Re: 1980 90HP mercury very High idle
If that's not it, check the "idle stop" adjustment, be sure you mess with that and not the maximum spark advance stop. You may need to readjust the throttle cable after re-setting idle speed.
If this is a distributor model, it's also possible that the drive belt is off by one tooth advanced which would make it idle too fast. In that case, you'd have to pull the cover off the distributor pulley and correct the discrepancy. You'd also have to check/readjust max spark advance if you did this.
Also check for leaking vacuum hoses which could potentially cause a fast-idle condition.
A "link-n-synch" is probably in order at any rate, that way you're not going to burn up the motor from too much spark advance.
Check out the posts on this forum regarding Care and Feeding of Inlines and you'll soon be doing your own work! Here's a good place to start:
http://forums.iboats.com/bbBoard.cg...matebb.cgi?ubb=get_topic;f=29;t=014508#000000
If you have problems with the link, the article is located in the FAQ section and is titled "Timing and Sync of Merc Inlines (to 1988)".
BTW unless you have a detailed maintenance history of this motor, it's a good idea to install a water pump repair kit (or at least renew the impeller). Very cheap insurance to prevent an expensive powerhead meltdown from failure of the cooling system.
This site sells replacement parts, and I've gotton lots of good deals and good service at
www.boatfix.com.
HTH............ed
I have an entire winter in the garage to fiddle with it