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3 cylinder 50 Idling to fast

D

d18

Member
Hi all...
I have a 1986 mercury 50hp 3 cylinder that idles to fast, my question is, where do I adjust the idle?
Some videos I've watched talk about adjusting the timing advance, is this correct?

Thanks...

Troy
 
Disconnect the throttle cable before doing anything else- if it settles down, make sure the cable hasn't been damaged or may be restricted from moving in its whole range.

Don't default to messing with the idle- you have three carbs and they need to be synchronized. If someone else messed with them, find someone else and make sure they have a manometer, so the carbs can be set correctly.

If it ran well last year, what makes you think anything needs to be readjusted?
 
jimn said:
Disconnect the throttle cable before doing anything else- if it settles down, make sure the cable hasn't been damaged or may be restricted from moving in its whole range.

Don't default to messing with the idle- you have three carbs and they need to be synchronized. If someone else messed with them, find someone else and make sure they have a manometer, so the carbs can be set correctly.

If it ran well last year, what makes you think anything needs to be readjusted?
Click to expand...
I will definitely disconnect the throttle cable as first test.
It has always idled fast, I just haven't been using it for several years, putting it back in service this year.
This model is 3 cylinder, but 2 carbs on a manifold, just an update.

Thanks
 
d18 said:
I will definitely disconnect the throttle cable as first test.
It has always idled fast, I just haven't been using it for several years, putting it back in service this year.
This model is 3 cylinder, but 2 carbs on a manifold, just an update.

Thanks
Click to expand...
As long as it has more than one carb, my recommendation about synchronization stands. However, the throttle cable is still my first choice- look for info about how far the throttle plates should be opened at idle- if one or both are open too far, it will idle too fast.
 
I doubt you use a manometer on a 2 stroke motor , if it is a 2 stroke.-----Throttle plates should be closed at idle on a 2 stroke.
 
I checked my '86 - 60 carb sycronization with one of these...

Edelbrock 4025 Uni-Syn Carburetor Balancing Instrument​


sync.jpg
 
This YouTube is about motorcycles but it all the info apples to outboards...
Click to expand...


Not really as those tools are for 4 stroke engines..cant see how you used the Edelbrock tool your carbs as both carbs feed middle cylinder. I have the same set of gauges as only technician around here that will touch a Zuki
 
You use the Uni-Syn by moving it from throut to throut checking the red plastic float level. The Youtube video is for you to understand the concepts of carb syncronization.

All multi carb engines need to have the carbs sycronized, especial the Merc where one of the cylinder is sharing both carbs.

There is no mystery here, it is just fluid dynamics. His two carb are probably just fine since they are coupled together between each other, but it never hurts to check.

The interconnection could of been damage when the carbs were being removed for cleaned...
 
I have probably taken you down a rabbit hole, that is not necessary. But, an asenteric check and an increased knowledge base never hurts.
 
Throttle plates are CLOSED at idle.----Same amount of air goes through them.----Idle RPM is adjusted with spark timing.-----On the 2 carburetor 3 cylinder motor it is the reed blocks that feed the center cylinder.
 
FishinLite said:
You use the Uni-Syn by moving it from throut to throut checking the red plastic float level. The Youtube video is for you to understand the concepts of carb syncronization.

All multi carb engines need to have the carbs sycronized, especial the Merc where one of the cylinder is sharing both carbs.

There is no mystery here, it is just fluid dynamics. His two carb are probably just fine since they are coupled together between each other, but it never hurts to check.

The interconnection could of been damage when the carbs were being removed for cleaned...
Click to expand...
more of a 4 strk thing. never seen it done on 2 strk.
 
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