'94 evinrude 120 carb question

SawBum

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Jul 4, 2007
Messages
24
Hey guy's, I have been fighting a top end running prob. for sometime now, she leans out (looses power) at full throttle, runs great at mid-range, I went through a lot of trouble and removed my center console to remove the fuel tank because I thought it had a fuel filter sock in the tank, NOPE, just a tube with a pick up screen that is not removable. I have done a lot to find my problem, ck for air leaks, replaced primer bulb, inspected vacume lines, cleaned carbs, replaced in line fuel filter, tear down VRO pump and inspect(looked real good, soft diaphragms) the oil side of the VRO was bypassed a long time ago and Joe Reeves confirmed that it was done correctly. I am back into the carbs to double ck my work and I noticed something, on the outside body of the carb at about 11 o'clock there is a screw, it seems to be an adjustment screw since it feels like a spring is behind it, the body that the screw is in has a small hole that is open to outside air, could this be a atmospheric port? if so, ALL 4 screws are completly closed, they are not removable if you back them out (or so it seemed, I did not want to forse them since the carbs are plastic. any advise on the purpose of these screws and anything alse would be nice, Thanks, Ron
 

Walker

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Jun 15, 2002
Messages
3,085
Re: '94 evinrude 120 carb question

Those are air metering screws as opposed to fuel metering screws on the older type carbs. The initial factory setting was 2.5 turns out but I'm pretty sure a service bulletin came out recommending more. Can't, off the top of my head remember what it was. Anyway, they should not effect high rpm running.
 

SawBum

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Jul 4, 2007
Messages
24
Re: '94 evinrude 120 carb question

Those are air metering screws as opposed to fuel metering screws on the older type carbs. The initial factory setting was 2.5 turns out but I'm pretty sure a service bulletin came out recommending more. Can't, off the top of my head remember what it was. Anyway, they should not effect high rpm running.


I understand the air mixture for proper atomizing of fuel at low speeds, but this motor idles like a dream, runs perfect all thru mid range up to about 4200 RPM, then if you nail the throttle to WOT, it leans out and looses power. with these needles shut all of the way, I would think it would idle poorly and have bad response???:confused:
 

reeldutch

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Feb 2, 2004
Messages
1,340
Re: '94 evinrude 120 carb question

does it have enough fuel pressure at wot?
 

CARDNAL98

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Joined
Feb 5, 2008
Messages
21
Re: '94 evinrude 120 carb question

sounds like you have the same prob my buddy brian had with his outboard he just put on a new fuel pump and motors runs great at full speed he fuel pump was not getting enough fuel to motor that is why he could not get up to speed hope this will work for you good luck
 
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