1989 90Hp Mariner smoking a little too much

[kriphead]

I have a 1989 90hp 3 cyl motor which workes fine, but making a little too much smoke after my taste. A researched and figured it could be because of too rich mixture. I then went out on the lake to adjust the idle screws (now I says screws, since I think there are 3????) Please confirm.

I ended up not really messing with them since I could not see any change, but might still have turned 1 or 2 of them slightly off the setting they were on before. It sounds fine, but would like to know the bench mark the idle adjustment screws should be at.

The 3 screws are all turned 2 full rounds counter clockwise from lightly seated. I believe by turning them all slightly clockwise, i lean the mixture, and the smoke should be less.

I know that running slightly rich is better than lean, but would like to turn the smoke down a bit. Let me know if there is a recommended setting to take aim at to at least start with.

Thanks

 

[latin monkey]

Re: 1989 90Hp Mariner smoking a little too much

at what ratio are you mixing your gas?

 

[Dave1027]

Re: 1989 90Hp Mariner smoking a little too much

It's an autoblend oiling system.

OP, you need to determine how much oil the system is putting in. It's not rocket science. You simply put some marks on the side of the oil tank so you can determine how much oil it uses. Compare that with how much gas you are using. It should be about 1 part oil to 50 parts gas. If it's putting too much oil then it can be adjusted by undoing and turning the variable control rod. Don't blindly reduce the oil. You need to know the ratio.

 

[kriphead]

Re: 1989 90Hp Mariner smoking a little too much

Well, I am not really worried about the oil. As far as I understand, I am adjusting air/gas mix, and this is where I am talking about Idle and white smoke being slightly too much. On the idling screws, I am not adjusting oil, am I???

What I wanted to know was:

1) is it true that there are 3 idling adjustment screws? If yes, I assume I have to adjust all 3 of them until I have the best idle "sound".

By reading I understand that I have to turn (1 at a time) the screw as much counter clock wise until the cylinder misfires or something, then go completely the other way, clockwise until the cylinder starts to misfire again, and then turn out the screw ???? (this is where I would like to know what the bench mark is? is it ? turn, 1/4 turn or 1 full turn etc.

I assume I do this on all 3? And, again it is better to be slightly on the rich side than lean??

Let me know

thanks

 

[mrcrankypants]

Re: 1989 90Hp Mariner smoking a little too much

follow the link I posted sport jet 120 pdf manual it show how to set the screws http://motorka.org/doc/mercury/service_manual/jet/SJ120xr2_858804/cover.pdf go to p4 and click the section you want.

 

[109jb]

Re: 1989 90Hp Mariner smoking a little too much

If the engine runs then you don't really need to know the initial setting. The initial setting is just a point where the engine should run. Since yours already runs you are past needing the initial setting. Do the following:

1. Start engine and let it warm up and let it idle.
2. One carburetor at a time, slowly turn the idle adjustment screw counter-clockwise (rich) until the engine just starts to stumble.
3. while counting the number of turns, slowly turn the screw clockwise (lean) until the engine starts to stumble.
4. divide the number of turns by 2 and turn the screw counter-clockwise that amount
5. repeat for each idle screw.

Having said that, Dave1027 is right. You need to check the oil consumption to see if it is right. If the engine is running right as you say it is, the smoke is likely from excess oil consumption.

 

[kriphead]

Re: 1989 90Hp Mariner smoking a little too much

Thanks. I will try that. Might want to check my oil consumption as well.