1997 175hp Mercury Sportjet won't idle

Hello, new guy here. I appreciate being able to use this site and contribute where I can but after searching I can't find any info to help with my idle problem.
I have a '97 175hp Sport Jet in a Bayliner "Jazz". The boat has been sitting for a couple years and now won't start without a small burst of starting fluid. I did find the great information regarding the enricher valve check so I will be troubleshooting that system and hopefully remedying that part of the problem soon.
The other problem is that when I do get it running, it won't idle down. I see a number of adjustments but I'm afraid to mess with anything without consulting with the "experts" here. It runs about 2800 rpm. It's hard to do anything with the boat on a trailer since this engine speed will damage the impeller.
Any thoughts?

Re: 1997 175hp Mercury Sportjet won't idle

How long since the carbs have been throughly cleaned?

Re: 1997 175hp Mercury Sportjet won't idle

The carbs have never been cleaned. Good thought and something I should definately do but I have a "gut" feeling that the problem is that linkage isn't returning fully. If, when the engine is running, I carefuilly force the throttle linkage in the idle direction the rpms drop. Also, there is a large linkage lever associated with the throttle linkage that is on the port side and goes up under the flywheel.
When I push this lever forward it will lower the rpm but I think I may just be changing the timing?? When I move the linkage that is attached to all three carbs (engine off) it moves freely and apearently normally except I feel that it isn't returning fully. Part of the problem is the way the powerhead is installed the the "Jazz". The "hood" is hinged at the rear and only opens 45 degrees making it dark and difficult for a large person like myself to get close to the action.
I just had another thought regarding your comments about cleaning the carbs. If only one of the 3 carbs was messed up could that cause the engine to "race"?

Re: 1997 175hp Mercury Sportjet won't idle

If one carb were flooding, barely, that could raise idle speed, but usually a flooding carb will kill that cyl.

The fact that you can force the engine to reduce speed by pushing on the throttle linkage tends to direct me to a worn and sticking throttle cable.

Test with the engine OFF, disconnect the throttle cable and see if you can move the linkage back to an idle position. If so then it may be time to replace the throttle cable.

At idle the carb linkage roller is not in contact with the rest of the throttle/timing linkage, you should be able to turn the roller freely with your fingers. As the control moves, ignition timing advances, raising the engine RPM til the throttle roller contacts the cam at the mark on the cam, thats where the carbs begin to open along with more timing advance.

A worn throttle cable cuts a groove in the inner lining of the cable housing and often will not 'push' the throttle all the way closed.

You may be able to readjust the throttle cable to get an idle, however, the more the cable housing wears the more likely it will get worse, increasing the possibility of a stuck throttle. Not a wise idea.