Chainsaw has spark and fuel but still won't fire

Jerry, First thing to get is a new plug gaped correctly and try. Could need carb. adjustment, fuel filter replaced, bad fuel line(cracked/pinched), Dirt/faulty diaphragm in carb. plugged spark arrester in muffler,etc.
Check the attached links,instruction and guides, Good luck
"I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info."
https://answers.yahoo.com/question/index?qid=20090528073906AA0y882
Chainsaw will only run with choke
Stihl Chainsaw starts but won run
http://tekindoor.com/miscellaneous/stihl-chainsaw-troubleshooting

James, is there spark, fuel and is the choke staying on properly.
If it is trying to fire it could be a weak plug, stale fuel, dirty carburetor, or clogged exhaust screen in muffler, worn out low compression.
No spark with new plug, faulty switch, faulty coil. faulty plug wire, dirty weak magnets on flywheel.
Check the attached links,instruction and guides, Good luck
"I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info."

chainsaw troubleshooting woodland forum at permies

Chainsaw Won Start

You need to clean out the carb. possibly replace the Needle Valve and check the Diaphram for stiffness. Also check the fuel line for cracks and rott.

crank seals are probably shot :-(

remove the muffler and try it there is a screen inside the muffler that get carbon build up if it runs with out the muffler pry it open and clean it

try priming it mite work lol

If you have a good spark, and there is fuel at the plug, the only things to stop it fireing up are a sheared flywheel key knocking the timeing out, or the engine has low compression due to wear or damaged piston and ring.

If there is a good spark, and it occurs in the correct place ( remove and check flywheel key ) and there is good fuel at the plug ( not excessive, this would indicate flooding, so clean and service carb ) then it should fire, if not you need to check the mechanical condition of the machine, remove the muffler and check the condition of the piston skirt through the open exhaust port, any signs of scuffing and it will need to come apart.

hi there mwb15
have you made sure the ignition coil is producing enough voltage to fire under compression load ?

you may get a spark at the plug unloaded but under load it may be breaking down / weak making you think its got a fuel problem ?

does your system use a cdi coil system or point/condenser system ?
spark usually falls into weak spark, no spark catergory

if compression , fuel ( you replaced carb) and exhaust are ok , and you have air and vaccuum tight c/cases only things left are timming and spark

remember F A C T S

F = Fuel A = Air & ( air tight c/cases ) C = Compression T = Timming S = Spark

compression should be about 130- 140 approx if in good running order

take a look and let me know

cheers pauly46