Stihl 028 AV Super, stumbles at WOT.

[tlmartin84]

Looking for where to start diagnosing....


Saw has had a lot of new parts in the past 10 years, carb, fuel filter and hose, vent hose, air filter, clutch etc.


Saw is stuborn to start after sitting for awhile, Ive found pumping the gas to pull it up prior to starting it helps.



Anyhow, used the saw about 6 months ago with no issues. Picked it up this evening to go work a tree, ran fine for about 10 minutes, blocked about 6 cuts in a 24" tree.



It started to bog almost as if the chain binding. Pulled it up, let it recover and it bogged again.



It idles fine, will pull to wide open throttle, will stay there for about 5 seconds and then bogs and stumbles.



Clean filter, sharp chain, good gas, the vent and pickup hoses are all good.

 

[Brushwacker]

Make sure your spark plug is gapped 20 thousandths and there is no evidence of running hot or grey on the electrode. At some point you will do good to remove the muffler and check the condition of the piston. Check compression.(Some easy and I expensive things I would start with) ,drain all the fuel into a clear container, check condition of fuel and gas line.Correct anything u find wrong . Put in fresh new fuel recently from the pump.Start and take it for a test drive.