My 2150 chainsaw was my favourite longest serving Poulan. It has the separate choke and kill switch which I prefer.  Now won't start and extremely hard to pull almost like timing too advanced.  Good spark, new spark plug, fresh gas, new gas filter, new fuel lines, new primer bulb, 40:1 mix.  Remove spark plug and turns over smoothly and easily.  Insert plug and leave plug wire off and it seems to pull easier, or my imagination. I'm not stuck for a saw, I have three more newer Poulans.  I just hate being stumped by a little two cycle motor.  It has the Walbrow carb.  I don't suspect the carb because injecting a small squirt of fuel still no fire. Any ideas out there?  Edit....also removed muffler to make sure it wasn't clogged...no difference.