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  1. #1

    Default Nissan 9.8 outboard issues

    We received a 9.8 outboard when we purchase our cottage and it's been giving us nothing but trouble.

    We brought it home this winter, completely disassembled and cleaned the carb, and then it ran like a champ in the backyard. Took it up to the lake a few weeks ago and by the time it was mounted on the aluminum it started to have the same issue...

    It starts every single time, one pull with the choke on...5-10 seconds after the choke is turned off it sputters and dies. We've tried multiple hoses, replced the bulb on one to be sure, brand new plugs, and brand new gas... Once it dies, I can't squeeze any more gas into the carb and the carb definitely has gas in it. I can't for the life of me figure out what else it could be, and it confuses the hell out of me that it starts without fail every single time.

    thanks

  2. #2

    Default Re: Nissan 9.8 outboard issues

    I should also point out that I can keep it running by pulling the choke when it starts to lose rpm...and yes, I have tried adjusting the air/fuel mixture screw at about 20 different settings.

  3. #3
    Join Date
    Jun 2007
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    TAMPA, FL, USA
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    Default Re: Nissan 9.8 outboard issues

    "completely disassembled and cleaned the carb, and then it ran like a champ"

    Think about it...Here is the same type of situation below.

    I have a tire that keeps losing air. I pulled a nail out of it, patched it and it stopped losing air for a while. Now it is going flat again. What could it be?
    Elvin
    Solution One Maritime

  4. #4

    Default Re: Nissan 9.8 outboard issues

    Sure...but it ran like a champ for 15 minutes at home...then not at the lake. I did remove and clean/check the carb three times in one day with no change in the result at all. The thing is as clean as a whistle. If I understand your analogy correctly, it only makes sense if it started acting up after a period of time.

    Does this sound like a definite carb issue...or are there other things i should check?

  5. #5
    Join Date
    Mar 2010
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    Buffalo, NY, USA
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    Default Re: Nissan 9.8 outboard issues

    Yes, it is most likely (odds are over 90%) a carb problem. When you noted "I should also point out that I can keep it running by pulling the choke when it starts to lose rpm", that indicates that the motor is suffering from a too-lean condition. I would revisit the carb cleaning. In order for the carb to cleaned thoroughly, it must be completely disassembled (including jets and emulsion tube), and submerged in real carb cleaner such as Tyme, for about 4 hours at room temperature, then blown clear with either compressed air or carb spray.

    When you note "I have tried adjusting the air/fuel mixture screw at about 20 different settings.", that indicates to me that you don't understand how a pilot screw is supposed to be adjusted, nor the purpose of that adjustment. Assuming that you are in North America, it also tells me that you have an older 2-stroke motor, such as the NS9.8B, because, if you had a newer 4-stroke, such as the NSF9.8A3, you would not have access to a pilot screw... That tells me that the fuel pump is built onto the carb. Did you service that pump as well as cleaning out the carb bowl? If not, junk in that pump could have re-contaminated the carb when you tested the motor.

    When a carbed outboard motor of any brand is stored more than a week without emptying the carb, you can expect varnishing residue from the fuel. So... even if you did successfully fix the problem when you tested in your yard, it is entirely possible that, if a week or 2 elapsed from when you tested, and you didn't drain the carb, you once again need to go through the carb.

    Full information on pilot and other carb adjustments is in the Factory service manual, available from any dealer (including me). You will need to specify the model in order to get the correct manual.
    Paul
    Buffalo NY USA

  6. #6

    Default Re: Nissan 9.8 outboard issues

    Thank you for taking the time to answer with detail. Yes, it is a 2 stroke 9.8.

    Yes, you are correct that I do not completely understand how the pilot screw functions. I thought that maybe the mixture was off since the choke can keep the engine running, I'm learning...

    I'll remove the carb and follow your instructions. Wish me luck!

  7. #7

    Default Re: Nissan 9.8 outboard issues

    For the sake of learning, can someone explain why it will start every time without problem?

