Chainsaw Repair

 
  Well I ended up with a challenge, my neighbor came over with what I think is about a 3 year old saw. Its a 450 and has always run good. But this summer he ended up with the saw not starting after he would refuel it. I read about the possible fuel tank ending up pressurized so I checked for that. I read in the Manuel about a check valve under the recoil cover. I am not sure how that works . It looked like a steel dowel with a score mark about 1/4" long in the middle. Pulled it out and put it back in. Fuel filter is good, and a new spark plug. Have any of you experienced this ?  I have older saws and they have slots in the carb screws so I didn't try any carb adjustments. I did try adding a small amount of fuel into the carb but it made no difference.  I also checked for spark and it was there. If the saw sits for a few hours and cools back to the ambient temp it will start.
 Please share your thought's.

Thank You for any help you can give me.
Wade

+1 Adam, the saw is probably flooding.

you could also try and leave the fuel cap a little lose when you refuel it when it is hot and see if it restarts. If it does start I would look towards the tank vent as the problem. As mentioned above check for spark when it is hot.

Wade
Looks like there is the slotted rod you looked at as well as a small plastic " vent"  pressed into the same hole.  Not real familiar with this set up. My guess is the vent filters crap from entering the grooved  rod that vents the tank?

Study the plastic where the rod is inserted, could be that the rod is pressed in and the plastic compromises the slot, not allowing it to vent.  If the vent turns put to be ok,  Pull the carb apart and install a carb kit in it.  If the metering needle is not sealing properly because it has been compromised by bad gas or if the fulcrum arm fork is bent it will allow the needle to leak and flood the saw.