Merc 3.0 Idling High when in Neutral, but fine in Gear

U

uofmskibum42

Recruit
Joined
Jul 23, 2007
Messages
1
I have a '89 3.0L Merc I/O that idles up around 2000 when it's in neutral, then after I shift into gear, it idles a bit lower, but not where it should be. I've tried fuel system cleaners, and carb cleaner, but it still persists. Any tips or suggestions?
 
tommays

tommays

Admiral
Joined
Jul 4, 2004
Messages
6,768
Re: Merc 3.0 Idling High when in Neutral, but fine in Gear

That must be soem BANG when you put it in gear :eek: and will destroy the drive if you keep doing it


When correctly tuned up you should be able to idle around the 650 to 700 rpm range


Tommays
 
Don S

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Merc 3.0 Idling High when in Neutral, but fine in Gear

Disconnect the throttle cable from the carb linkage and see if it idles down.
Then adjust the cable barrel to just preload the carb linkage to the idle position.
 
W

Wotam

Petty Officer 2nd Class
Joined
Jul 22, 2007
Messages
108
Re: Merc 3.0 Idling High when in Neutral, but fine in Gear

Does your engine have an idle adjustment (stop) screw? It is usually mounted on a plate where the throttle cable linkage attaches to the carb butterfly.

If you have one, you might try backing it off a bit and see what you get.
 
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