chainsaw carb problems

[dlovett]

I got a poulan 2000 chainsaw for free. Compression seems ok. I'm wanting to revive it for personal use, but am banging my head w/ the carb. It has a walbro wt-20. I've replaced the fuel lines and filter, etc. It still will not start. It will run for a couple of seconds if I dump gas into the cylinder. I've disassembled the carb (including pulling the welch plugs), soaked it in carb cleaner for three days, put in new gasktets, new needle & lever. I've disassebled it a few more times to make sure every orifice and passage is clean and I really think they are clean. This is the first walbro w/ welch plugs I've rebuilt and am not really very familiar with those. I did put them back in and flattened them down with punches. I have not sealed them with fingernail polish yet. Can not sealing the welch plugs actually cause it to not even start at all? I was wanting to make sure it would at least try to run before I painted the welch plugs. Anyway, do any of you have any suggestions or something I may have missed? I'd rather not buy a new carb because it's not worth it on this old junker; unless someone knows a source to get them cheap. (wt-20 interchanges with wt-309)
thanks.

[ducky1]

after you get the saw to run by dumping gas down the carb, does the carb have gas inside where the diaphragms are? If you tear down the carb and it has gas in the diaphragm part and still wont run, I would look at the crankshaft seals. They have to be good to have enough vacuum to get fuel air mix into the Cly. If the carb is dry inside, it is not getting gas past the inlet needle. Needle adjustment is important on those carbs also.

[dlovett]

Thanks Ducky1. Yes, it does get fuel into the carb. I will check out the crankshaft seals. Thanks for the insight.

[dlovett]

Another question: If I put my thumb over the air/fuel intake, and pull the rope should I feel a vacuum? Should I be able to see the reed valve open? I will disassemble as soon as I have a chance. Thanks.

[dlovett]

update: It works now. Ducky1, you got me on the right track. It was vacuum-related. The cylinder gasket was the culprit. Works like a new cheap chainsaw now!