9.9 Johnson Carb Question

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This topic contains 74 replies, has 10 voices, and was last updated by  outbdnut2 1 year, 6 months ago.

Viewing 15 posts - 46 through 60 (of 75 total)

  • outbdnut2
    US Member - 1 Year
    Replies: 1049
    Topics: 52
    #59882

    Thanks again for the info – never too much info – something here is likely to make it idle right. I have new B7 plugs in it but have some B6s I can try. I have tried the idle screw out as far as 5 turns. It does a very slight bit better 3 or 4 turns out than at the recommended one turn, and no change beyond that, but still not at all good. I’ll be digging into it again in the next couple of days. The owner needs a slow idle to back-troll for walleyes.
    Dave


    rudderless

    Replies: 109
    Topics: 5
    #59889

    Leaky crank seals and a reasonable idle are mutually exclusive…along with leaky reeds…

    If one has to open the low speed mix to compensate for air leaks..look for air leaks


    enrico-italy

    Replies: 46
    Topics: 5
    #59931

    I also had a troubly experience with this motor.

    I bought a used 1976 9.9 with minor issues ( a broken mounting screw, hard to rotate twist grip etc.) four years ago.
    The first season I had serious troubles to make it a good runner, because It "sneezed" at idle, so I opened the PW and I replaced seals (the lower one was broken) and rings.

    I found on it a couple of Champion L77JC4, so I put on it a new pair of the same plugs.

    The rebuilt engine worked better but the plugs lasts no more than two or three hours, then the spark gone.

    In the first ten hours of use it burned two sets of L77JC4 and two sets of the raccomanded plugs (UL81J)

    Then Garry or Mumbles, I don’t remember, suggest me to try NGK.

    I put on it the used set of NGK B7HS I removed from my Yamaha 30D and, (miracle!!), all the issues disapppears.

    Three years later, the 9.9 still runs well with the same plugs…


    joesnuffy

    Replies: 285
    Topics: 20
    #59944

    Thats a good point about a top or bottom seal leak could also be problem. Here is a video to watch. Checking top seal is easy.

    Hope that helps,
    Joe


    outbdnut2
    US Member - 1 Year
    Replies: 1049
    Topics: 52
    #60024

    Ok – I dug into this motor again today. Compression is fine – 90 on both cylinders.

    I think I’m getting somewhere with the carb: I pried the welch plug off the top of the carb and it gives access to the three idle holes going into the carb throat – I ran a wire through them and they are fine. I notes that only one hole is downstream of the carb throttle plate. The welch plug also gives access to the downstream side of the hole the low speed needle point sticks part way into, with the needle removed, I ran a wire through that it and it was clear, also blew carb cleaner back through the needle cavity from the small hole accessed via the welch plug. That welch plug did not give access to the needle valve’s bearing. I shined a flashlight into the needle valve’s mounting hole and could see something that looked no good at the end. With a small wire bent into a hook, I managed to pull out a small glop of what looks to be foreign material. It was "mush" when I squeezed it. It was much too small to be a partially carb cleaner dissolved bearing. It looked suspiciously like the crystalized stuff I found jamming the entire length of the float valve needle when I first took it apart, so it could have been some of that stuff that must have formed when gas (maybe gas with ethanol or some strange additive?) dried up in the carb, and the carb cleaner may have made it mushy.

    When I looked into needle valve’s mounting hole with the flashlight, at the far end I am not sure if I’m seeing a bearing or not (hard to see up there), but I think I am because I am seeing detail that looks like the radius of the bearing housing and the center hole looks like it would match the cylindrical machined surface on the needle valve assembly just behind the actual needle – seeing this hole, does this mean the bearing is in there? The hole I see in the welch plug area coming from there is much smaller for the needle tip.

    So now I will get a carbkit – need a new welch plug for starters.

    More Questions:

    1. Does a new bearing come with the Sierra Kit? The OMC kit? I think I’m seeing it in the OMC kit but not the Sierra in online photos, but it’s hard to tell. Otherwise, I see I can buy the bearing separate, but may not need it.

