If it only runs on prime then it is starving for gas. take the gas hose off at the carburetor make sure gas comes out in a flow. if good flow. take off fuel bowl if you see any debris or water then you need to take off the carburetor and clean it really good with cleaner and put in a new needle and seat. make sure float moves easily. if you clean and install a carburetor kit it should run as it did new.