79 Merc 40 hp Rich on low rpm sometimes falls on face at high rpm

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HillbillyDan35

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Aug 15, 2006
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Ive got a 79 merc 401.40 hp.It runs real rich at low rpm"s (when trolling).It fell on it"s face when I opened it up 2 days ago. I'm going to try seafoam first.But I don't know where the lean rich adjusters on carb are.I won't just start turning on set screws.Any helpful advice I will thankfull.Other than that the motor runs great.150+ pounds per cylinder.I need advice.Thanx Dan
 
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HillbillyDan35

Recruit
Joined
Aug 15, 2006
Messages
2
Re: 79 Merc 40 hp Rich on low rpm sometimes falls on face at high rpm

OK,I turned set screw on front of carb.Clockwise - Idles great will troll all day.Motor stalls out when I open it up.Counter clockwise - Idles real rough & will stall if you don't baby sit throttle,But full throttle is fine. I played with it for 2 hours on water .Can't find a happy medium.Also,When I took cover off motor,It seemed to run better.Like it's starving for air.Any suggestions will be helpful. I think it is in the carb,But I'm not sure.Thanx Dan
 
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