1986 9.9 Johnson, need help setting the idle

[jrs_diesel]

I have a 1986 9.9 that I just got running again (I just bought the engine this past winter, good deal). The carb has the metal float bowl that had water in it so it had rusted up and clogged nearly everything. A carb kit, a thorough cleaning, new fuel lines, and she's running fairly well.

The issue that I'm having is that when I turn the throttle all the way to idle position, the engine dies. I can get the motor to idle if I set the throttle higher, and it idles like any motor would. How can I set it so that when I twist the throttle all the way to idle, that the engine will actually idle there? Seems like something is a little off, and I can't put my finger on it.

This motor is a little unique in that it was the first year that OMC installed the cable throttle in the tiller handle instead of the old gear/shaft setup.

 

[Daviet]

Re: 1986 9.9 Johnson, need help setting the idle

Low speed needle set to optimum RPM? What idle RPM are you trying to set it at?

 

[Monte1961]

Re: 1986 9.9 Johnson, need help setting the idle

I have a 1986 9.9 that I just got running again (I just bought the engine this past winter, good deal). The carb has the metal float bowl that had water in it so it had rusted up and clogged nearly everything. A carb kit, a thorough cleaning, new fuel lines, and she's running fairly well.

The issue that I'm having is that when I turn the throttle all the way to idle position, the engine dies. I can get the motor to idle if I set the throttle higher, and it idles like any motor would. How can I set it so that when I twist the throttle all the way to idle, that the engine will actually idle there? Seems like something is a little off, and I can't put my finger on it.

This motor is a little unique in that it was the first year that OMC installed the cable throttle in the tiller handle instead of the old gear/shaft setup.

You are going to elaborate a little more.

 

[Rick.]

Re: 1986 9.9 Johnson, need help setting the idle

http://www.sschapterpsa.com/ramblings/Ramblings.html
This link is a must read for anyone who owns a 9.9 or 15. So much good information and well laid out with picture to boot. We all owe Leeroy a debt of gratitude for his work. You may need to do a link and sync to get your idle working right. I have not encountered the cable throttle ( my small engines are 1982 and older) as of yet so can't say very much about it other than an untested belief that it must be far superior to the loosey goosey gear system it replaced. Best of luck. Rick.

 

[jrs_diesel]

Re: 1986 9.9 Johnson, need help setting the idle

That's gentleman's website has been an invaluable resource for me. He even has an article on the engine that I am rebuilding, a Johnson 72 6 HP.

I just looked at my 9.9 again. For link and sync, it looks like the roller starts moving about 3/16ths of an inch past the mark on the cam. I adjusted that to where it belongs. My low speed mixture is very close to being set correctly (need to run it again to get it just right). Hopefully the link and sync is all I need to mess with.

Here's a video I took that shows what I am talking about earlier. At about 10 seconds into the video you can hear it about to die before I twisted the throttle up a little. A little smoky but it's also burning off excess built up oil in the exhaust. And yes, I'm aware that it has the wrong hood

 

[AlTn]

Re: 1986 9.9 Johnson, need help setting the idle

was this engine warm and off choke when you made the video?...if your throttle plate is just beginning to open as the carb roller hits that mark on the timing cam, then, at wot the throttle plate is exactly horizontal and the roller is at the highest point on the timing cam, that's as good as it gets as far as link n sync go. It may help to decarb the engine, then set the idle mixture on the water with the engine warm and the motor in gear. That setting ring I see as a sorta guide. The start position we use is the gear selector in neutral, choke fully on, and throttle as far advanced as the neutral lockout will allow. When it fires, just reduce the throttle and let it warm up some.

 

[jrs_diesel]

Re: 1986 9.9 Johnson, need help setting the idle

Yes the motor was warm and off choke, it had been running about 15 minutes prior to me taking the video. The roller started moving nearly ?" past the mark on the cam. I have adjusted the roller linkage so that it starts opening when the mark hits it. And yes, the throttle plate is horizontal at WOT.

So, my idle probem is probably because the link and sync was out of adjustment?

My next step is to water test, set mixture and decarb. I have a new set of plugs for after the decarb too.

 

[AlTn]

Re: 1986 9.9 Johnson, need help setting the idle

doubt your link&sync was the problem as, in effect, you had the timing slightly advanced at idle...idle mixture adjustment was more likely culprit..decarb treatment should make a noticeable difference

 

[jrs_diesel]

Re: 1986 9.9 Johnson, need help setting the idle

It was the idle mixture. I was able to run it on the water today. I decarbed it, changed the plugs, and ran her good. Got the idle mixture set too and now it idles like it should.

Thank you all very much for the help.

Here's a video from on the water. Sorry it does not look that great, I used my camera phone. I don't know the speed either as I forgot to bring my GPS. :facepalm: