Evinrude 140 V4 looper high idle

[Silvafox]

So I'm pretty new to outboards, only had a couple in the past and never had to mess with them so not 100% what I'm doing, that said I'm reasonably familiar with engines in general and have a marine background (worked for Scott waterjet in nz for a number of years designing building and fitting out boats along with assembling jet)
The problem I'm having is with an early 90s 140ho V4 looper, no matter what I do I can't seem to bring the idle down, but the issue seems to being caused by 1 cylinder alone, pulled all the leads 1 by 1 and only 1 dramatically reduces revs, and running this cylinder alone revs extremely highly when compared to the other 3. Have cleaned the carbs and swapped to eliminate them as the issues, tried to find a leak with wd40 and brake clean but to no avail.

Any suggestions on what to look for next?? I'm stumped.

 

[oldboat1]

think the next step is to look for a manual that is specific to your motor. Locate and post a model number for your motor, usually on the mounting bracket.

 

[emoney]

Agreed with the Factory Service Manual. You can purchase a "download" version for a lot less and have it almost immediately. It's like $20.00. That motor, I think, has the OIS ignition system. If nothing else, google that, and there's some pretty clear info on the web on how to troubleshoot/diagnose issues. I think I remember that the SM says Idle adjustment is done with timing, but don't trust me on that because I would really need to see the manual to know.

 

[Silvafox]

Have checked how to set the idle, and the idle is fine for 3 cylinders, as soon as trouble cylinder lead is attached it picks up to around 2500, and if runs JUST on that cylinder its still over 2000...making me think leak rather than timing.

 

[Silvafox]

But thanks I'll look for a manual tomorrow.