I've had one kinda like this before, if it won't run and I'm not sure if fuel or ignition,
I spray a little brake clean in intake to see if will run, if it does not ignition problem(ether hangs around too long).
Wouldn't start but would run on brake clean, fuel supply was good, ended up taking off mixer(2 bolts) and found the little vacuum ports in mixer plugged with carbon, cleaned them out with mechanics wire, fired right up,
Just a thought...