3.5 HP. Started with Black smoke and slow or rough idle for a few months but just keep using it. Finally more black smoke then would not start. Some things I did. Replaced head gasket. Checked spark. New fuel non ethanol. New oil made for small engines. Cleaned magneto etc. Finally decided to tackle carburetor. Yea should have started there maybe. Took all screws out but would not disconnect from intake or lift up from gas tank so I sprayed cleaner in many places and put back together. It won’t start. It seems like no gas so put some down air intake and it started and ran great then died like out of fuel. Put more fuel in air again and after a few pulls ran again for 15 seconds then stopped. I’m guessing I have a fuel problem. Anyones thought on the best way to tackle this issue. Did I not go far enough pulling the carburetor off and checking the fuel pick ups into the gas tank? Thanks for any advice.