  8. #8
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    Default Re: Nissan 9.8 outboard issues

    The choke...
    Elvin
    Solution One Maritime

  9. #9
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    Default Re: Nissan 9.8 outboard issues

    Right... If the carb is too lean, adding choke can add enough fuel to run. Sounds like you need to go the carb again. Keep in mind that running on muffs does not load the motor much... so even if you get it to "run" at home, it's not under full load. A loaded motor will demand correct mixture to keep running... which brings us back to the carb again. Pay particular attention to making sure the low-speed and pilot circuits are cleaned well.
    Paul
    Buffalo NY USA

  10. #10

    Default Re: Nissan 9.8 outboard issues

    Thanks guys, I appreciate it! I would much rather learn and understand what's going on than simply just get told what I should do. Motors weren't something I learned much about growing up... I'll give it a good soak and clean and then blow it out with air and hopefully that will be it. The whole engine was fully serviced a little over a year ago and the entire thing looks practically brand new under the cover so I'm optimistic.

  11. #11
    Join Date
    Apr 2011
    Location
    Western Australia
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    129

    Default Re: Nissan 9.8 outboard issues

    It is definitely running lean. Did you manage to really clean the jets and emulsion tube? If the Carb on your Tohatsu is anything like the jets I've adjusted on every bike I've owned, the fuel/air mixture screw only needs to be about one and a half turns out. Any real variation from this would usually mean the jets are the wrong size but as your jets have not been changed, you should find that setting to be close. Paul and Elvin, please correct me if I am wrong. I would not want to lead anyone up the garden path! One thing I should mention please be very careful when seating the mixture screw. Do not force it at all. Just lightly screw it all the way in until it lightly seats and then start winding it out. Any force will stuff up the mixture screw.
    Good luck with learning about motors, but beware, it can be addictive. Enjoy the learning curve.
    Good luck with the motor and keep us updated.
    Scott.

  12. #12
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    Default Re: Nissan 9.8 outboard issues

    This applies to four-strokes........................

    There is no air mixture screw available to adjust on that model due to the EPA being afraid of tampering. That doesn't mean that there isn't one...There is...It's just not visible and for the record, never needs to need to be adjusted.

    Side note: Many people want to adjust the air mixture screw to compensate for "other" problems. Leave it alone and fix the actual problem.
    Elvin
    Solution One Maritime

  13. #13

    Default Re: Nissan 9.8 outboard issues

    Update time...

    I brought it home again, completely disassembled and soaked the carb, then blew every opening i could find out with air. She seems to be now running great...

    As for the air mixture screw...mine is most definitely visible, should i follow the advice from above?

    Thanks a ton guys!

  14. #14
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    Default Re: Nissan 9.8 outboard issues

    There is a science and an art to adjusting the pilot screw. It should be best done by someone with experience; Failing that... a good ear, a precise shop tach, and the procedure from the Factory service manual should be more than adequate.
    Paul
    Buffalo NY USA

  15. #15
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    Default Re: Nissan 9.8 outboard issues

    If you have a 4-stroke the air mixture screw is not visible...Unless someone has drilled into the carburetor to expose it. Even then, it should not be touched...Unless the previous idiot who owned the engine screwed it up already.
    Elvin
    Solution One Maritime

  16. #16

    Default Re: Nissan 9.8 outboard issues

    Gotcha...and it's a 2 stroke. Unfortunately i did remove the screw when i took apart the carb. I'll pay a visit to my lake's marina this weekend and see if he's got the service manual.

  17. #17
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    Default Re: Nissan 9.8 outboard issues

    Bryan,
    In order to set a 2-stroke pilot acceptably, you will need a good shop tach and a warmed-up motor. Seat the screw gently (for an index), open it up about 2 turns, start and idle the motor in gear. Make sure you are fully warmed up. Then...

