Mariner 9.9 4stoke idle help

[Saltyfishnchips]

Hi all ! Just purchased a boat and motor from storage . It has a mariner 9.9 4 stroke . I have owned many 2 stroke but never a 4 . The motor hadnt been ran since last summer and the owner had said it ran but not quite right . So I brought it home with a dry tank and line . I put 2 gallons of gas in and a half can of sea foam . I was suprised to find no choke . I primed to a firm bulb and gave some pulls . After six pulls it fired ,ran for a bit then stalled .(Lower unit in a large vat of water ) Started on first or second pull after that . I would let it idle for abit then attempt to engage it into gear . Each time it would stall out . I gave up for the night and the next day tried again . Doing a very slow turn of the handle to engage I could keep it going but when I tried a higher rpm it would stall . I noticed that the idle would start out higher rpm and decrease as it warmed . Is this how this motor should idle ? Also any one know why it is stalling at higher thottle ? Last question . What is the green light next to the pull rope for ? Thanks for help

 

[milehighboater]

Re: Mariner 9.9 4stoke idle help

I have had some issues with tuning with seafoam is still in the gas on smaller 4 strokes. I don't recomend doing any adjustments until it is just running on regular premix. I don't know much about that motor though. Good luck.

 

[CharlieB]

Re: Mariner 9.9 4stoke idle help

Depending on the model/year, the 9.9 4-strokes have three different carbs, the common fault was/is dirty idle fuel passages restricting fuel flow and/or a dirty check valve on the accelerator pump.

Some of these carbs have an electric 'enrichener' that turns down/off , heated by the charging system once the motor is running.

On the very top of the carb there is a flat plate gasketed to the carb covering most of these idle fuel passages. You may find one or more of these TINY holes that pass fuel into the top of the carb throat plugged/restricted. Be VERY CAREFUL cleaning these holes as it is too easy to enlarge them! Use the spray tube on a can of carb cleaner and watch the spray, one hole at a time to see it spray into the carb throat. I keep a VERY small slender sewing needle in my kit that is smaller than these holes to rod them out if the spray pattern thru them is not good. DO NOT ENLARGE THESE HOLES!!!!!

The adjustable idle jet screw is covered by a pressed in plug which must be drilled to remove it to gain access to the jet. Once uncovered GENTLY screw it IN until lightly seated, write down the # turns and clock position of the slot so that you can put it back once finished cleaning the passages.

 

[Saltyfishnchips]

Re: Mariner 9.9 4stoke idle help

Thanks for the help . I wont be able to work on it until next monday , but I will let you know if I have luck with it !

 

[Saltyfishnchips]

Re: Mariner 9.9 4stoke idle help

I am back . O.k. , I have tore down and cleaned this carb twice now and here are the results . I learned in taking it apart that when the throttle handle is turned it acts as a primer and injects fuel into the carb . Now I know why it doesnt have a choke or primer . The motor starts up great and idles great . It runs real well up to half throttle . On my last trip out I ran it without the cowling on and I used my thumb against the air intake to adjust the amount of air . I found that if I half covered it ,the motor would run would run fine past the half throttle stall out point I was getting earlier . It still ran good at low speed and idle with the half covered intake . I want to cheat at this and just put something over the air intake and call it done but I know this isnt right . I didnt see a plug area on or in the carb where the jet adjust would be . There is a tall screw on the top of the carb at the rear where the carb attaches to the block . Would this be the adjustment screw ? I didnt put the year of the motor in my first post . It is a 1996 .

 

[CharlieB]

Re: Mariner 9.9 4stoke idle help

Restricting the air flow as you describe is actually functioning just like the old style butterfly choke. Your are artificially raising air speed thru the carb, forcing a greater air pressure difference inside/outside the carb and drawing MORE fuel thru the main jet.

Whole you had the carb apart did you remove and clean the main jet?

Float level must be adjusted correctly, too low and the more will run lean, possibly causing this problem.

Is there any air leaks in any of the gaskets?

While running, spray flammable gas such as carb cleaner on the carb gasket, and intake gasket. If the engine speed changes then you have found your intake leak.