Regular client initiated requests to the node server are captured fine in Fiddler. However, requests sent from node to a web service are not captured. It did not help to pass in
Fiddler works by setting your "Internet Options" (from start menu) "Connections" > "LAN Settings" > "Proxy Server" to its port, thus making all HTTP traffic (clients which obey this setting) go through it.
You should point your node.js client lib to use a proxy, the settings are written in that options dialog after you start Fiddler.