I have a website http://www.freearticlesdb.com but Google is not indexing them properly. I see most of them are .pdf files. I have got around 7000 articles but only few of them got indexed. I do not have any errors in the webmaster tools. sitemap and robots are getting downloaded everyday. Your help is much appreciated..!
Try to creating a sitemap for your site and submit it to Google and other 2 big search engines. I think this would help in deep, thorough indexing purpose. Have a nice day,
How old are the pages of your website? It can take some time for new pages to be visible in the Google index.