1990 Mercury 115 2+2 wont idle.

[Joey Rodgers]

I have a mercury 115 that I cant seem to get to idle. When I first picked up this outboard and the 1990 astro craft it is on the back of it wouldn't start. It hasn't idled from the get go. I've rebuilt the fuel pump, changed out fuel lines, cleaned carbs, ran compression checks, changed the starter, installed a water seperating fuel filter, and changed minor fuel filters. The only way to keep it running is to click in the key to open the enrichment valve. Ive reset idle mix screws to mercury maintenance manual specs at 1 1/4 turns out. I havent touch the screws on the throttle arm because I'm not sure which screw is which. Anyone have any ideas on what I should try?

 

[racerone]

Having to use the enrichment system clearly points to a carburetor problem.---------That motor only runs on the top 2 cylinders when idling.----The bottom 2 carburetors kick in once engine speed exceeds about 1800 RPM.---------Revisit top idle mixture adjustment.---------Post your compression values if you like.----------Something was overlooked in the carburetor work.

 

[Docksidemarineservices]

Here is an engine that has to be set up by the book and set up while the boat is floating. Get the procedure, read it and follow it from A-Z.

 

[Joey Rodgers]

Ok I found the procedure for idle speed and mixture in the mercury. Where is the idle speed screw located at the book references it alot but never points it out. Is it on the throttle arm? And if so which one is it?

 

[kaotic1]

Ok I found the procedure for idle speed and mixture in the mercury. Where is the idle speed screw located at the book references it alot but never points it out. Is it on the throttle arm? And if so which one is it?

If either one of the top two carbs is hung open those models wont idle well, try loosening the screws on the linkage connecting the carbs and snapping them all open and shut then retighten the screws, and make sure the wheel rolls free where it contacts the throttle lever it also has a screw to adjust the position of the wheel, and finally float it in water to adjust the idle miture screws on the port side of the carbs. I hope this helps some those were tricky models.