Sputtering/stalling B&S 5.0HP on Billy Goat leaf blower

Hello all,
A friend of mine gave me an old Billy Goat leaf blower that didn't run. I rebuilt the carburetor (as much as I could, B&S made it seemingly impossible to remove the old jet), replaced the fuel tank which was rusted out, and popped in a new spark plug. She probably hadn't been run in almost 10 years, but today she came to life! :thumbsup: Everything runs fine, but I can't let the choke out any more than about 1/3 of the way. I feel like it should have more power in it than what I'm getting, but when I let the choke out further it sputters and wants to stall. When I turn it off it backfires, but I'm thinking that could be because the mixture is too rich? I've tried adjusting the mixture screw but it hasn't helped with the stalling and sputtering issue. New fuel tank, new fuel, new gaskets, rebuilt/cleaned carb. Any suggestions as to what might be the cause?

Mixture is too lean.
Either a blockage in the fuel system, too low float cut off or air leak between the emulsion tube & the engine .

bertsmobile1 said:

Mixture is too lean.
Either a blockage in the fuel system, too low float cut off or air leak between the emulsion tube & the engine .

Click to expand...

I'm going to look into those today, thanks for the input. I know just slightly above nothing when it comes to these things, but I believe the float on this is fixed. I'm going to mess with the mixture a bit more, rich the crap out of it and see if anything changes. If not I guess I'll have to pull the carb back off and re-inspect the jet and check the rubber elbow on the fuel line to make sure there is no dry-rotting or holes otherwise.

You check for air leaks by starting the engine then spraying all around the carb and the tube that connects the carb to the engine with something like WD 40 in a trigger pack, not a spray can because the propellant can burst into flames.
If there are any air leaks the WD 40 will be sucked into the engine cazusing it to mis a bit and blow lots of white smoke which is very obvious.

To have an adjustable main jet it will have to be a very old engine
Most less than 30 years old only have an adjustable idle circuit and most of them became fixed about 10 years ago.

It will help greatly if you post your engine number and if you cant find it the a photo of the carb.

As for the backfiring.
Modern fuels burn a lot hotter than old fuels used to so the muffler gets well & truly hot enough to ignite an air fuel mix.
When you shut down the engine, you kill off the spark but the engine continues to spin and suck in fuel from the carb which it blows strait out into the muffler,,,, bang.