'79 Evinrude 115 won't idle

[sailingMel]

My '79 Evinrude 115 won't idle. I have very carefully rebuilt the carbs, decarbed with seafoam, and got new Champoin plugs. It still won't idle right. When I start it on high speed it runs like crazy, but after running it at high rpm to warm it up, it will idle but spits or coughs about every 3-4 seconds. It also is not a steady idle but goes up and spits then back lower and back up and spits again over and over till it spits and quits.
Could this be timing issue? I have a manual but it's not real clear to me how to check the timing. What is #1 cylinder? do you use a timing light?
Any help and input will be greatly appreciated...
Mel
1969 17'Boston Whaler with Evinrude 115
1983 Hunter 34 Sailboat...Yanmar 3GMF

 

[oldcatamount]

Re: '79 Evinrude 115 won't idle

Sounds more like a carb issue to me than a timing issue. That "spitting" you mention is probably a lean sneeze. Be sure you have set the needle valves correctly and consider giving the low speed needle a little extra. Take a look at the "Top Secret File" at the top of this page for instructions for setting the timing.

 

[sailingMel]

Re: '79 Evinrude 115 won't idle

Thanks for the responce. These carbs don't have needle valves...just have slow speed and hi speed jets. I know these carbs are clean as can be, and all new parts inside. I"m still lost.
Mel

 

[emdsapmgr]

Re: '79 Evinrude 115 won't idle

I'd agree with oldcat. Sneezing at idle occurs when the engine runs lean. When idling, the carb butterflys are (should be) completely closed. At idle the fuel passes through special (very small) idle passages and idle jets. If you have any dried fuel or debris in these passages/jets, you can get that lean sneeze. You don't need a timing light to set the idle, even though the idle timing sets the idle rpm. The idle is set when the engine is in gear and the boat is floating at normal level in the lake. 650-750 rpm. Just adjust the idle screw on the timing advance lever and watch the engine tach.