If your Poulan Pro chain saw doesn't respond to a few sharp tugs on the starter cord by breaking into a satisfying buzz, there's a problem with either the fuel, spark or air. Those are the three ingredients necessary for ignition, and when one is lacking, it's like trying to start a fire with wet wood and a broken lighter in a stuffy room. Before you troubleshoot, make sure you're following the correct starting procedure.
Correct Starting Procedure
You must set the choke to the "FULL" position when starting your Poulan chain saw cold; it should automatically lock the throttle in the starting position. The next important step -- which is surprisingly easy to overlook -- is to set the switch to the "ON" position. Depress the primer bulb four or five times to pull air out of the carburetor and fill it with fuel. Pull the cord with four or five short bursts, and when the engine turns over, immediately set the choke to the "HALF" position. If the saw doesn't start after five pulls, set the choke to the "HALF" position and pull four or five more times.
If you smell fuel after pulling the starting cord several times, the engine is probably flooded, which means there is too much fuel in the carburetor and not enough air to ignite it. The fuel will evaporate if you allow the saw to rest for 20 to 30 minutes, but if you're in a hurry, you may be able to start the saw by following a special procedure. Engage the fast idle by pulling the trigger and locking it, then set the saw on the ground and pull the starting rope sharply; it's important to avoid pulling the rope out to its full length. If the saw doesn't start after 15 pulls, it's time to troubleshoot.
Dirty Plug and/or Filters
The spark plug can get fouled when the engine floods, or it can simply be old and need replacing. Unscrew the plug with a spark plug wrench, wipe off the terminals and inspect them. If they are caked with oil, severely blackened or corroded, replace the plug. While you're performing this maintenance task, you should also remove the air filter and clean it with soapy water -- to access it, remove the cylinder cover from the top of the engine and pull off the air filter cover, which is just above the saw handle. Remove the spark arrestor and clean it; if it's dirty, it's preventing the air circulation necessary for ignition. It's located just behind the muffler. You should also pull the fuel filter out of the gas tank, check it and replace it if necessary.
Fuel Quality Issues
If you left your saw sitting in the tool shed for an extended period with gas in the tank, and no other troubleshooting procedures are effective, the fuel is probably fouled. This happens because moisture collects in gasoline during cold, rainy weather. It sinks to the bottom of the tank and gets sucked into the carburetor. To remedy this, remove the gas cap, turn the saw over and drain the fuel into an appropriate container, then refill the tank with the proper fuel/oil mix. Before you start the engine, spray a small amount of starting fluid through the air filter aperture to help ignite the new fuel. Once the engine is running, any remaining moisture should evaporate.