Tag,

I think Jens has the solution. You probably have it so over-compressed that it is oscillating. Start it as you normally do and back off compression. If it kicks over in the wrong direction it will stop from lack of fuel (like running off a prime). If it kicks off in the correct direction it should continue running if the fuel setting is not too lean.
You might try backing off compression about 1/2 turn and use only an intake prime with fuel tank disconnected. When you can start it that way, then connect the tank. Solve one problem at a time.

Good luck,
George