There is a small check valve thats under the bulb. Heavy pushers crack it and then it wont work. The style of carb is used on a lot of different models so check with a local shop to get the right part. It doesnt have to be a ryobi dealer it could be stihl or echo. The other thing you have to check is the lines. Often they get pin holes in them from the ethanol in our gas. Roll the lines between your thumb and fingers while looking for cracks or holes. Last bit of advice is the fuel outflow is coming from the top fuel port near the bulb so if the lines are on backwards you will know whats up. I would replace the fuel filter and both lines while you have it apart and that way you know its good to go for awhile.

Best wishes,
Bob

thanks bob for the response, I looked a the umbrella seal Didn't look bad, but when I tried to remove it for closer inspection it broke at the ball seat. I put new carb kit in and it fixed it. thanks again