Parts list is here - I think this is your saw?
http://www.mccullochpower.com/ddoc/MCCI/MCCI2012_AAaa/MCCI2012_AAaa__576879301.pdf
If this doesn't help, pop over to my forum and post a couple of pictures and I'll try and ID the pipes for you.
Most of these small carbs have an internal fuel filter so it could be that blocked and / or the pick up filter in the tank. Adding fuel directly will bypass the entire carb system, not just the fuel lines.
Admin - www.gardenmachinerypro.co.uk, May 2012
