If you have already checked and refurbished (if necessary) the carburettor assembly, you should also check the fuel feed and the various lines, unions and filters that feed the carb; replacing degraded, cracked or corroding parts with new components where required.
Clean, correctly filtered fuel, is perhaps the most vital element for reliability - how many marine engines have failed (usually at the worst possible moment) through contaminated fuel? We would suggest a great many!
More fuel feed related components you may wish to consider:
Add as many items as you wish to the same shopping cart, new gaskets and screws (to replace those that are corroded beyond use) for example, and still only pay the same single fixed price shipping cost.
Please be aware that this component may have other applications within the Yamaha model range. So ensure the part-numbers you order are correct for your model.