Chainsaw Repair

On the check valve side of the carb no matter if it's an Hu Tillotson or A (I think ) Walbro Wt carb there is a teeny weenie little screen .That thing is the last line of defense to stop stuff in the gasoline from entering the carb .

Fact the screen is so fine it will catch stuff that can pass through the fuel filter .If it gets clogged no amount of tugging on the string will get it started .It can be such a thing as it becoming clogged but appears clear . You about have to pluck it out with a needle and look at it .

It can be blown out with compressed air but hang onto it with a pair of needle nose pliers because if it gets away you'll never find it again .

I'm not saying that's it but I've been down that road before .Fact  blown a screen into orbit myself a time or two ,then dig through my junk until I find another .