    Here is an old-timey technique that many seasoned techs use:
    Check/adjust idle stop screw to specs. Adjust the pilot about 1/4 turn. Check tach. If the RPM is down, adjust the pilot in the opposite direction. Readjust idle stop. Repeat as many times as necessary to get the best, smoothest, fastest idle (in specs) at the lowest idle stop setting. Once you have found the highest idle (with lowest idle stop setting) of the pilot, you are very close. Then richen (open) the pilot screw about 1/16-1/8 turn. Verify idle stop again. Done.
    Paul
    Buffalo NY USA

  18. #18

    Default Tohatsu 9.8 outboard issues

    Hi - I read with great interest about the Carb/Idle problems with the 9.8hp. I originaly thought that I was alone with my frustrations. Now reading the entries I am pleased to see a solution.

    I do not just have one engine to maintain though. Currently I have twenty eight 9.8hp, eight 8hp and two 15hp Tohatsu to contend with. The fleet is part of a high usage group belonging to a charter yacht company based in the Caribbean. So they have a hard life as any hire or charter item would do. Some many months ago we had a visit from the Tohatsu engineer from the main building plant. Unfortunately his English was not up to par and my Japanese zero. So the re-occurring idle problem remained and the manufacturer unaware. Some thing I think should be addressed

    It would appear that even fresh out of the box - the 9.8hp will run and fire up first pull, but not long after that start to suffer low idle issues. In turn the 'crash' box gear change can be heard around the dock as the idle has been set and reset too high, just so the customer doesn't cut out leaving the dock or yacht. I do have a fairly talented self taught team of one out board mechanic, but even after numerous carb strips and rebuilds the problem still reoccurs. So I am very interested to try the soaking and new jet solution. Having read the previous posts, its not to far from what we have already tried. So I find my self questioning the oil/gas ratio as a lean mix suggested in another post is some thing we do not do. In fact I would say we run our outboards fairly rich.
    Any other suggestions or tips would be gratefully received. Even if your repeating earlier posts.

    Another Tohatsu problem is with the 15hp. We have had numerous problems with the CD unit. At $300 to replace, the 15hp's are not proving to be reliable or cheap to maintain. They are terribly hard to start. If the choke is not immediately pushed backed in after a successful start it cuts out. Even the newest one to fleet came out of the box and has these traits. Any suggestions?

    I should also mention there is no Tohatsu dealer on this island in the sun - so everything is imported, including spares. So all commissioning is also performed in house.
    Thank you for your time reading this.

  19. #19
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    Default Re: Nissan 9.8 outboard issues

    The Mooring's?
    Elvin
    Solution One Maritime

  20. #20

    Default 9.8 outboard issues

    No - not the moorings - small independant - but moorings does have a massive fleet of tohatsu in thie portfolio.

  21. #21
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    Mar 2010
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    Default Re: 9.8 outboard issues

    Ross,

    Although the 2-stroke 8/9.8B and 15D2 have been unavailable in the US for some years (due to emissions laws), we still have them in use, particularly when they are run in cold fresh water, because it's less corrosive, and the motors are very durable. We see that the newer 4-stroke carbs have a lot more problems, which are caused by a combination of the poor quality of fuel available, and varnishing (caused by not running the carb dry at the end of the day). I believe that the older-technology 2-stroke carbs are a little "looser" and have larger, lower-velocity passages, which are less susceptible to minor varnishing.

    We have had mixed results with "fuel stabilizers", with the one notable exception of the K-100 products, which are made locally. We have also concluded that most of the "stabilizers" usually have a high percentage of alcohol, which does not help the situation with our E-10 and E-15 fuels. Regardless, we do see benefits from using the K-100MG product on sailboat aux motors, where the fuel often sits for 30 days. Fresh fuel is always the best. We also run water-separating filters whenever possible.

    In the vast majority of poor idling cases (assuming the rest of the motor is healthy and the fuel is good), we have had good results using real carb dip, such as the Tyme brand from CRC (available here in 1- and 5-gallon cans): We do a complete carb strip (including jets and emulsion tube (nozzle), followed by a 4-hour room temperature (70-degree F) submersion in Tyme. We then blow out all passages liberally with the spray-type carb cleaner to physically remove what was dissolved in the "bath". In at least 75% of cases, we do not need to install a new carb kit, unless the needle is damaged/worn, or there is other age-related wear-and-tear.

