This might not be much help, but if 'some fuel comes out', as in, it is actually .leaking. fuel, then you need to get that taken care of before anything else... you should also just put in a brand new fuel line, they are cheap as dirt.
If it just dies at over 50% throttle, as far as I know it could be a lot of things, but most likely are timing (if it is off just the right ammount it might work at lower rpm's) and dirty carb.
Clean the carb first and try some 93 octane gas, because as I read before, it combusts at a higher temp, and will help to keep the piston from compusting the gas rather than the spark plug, IF that is the problem.
So... clean the carb, good gas premix (PRE MIX IT!), check the fuel valve, new fuel line, in-line filter, and if all that doesnt help, check the timing and clean the points.
Most of that is general maint. stuff anyway, no reason not to do it, especially the fuel stuff if you are having problems.