I have an early 1980's 15 hp short shaft that is being a pain. I rebuilt the carb, did a complete ultrasonic on it and put it all back together with new parts. My question is it will not start, even choked, unless I give a little fuel into carb. Once I have it started it will run awesome and fire right up if I stop it. If I let it get cold it wont start again. Could a bad fuel pump be the cause of a no start when cold, like its not pumping enough until running? The primer pumps up solid? TIA Jason