Merc 60 HP - Low RPMs once warmed up

Help......
The motor has been checked by certified mechanics twice and they have yet to repair the problem. Thus far, plugs have been cleaned, compression ratios tested, fuel drained, fuel filter replaced, etc...

Motor: 1989 Mercury 2 stk 60 HP (immaculate condition)

Problem:
- once engine heated (between 5 to 15 minutes), and the forward gear engaged, the RPMs drop from 57 to 22.
- however, the RPMs will go up to 65 when in neutral
- the RPMs will also go up when in reverse

I initially thought there was a problem with the throttle cable but the certified (?) mechanics either don't listen, don't know and/or it is NOT the problem.

Please help....
Little Bass Turd in Ottawa, Canada

Re: Merc 60 HP - Low RPMs once warmed up

First don't free rev a outboard, it proves nothing and can cause damage. The problem only accures with a warm motor. If it runs alright after it cools off, that would point to a winding, a coil or the stator with a coil you would have a seady miss as if a plug was fouled out. With the high speed winding on the stator the engine would seem to bepulling wit all cyls but would simply refuse to rev up. Usally on a 3 cyl if a trigger or switchbox fails you would lose 1 cyl and your engine is losing to many RPM for 1 cyl. If all else fails those 60s have a bad habit of the sleeves moving around when they get warm changing the port timing but they normal don't lose the RPM your losing. Hope this helps with ideas

Re: Merc 60 HP - Low RPMs once warmed up

Thank you Laddies. I will discuss your comments with some mechanics.