How to monitor web requests from localhost to localhost using Fiddler

You need to change the request url to use machine name or non-local IP address instead of localhost or 127.0.0.1 For example, instead of http://localhost:8081/mytestpage.aspx or http://127.0.0.1:8081/mytestpage.aspx, use http://machinename:8081/mytestpage.aspx or your IP address (e.g. http://10.2.40.xxx/xxxx)

See http://docs.telerik.com/fiddler/Configure-Fiddler/Tasks/MonitorLocalTraffic