Mercury 115 2 stroke 2+2 high idling rpm

**killerpirate** · 03-27-2020, 03:39 PM

My Merc 115 2 stroke 2+2 is idling very high, around 1700-1800 rpm, so shifting is a little tough on the gears. When i shift in gear rpm drops to 800 +- It runs like a dream, except when i want to do a hole shot, it needs some time to response to the throttle. Couple of seconds sometimes. But then rpm comes up and after that flies like a missile. Its only when i do a holeshot. If i build it up, or when i hit the throttle when im already on plane it works fine. Oh and also sometimes te engine holds back a little bit when on full throttle. Not much, but you can definitly feel it backing down. I guess those problems are unrelated.

What could the issue be? I changed the plugs, changed fuel lines, cables, cleaned filters, checked sparks / bobines. I did not yet pull the plugs of the bottom 2 cylinders te see what happens on idle. I guess they are running along on idle. Also the levers are returning in there original positions when pulling back the throttle.
when i pull the trigger arm forward (to the bow) rpm drops.
Could it be that my acceleration pump is faulty? (It sticking open i dont know) or perhaps some bad reeds? I am facing a mystery here, any help is welcome!

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**killerpirate** · 03-28-2020, 06:31 PM

Any suggestions are welcome

**FORBESAUTO** · 03-28-2020, 07:56 PM

Many many possibilities. 1st thing I personally would start with looking for would be a vacuum leak from crank seals, intake and such. And of coarse link and sync/all linkages moving freely (carbs closing all the way/idle timing coming down to where it’s supposed to be.

**Capt.Insane-o** · 03-29-2020, 11:02 AM

Pull the accelerator pump apart and look at the diaphragm. They are starting to get stiff with age, also make sure all the check valves are clean and working. The bleed and enrichment circuits are those motors are fussy.