will solve your issue, but I just came across a solution that worked for me. It seems that my theme did not link to the RSS 2 feed. Apparently, you can only get full feeds through browsers if you are using RSS 2 regardless of the Reader Setting. Hope this helps.
According to this post about this RSS feed issue, it seems that your problem may be that your theme may not be using bloginfo(’rss2_url’) as the URL behind your RSS link. You may want to check this out. You will not get full text feeds through a browser if you are not using RSS version 2 regardless of whether you have it selected in your reading settings or not. Hope this helps.
