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Mariner outboard 100hp ---giving problems

  • 07-06-2012 9:41pm
    #1
    Registered Users Posts: 108 ✭✭


    Can anyone help me?? i have a mariner 100hp longshaft. starts perfect but when i go to give it a nice bit of throttle it starts choking like and ive to pull back the throttle.its becoming a pain in the a*se now. ive tried a few different things to try solve it but ive yet to figure it out...please anyone with any ideas or information please let me know .cheers


Comments

  • Moderators, Motoring & Transport Moderators, Sports Moderators Posts: 6,317 Mod ✭✭✭✭fergal.b


    It sounds like fuel starvation

    1) if you pump the primer bulb will it pick up

    2) check the air vent is open on the tank

    3) check the fuel filter and pump

    4) is it firing on all cylinders

    Spray a bit of carb cleaner into the carb and see if that helps.

    .


  • Registered Users Posts: 605 ✭✭✭breghall


    when it's starts to act up when throttling, bump the choke in , if this helps then you need to clean the carbs.


  • Registered Users Posts: 2,369 ✭✭✭Skuxx


    Had a problem like this before with a 120hp mercuary force, would be fine while ticking over in neutral, into gear than it she'd struggle to keep running, turned out to be the carb, as the lads said!!


  • Registered Users Posts: 108 ✭✭den1982


    checked spark,its ok...priming the fuel primer makes no difference..sprayin fuel in to carb makes no difference either. This is the way this engine has been with 10 years, starts first pick everytime,runs lovely and smooth always til u put the throttle to full speed and then she limits at roughly 2500rpm. When i bring throttle back to half way, she will run away again pure smooth but if u go past half throttle ,its like a limiter kicks in and no matter how far i push the throttle it will not pass the 2500rpm mark.....

    PS i removed the 2stroke bottle and pumps out of this engine when i got it 10 yrs ago.Do ye think this would of affected it??


  • Registered Users Posts: 605 ✭✭✭breghall


    Den ,
    Am i right here , you have this issue now for 10 years:eek:
    you removed the auto mix 10 yrs ago and it's been like this since??

    I still say clean the carbs as you may have dirty high speed jets which would cause this prob.

    maybe you may not be runnning on all cylinders.
    when the engine is running , use a pliers with a good plastic well insulated grip and remove the lead off each spark plug one at a time. the engine should act up like it's dying, and you should notice a difference when putting the lead back in place. If nothing happens when you pull a spark lead off a plug then you have a prob with the cylinder either not getting fuel or spark.

    Mix is 50:1 too.


    also post your engine serial number here so we know what motor we're exactly dealing with here (stamp on the port side of the transom mounting bracket)


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  • Moderators, Motoring & Transport Moderators, Sports Moderators Posts: 6,317 Mod ✭✭✭✭fergal.b


    Depending on the year you could also have a faulty temp sensor this will think the engine is getting hot and stop it from going into high revs.


  • Registered Users Posts: 533 ✭✭✭Daibheid


    When the automixing oil system was removed the sensor to warn of low oil level just might be the source of your problem. Some 2 strokes will limit the revs when the oil level drops low - not enough to present you getting home but enough to make sure it gets your attention. I learned this the hard way in the middle of a very rough Blasket Sound some years ago. Sometimes the low level will also sound a warning horn.

    I couldn't imagine living with an engine behaving as described for years but you'd better find out whether the level sensor is still connected and if not what the engine's control unit will see instead. I'm betting it's designed to fail safe, i.e. if there's no sensor connection it'll assume the sensor is defective and play safe by limiting the revs.

    I'm assuming the oil injection ports on each carb were blanked off!


  • Registered Users Posts: 2 outboardbored


    Hi, new to the forum.
    Been out today in sunny cornwall with my mariner 100 2 stroke 1990.
    As one of the other members talked about I have a similar problem with what appears to be fuel starvation. Starts up on first turn of the key. Will pull away and get my rib up on the plane but wont rev over 4000 (ish) will then out of nowhere start to run properly at full power for 10 secs or so then drop back to hardly able to plane at all. Pushing in the choke instantly helps for a few seconds, adding more throttle makes no difference when the symptoms are showing, if anything makes it worse. The bulb appears to go soft during these events.
    Portable fuel tank is clean and the feed pipe into the tank is intact.
    I've replaced all the fuel lines and fitted a new inline water separator and filter.
    New plugs of the correct type also.

    Any ideas?


  • Moderators, Motoring & Transport Moderators, Sports Moderators Posts: 6,317 Mod ✭✭✭✭fergal.b


    Welcome to the forum, Is there any chance the breather valve on the tank is closed.




    .


  • Registered Users Posts: 2 outboardbored


    thanks for the reply, just checked it again, it wasn't totally open but can't really say the rubber washer was in friction with the tank. Possibly be that considering the soft bulb.

    Going to take it out again tomorrow and see. When it's running well it's very good!
    My local outboard specialist had the engine running at full revs in a tank (not on a dyno) and couldn't replicate the problem.

    Simon


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  • Moderators, Motoring & Transport Moderators, Sports Moderators Posts: 6,317 Mod ✭✭✭✭fergal.b


    I have also seen the valve in the bulb getting blocked up and causing the same problem so if it turns out not to be the one on the tank try that.
    Good luck.



    .


  • Registered Users Posts: 410 ✭✭megafan


    den1982 wrote: »
    Can anyone help me?? i have a mariner 100hp longshaft. starts perfect but when i go to give it a nice bit of throttle it starts choking like and ive to pull back the throttle.its becoming a pain in the a*se now. ive tried a few different things to try solve it but ive yet to figure it out...please anyone with any ideas or information please let me know .cheers


    Den1982..... Have you solved your problem? if not another idea.... Does your outboard have HT leads? if so they may be breaking down.... at tick over fine but when engine under load spark will take easiest route & leak through HT lead/plug cap causing misfire/poor running on one or more cylinders.... Easy to happen an engine in damp salty enviorment...


    good luck!


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