Chainsaw Repair

I have a k760 cut off saw. I couldn't get it to prime. I cleaned the carb and still couldn't get it to prime.. Bought a new carb. Still doing the same thing. If I take the carb out and put the priming bulb right on the line coming from the gas tank it primes right up.. what could be wrong. So confused..

My "redneck" method is to mix PU thinner and dishwasher liquid and immerse an inlet connection of the carb into it. If the primer sits on to of the carb. Use fingers to close the air inlet and outlet sides of the carb and then pump the primer. And pray . In 90% of cases whatever is causing stuck checkvalves will be dislodged and the primer will start pumping the redneck cocktail. Then try it with the air inlet and outlet open. If it stops pumping the jet valve is leaking. Pour some of the cocktail into the air passage, or even better, immerse the carb in the cocktail and keep pumping. Keep checking whether it can work out of the cocktail. When it does, move it into some fuel and pump, if it works, pump in some fresh fuel to flush it and try it on the saw.