Return line over pressurizing tank, causing return line to leak at carb.

[sdamer59]

I had a 2-cycle leaf blower that had sat for 5 years. I removed carb, cleaned, reassembled and adjusted carb the blower now runs great. However, I have a problem with fuel leaking at the return line connection at the carb because tank does not vent and back pressure builds and causes the leak. If I try to blow into the return line going back into the tank it is completely blocked, no venting. When I throttle up to full throttle the return line bubbles in the tank with quite a bit of force. If I loosen the fuel tank cap the leaking at the carb/return line stops, however fuel then spills out the fuel tank cap.

Trying to understand if I have a carb problem or a tank venting problem. Should the fuel tank of a 2-cycle engine be able to vent off pressure caused by fuel being returned back to the tank? Or, should I not have more fuel returning than what is consumed by the carb?

As I stated before, the engine is running really well. I've adjusted the High & Low side set screws by closing all the way, then backing both out 1 full turn, each was adjusted no more than 1/2 turn from there to get the engine running really well. This issue with the back pressure building in the tank and leaking at the carb/return line is my only issue.

Anyone have any insights on what my issue may be? (It's a Homelite Vac Attack II leaf blower.)

Thanks for any help.

Sandy