    2-stroke fuelil ratios will affect idle on many motors, with more oil (richer) having an effect similar to richening the pilot screw. This can cause an operator to change the adjustment of the pilot slightly -- which then presents a problem if a subsequent load of fuel has a slightly different fuelil ratio. The best situation is where the fuel and oil is mixed well and consistently.
    Paul
    Buffalo NY USA

  22. #22
    Join Date
    Apr 2011
    Location
    Western Australia
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    129

    Default Re: Nissan 9.8 outboard issues

    Hi Paul.
    When using a product like Tyme, do you have to take of all of the rubber 'O' rings and small gaskets or can you leave them on? I have only ever used spray carby cleaner but I would like to give all of my carbs a good soak.
    Hey Ross. I'm sure one of the guys on this forum would love to come to the Caribbean to give your engines a once over!
    Elvin - Thanks for keeping an eye on my thread. Like I said, I would hate to lead anyone astray.
    Best regards,
    Scott.

  23. #23
    Join Date
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    Default Re: Nissan 9.8 outboard issues

    The hard plastic linkages can remain; the internal gaskets and o-ring materials have to be removed.
    Paul
    Buffalo NY USA

  24. #24
    Join Date
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    Western Australia
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    Default Re: Nissan 9.8 outboard issues

    Excellent! Thanks Paul.

  25. #25

    Default 9.8 outboard issues

    Thank you for your input guys -

  26. #26
    Join Date
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    Default Re: Tohatsu 9.8 outboard issues

    Quote Originally Posted by Ross Keeble View Post
    Hi - I read with great interest about the Carb/Idle problems with the 9.8hp. I originaly thought that I was alone with my frustrations. Now reading the entries I am pleased to see a solution.

    I do not just have one engine to maintain though. Currently I have twenty eight 9.8hp, eight 8hp and two 15hp Tohatsu to contend with. The fleet is part of a high usage group belonging to a charter yacht company based in the Caribbean. So they have a hard life as any hire or charter item would do. Some many months ago we had a visit from the Tohatsu engineer from the main building plant. Unfortunately his English was not up to par and my Japanese zero. So the re-occurring idle problem remained and the manufacturer unaware. Some thing I think should be addressed

    It would appear that even fresh out of the box - the 9.8hp will run and fire up first pull, but not long after that start to suffer low idle issues. In turn the 'crash' box gear change can be heard around the dock as the idle has been set and reset too high, just so the customer doesn't cut out leaving the dock or yacht. I do have a fairly talented self taught team of one out board mechanic, but even after numerous carb strips and rebuilds the problem still reoccurs. So I am very interested to try the soaking and new jet solution. Having read the previous posts, its not to far from what we have already tried. So I find my self questioning the oil/gas ratio as a lean mix suggested in another post is some thing we do not do. In fact I would say we run our outboards fairly rich.
    Any other suggestions or tips would be gratefully received. Even if your repeating earlier posts.

    Another Tohatsu problem is with the 15hp. We have had numerous problems with the CD unit. At $300 to replace, the 15hp's are not proving to be reliable or cheap to maintain. They are terribly hard to start. If the choke is not immediately pushed backed in after a successful start it cuts out. Even the newest one to fleet came out of the box and has these traits. Any suggestions?

    I should also mention there is no Tohatsu dealer on this island in the sun - so everything is imported, including spares. So all commissioning is also performed in house.
    Thank you for your time reading this.
    There has not been any CD failures on the 15/20 frame that we have seen in the U.S. It could either be a bad production run, bad ground or faulty diagnoses. If you have the 2-stroke that goes double. Assuming you are getting your parts and support through Budget(Good luck with that ) You might want to consider purchasing your parts from the U.S. They cost less and you can get anything within a week. If you need a contact for parts or tech help let me know and I will put you in touch with the right person.
    Elvin
    Solution One Maritime

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