Amamba,

OK, the fuel pump works and gas is definitely being delivered to the
carb. The ignition system is delivering spark to the engine, also. Time to
get a rebuild kit and rebuild the carb. During the rebuild give every
orifice a good squirt of carb cleaner. Soaking the carb in gas overnight
also may help to clean the carb. After the rebuild you will need to adjust
the various needle valves. This is usually discussed in the instruction
sheet included in the rebuild kit.
If you're uncomfortable with adjusting the carb's needle valves or the
grass is getting really high take it into a shop but I think you'll find
that this is not hard so long as you work meticulously and in an area where
you don't lose dropped parts. Some of the screws are pretty small and there
is always a spring that wants to get lost.

Good luck,
Dave M.