mercury 9.9 (1980? no serial number)

[joecefnhedog]

Hello,

My outboard usually starts first pull and runs maybe a little rough in idle but didn't stall. There have been two occasions where I would pull it too slowly and it would splutter and die (then it would take numerous pulls and waiting to get it going again).

The carb has been cleaned recently, new sparks and ht leads.

Yesterday I tried adjusting the screw near the red arrow in my picture, and it wouldnt stay in idle at all (kept stalling). I had also just added some two stroke oil into some fresh petrol and hadnt mixed it so well, could this have made it cut out in idle?.

I really wanted to adjust the shaft throttle (blue arrow on my picture) but I was expecting a screw to adjust, does anyone know how to adjust this for idle.

I was looking at this diagram (part 3 below link) and it seems like it has a screw adjustment, could mine be missing?

https://www.perfprotech.com/mercury...1818a18b2020a20b23/assembly/496/100?model=823

The only number I can see is 37-13020.

Thanks, Joe

 

[SteveVT]

The idle mixture adjustment on a WMC type carb (as far as I know) is located directly above the throat in the front of the carb. It looks like your blue arrow is pointing to the throttle cam area, and your red arrow points to the neutral RPM adjustment -- in other words the idle speed when your motor is warmed up and in neutral gear. Not the idle speed RPM set while in forward gear, which is generally lower, and set by another screw adjustment, usually.

For the idle mixture adjustment it needs to be set with a warmed up engine in forward gear. It can be hard to see if located behind a plastic airbox, but ther is usually a removable plug in the airbox that snaps out so you can insert a screwdriver.

 

[joecefnhedog]

So the brass screw in this pic is the idle mixture? Does this need adjusting?

I wanted to increase the speed of the neutral RPM (idle speed) but the screw on the red arrow did nothing and I cant see how to adjust the blue arrow cam area.

 

[SteveVT]

Yes. that's the idle mixture screw. However:

If you don't understand 2 cycle carb tuning, I suggest you first read up on the subject instead of going at this piecemeal and by just turning random screws. You can ruin your engine if you adjust the mixture wrong.

Saying "it did nothing" is probably not accurate. What you mean is it did not solve your idling problem. Rough idling is NOT usually cured by adjusting no load idle speed. Also idle speed and mixture adjustments need to be made in sequence, and they also relate to timing with these kinds of multi purpose linkages. The rotable choke knob also interacts with the linkages.

Please take more pictures of the full stbd side of your engine showing linkages, so we can see more exactly what you have, since you don't know the year or serial number of your motor. There is likely to be another idle speed adjust screw back there, but if so, don't adjust it yet!

 

[joecefnhedog]

ya I've found the manual for the rough year and been reading through, so the idle on mine is controlled by this:

The red arrow that was in the attatched diagram, this seems to be the problem as it doesnt engage the idle throttle so hence doesnt increase the rpm. Yeah I can see the rotate choke engaging some pulleys (pulling on the idle wire (b) in the idle wire adjustment picture) but it doesnt pull it enough to engage.

yeah I'm not going to adjust that enrichment yet until I get to the bottom of this.

 

[SteveVT]

I can't help you without photos of your engine. I already have diagrams and there are plenty of variations.

You have your "rough year" engine. I can't see it so, pointless to continue without photos.

 

[SteveVT]

A.) You haven't proven you don't have an idle speed adjustment screw because you haven't shown the rest of the stbd. side side of the engine. Some idle adjust screws are toward the rear of the engine as part of the linkage system

B.)"The red arrow that was in the attatched diagram" There are lots of red arrows in your attached diagrams. Which diagrams and which arrow are you talking about. Or by "diagram" do you mean your first photo?

C.) What "pulleys" are you talking about that the rotable choke "engages"???

D.) The idle wire pulls on the timing trigger ring, which in turn is usually linked to the throttle by linkages outside of your photos, it would be in requested photos which you haven't posted.

It is a pull-only linkage. It does not push on anything. It floats free in the push direction. It should be set with a tach to the RPM spec'd in .....whatever engine you actually have's...... manual. If we had photos of your engine it would be easier to figure out just what engine you actually have, but again, we don't.

E.) "...but it doesn't pull it enough to engage." The word you use, "engage," doesn't mean anything without an explanation of what you mean by it.

If you want help, you need to be willing to help the people who want to help you.

 

[flyingscott]

Your motor is a 1986 or newer a pic of the hood will help. I believe the screw you turned is for the link and sync not the idle. Put up a pic of the side of the motor with all the linkages. Look on the motor for a disc with the serial #.

 

[joecefnhedog]

Yeah sorry about that, here are some images on the side and a picture of the hood.
I did mean the red arrow in my initial diagram. I was just trying to portray that when I turn the choke to fast, the idle wire gets pulled but doesnt quite pull the lever enough to start engaging with the cam follower.