1975 9.9 johnson . This motor looks really nice for its age it has 100+ on both cylinders and pretty good spark. Any the carb was a mess I cleaned it up really well blew out all the ports real good cleaning. Anyhow the problem is when I pump the bulb from the tank I can't even get half a pump and it hard as a rock. I took the gas line off at the carb and it pumps fuel clean through but the second you put it on the carb it stiff again ???? Any ideas