adjusting the idle

[brister]

I have a 1987 70 hp Yamaha and was wondering how to adjust the idle, it does not want to stay running when started.

[200090tlry]

If it's not wanting to run I would suspect

You have fuel leak and or dirty carbs. A sticking needle valve can say hey no more fuel is needed in this carb. Another area is fuel diaphram can go bad on mercury's not sure with yamahas there is rebuild $20. As a last resort you can try idle adjustment. On my 90 on center cyl little screw on top connecting arms I actual reduced my idle running little fast. To fast when going fwd to reverse wears out dog clutch in lower unit. Good luck I would start with carbs. Another quick fix might be running sea foam in tank maybe mercury quick cleen as well.

[Sparkieboat]

I agree..if it suddenly stopped idling, I would thing something is wrong. first thing I would do is get a new set of correct plugs, gapped right. then change water separator filter, and any other fuel filters..then stat checking fuel/carb issues, may be idle jet in one of the carbs is clogged..then spark issues. maybe old/watery gas??

[juanfishon]

You can also check if all timing linkages are tight on adjustment screws,check if lock nuts are tight.If thay are loose it can also bring your idleing down.