Mad force problem

[oldo556]

Mad force with gx21 engine. Use about half of a full tank, then it shuts off. After that, if you feel like getting started, you can make your hand hurt. The engine doesn't start.
At first I thought the fuel would show that it doesn't get after half a tank, I changed the tank, renewed the hoses, but no effect.? There is a crack in the "rubber corner" of the exhaust pipe that faces the barrel, which the previous owner apparently tried to patch with tape and glue. Could it be that it's still leaking and thus no more pressure can be enjoyed in the tank, or where is the problem?

Sorry my bad english. (Google translate)

 

[dasrcparts]

Sounds like its getting warmed up and losing compression. May need to be re-pinched which means new piston and sleeve