I have an older PB 400 blower that I keep around as a backup, but it's become so unreliable it's not even good for that. The main symptom is that it will crank, run very strong for a minute, then start to lose power, surge back a little, then eventually die out. It has a fairly new carb on it. Has been cleaned recently. Plenty of fuel in tank. Seems to get a good spark. Air cleaner is new. I suspect it's some sort of problem with the fuel delivery from the tank to the carb, but I don't know much about these engines. This unit doesn't seem to have a seperate fuel tank vent, or does it? Is a a vacum somehow preventing fuel from flowing? Any ideas? PS....anyone know a good book on 2 cycle troubleshooting that gives real-world tips. I'm sure some of this stuff is simple once you've seen it.