Always ran excellent, now runs for 30-45 secs before acting like starving for fuel, then dies. Changed out plug that was medium brown, cleaned fuel tank and removed tank filter. New fuel (old was new too) and checked all fuel lines for flaps and kinks. Took Walbro carb apart and cleaned thoroughly and checked diaphragms...........nothing changed. Changed carb with my backup motor, no change. It runs absolutely awesome, then starves out. The only thing I see is the priming bulb is now cracked and leaks, I even bypassed the bulb after priming the motor.......no change.............
Bob

First thing to do is change the primer... that is most likely to problem as bypassing it in most cases is not a good thing. The other thing might be a plugged fuel filter in the tank.

Oh ya... check the screen in the muffler, it could be slightly plugged. Normally you can just grab it with a pair of plyers and pull it out but you might need to loosen the one screw that holds on the cover over the screen.