Idling

[ngentile]

Hello all,

RE: my 1987 Mercury Mariner 25hp outboard:

What I'm finding is that my engine idles perfectly in the water when I first launch. Then after I open it up and run it a few times around the lake it starts idleing very rough and will konk out and idle rough for the rest of the day. Why would a warmed up engine konk out? When its cool it itdles fine?? I can't imagine the carburator having anything to do with this.

Thanks

 

[SC1650]

Re: Idling

My guess is it is getting to much fuel when it gets warm. Most engines use extra fuel when they are cold to keep the idle going. Once they warm up the choke or the electronics cause the fuel to lean out. In your case there is no way to lean it out automatically. Therefore, I believe that you have to adjust the carburator. You may have a float levels set to high or the idle mixture may have to be turned in to lean it out a little so it will run when it is warm.

 

[ngentile]

Re: Idling

How do I adjust float levels or idle mixtures???

I know how to adjust fuel air ratio (screw on top of the carb)...

And when you use the term "lean out" you mean more gas less air correct?

 

[SC1650]

Re: Idling

How do I adjust float levels or idle mixtures???

I know how to adjust fuel air ratio (screw on top of the carb)...

And when you use the term "lean out" you mean more gas less air correct?

Float level is adjusted by taking the bowl off on the bottom of the carb. You would need a new gasket to do this. You would also need to take the carb off of the motor. It is a tight fit.

What screw on top of the carb are dealing with?? The fuel air mixture is the screw on the right side of the carb near the top. It has a spring on it. You screw it in to lean the mixture. Out to richen the mixture.



And when you use the term "lean out" you mean more gas less air correct?

NO!!!!! When you lean it out you are giving it more air and less fuel.

Hope this helps.

 

[ngentile]

Re: Idling

Ok firstly I'm very familiar with all of the parts of my carb. All the gaskets are aok.

"Adjust the float" are we trying to make the float higher or lower?

Could this rough idle be a result of the mechanical fuel pump needing to be rebuilt?

I need to also add that I cleaned the carb so you can eat off it and the engine will run like a bat out of hell when you open it up full throttle.

Thanks

 

[SC1650]

Re: Idling

Ok firstly I'm very familiar with all of the parts of my carb. All the gaskets are aok.

"Adjust the float" are we trying to make the float higher or lower?

Could this rough idle be a result of the mechanical fuel pump needing to be rebuilt?

I need to also add that I cleaned the carb so you can eat off it and the engine will run like a bat out of hell when you open it up full throttle.

Thanks

If you are familiar with all the parts to the carb then you should know where the adjustment screw for the idle is located and you should know where the float is located.

You can clean anything off on the outside and get it to look great. It is the insides that usually are the culprit. Did you have the carb apart????

Remember that any time you open the throttle wide open it will take care of any extra fuel going to the engine. It is at idle that extra fuel poses a problem.

I doubt that the fuel pump could be the problem but I've been known to be wrong before. Fuel pumps, when bad, usually will not give you enough fuel to go full throttle for any length of time. It will lack fuel and misfire or slow in RPM's.

 

[ngentile]

Re: Idling

I apologize.. I wasn't clear in previous posts... Yes I know where the rich/lean screw is located yes I know where the float bowl is located and yes I have taken my carb apart more times than I know. Now about the float, I can picture the inside of my float bowl in my head from the last time I took it apart however, I can't remember any sort of adjustment in the float bowl compartment... At anyrate I did take the boat out today and the same thing happened.. Its very annoying... However I did notice that after going full trottle for a good stretch and then when i go a little faster than idle speed for a little bit engine cools and it idles fine. Its only right when I come out full throttle to idle that the engine will konk out. It's especially annoying when I'm pulling up to the dock and try to kick it into reverse it and it dies.

Tks