I have been lurking on this site for a month and found a lot of helpful information. Here are some things I found that helped me with a Walbro carburetor on my neighbor's little Poulan. I borrowed it knowing it had sat for more than a year. It ran about 3 minutes and sputtered out. So I went through the carburetor and fuel system. When I got it running again, I just gave it back. I bet in a year he will try to use it and I will be ready to repeat the procedure. 
Walbro Service Manual:
http://www.wind-drifter.com/technical/WalbroServiceManual.pdf
The manual covers all Walbro diaphragm pump carbs, so it helps to have the specific diagram for your carburetor. These can be found at
http://www.walbro.com/
Then go to Service & Aftermarket, then Aftermarket Parts & Service, then select your OEM and model or enter the carburetor under part number, as in wt-309.
Walbro Service Manual:
http://www.wind-drifter.com/technical/WalbroServiceManual.pdf
The manual covers all Walbro diaphragm pump carbs, so it helps to have the specific diagram for your carburetor. These can be found at
http://www.walbro.com/
Then go to Service & Aftermarket, then Aftermarket Parts & Service, then select your OEM and model or enter the carburetor under part number, as in wt-309.