    2. I’d like to make sure all idle passages are really clean, and that means removing the lead shot plugs. I’ve never done that before. Any tricks to shot removal/replacement? An old Clymer manual says to pry them out with a sharp knife, awl, or other sharp instrument. To install new shot it says to use a hammer and appropriate size punch. Any really slick ways to do this that anyone has found?

    3. I’m not seeing lead shot in the carb kit photos. Can I use small fishing sinkers, squeezing them shut and , if needed, sanding the size down? I see part #0304201 lead shot at Marineengine.com for $8.93. Does that get me a few in a bag, or is that a price for one? The carb has 4 of them.

    Thanks again for all the tips. To summarize, I think I’m onto something with the bad idle finding that glop of stuff up by the needle bearing area, and likely more in passages I will get to by removing lead shot. If knowing all carb passages are clean doesn’t get me a good low idle, I will then try the spark plug electrode tips.
    Dave


    fleetwin
    US Member - 1 Year
    Replies: 2456
    Topics: 29
    #60030

    1 Sorry, but I don’t believe the bearing comes with either kit

    2 The easiest way to remove those lead shots is to drill through it with a tiny bit, then thread a screw into the shot and pull it out. I have never had any luck with the "pry it out with a knife method", but give it a try…

    3 Anything is possible, but I would just fork over the dough and use the OEM lead shot. They do install easily with a little hammer and flat punch.

    I wish I had a carb apart in front of me so I could better understand/communicate with you…I guess if the glop was past the bearing toward the mixing pocket, then yes, it may have been interfering with fuel flow. As for knowing if the bearing is in place, I guess I would just use a home made pick tool like those that have been described, and attempt to remove the old one.
    But, I guess, before doing any of this, I thought you were going to try a different carb…..Again, if the engine idles OK with a different carb, you/we will fee more confident in investing in the lead shots/bearing to repair your carb properly….Trying a different carb will only take an hour or so, and cost nothing…


    outbdnut2
    US Member - 1 Year
    Replies: 1049
    Topics: 52
    #60037

    Good thought – I should take the time to pull a carb off one of my five 15s and see if that works – will save a lot of work on the 9.9s carb if the swap points me in another direction. The biggest nuisance in pulling a carb is putting the recoil back on, but I have found that goes much easier if I pop the flywheel first for more room to work. I have a 15 that just came back from loan to a friend that needs the recoil removed and fixed anyway….and it idles perfect for him on a week-long fishing trip. I’d like to avoid removing that lead shot if I can.
    Dave


    PugetSoundBoater
    US Member - 2 Years
    Replies: 937
    Topics: 131
    #60038

    Hi Dave, the OMC complete carb kit pn 0398453 does come with a needle bearing. I recently did 2 carbs with this OMC kit,a ’76 15 hp and a ’77 9.9. Both idle nice now. I don’t know if the Sierra kit comes with a needle bearing or not.You might as well get the OMC kit that has the bearing, cause the bearing by itself is around $11.
    I made a hooked rod out of some stiff stainless wire to remove the old bearing. Mumbles used a dental pick,which i didn’t have. Make the hook real small to get through the bearing and pull it out. It may slip out of the bearing and may take several tries to get it out.
    A way to tell if the bearing is in there is to measure the distance on the needle down to the step on the needle where the bearing fits. Then carefully measure and feel down the side into the hole with a stiff wire the same distance and see if you hit the bearing. Be careful and gentle so that you don’t gouge the surface down in there.
    It may be of some help to get the carb kit ,look at the bearing ,fit it on the needle to see what the situation is down in there, kinda visualize what you can’t see.
    When i got my ’76 9.9 i found NGK spark plugs in there.I figured the wrong plugs were in there,not being Champions or AC. I was just getting into outboards and thought how odd it was to have NGK plugs in a USA built outboard. I have had good luck with the B7HS ever since. Use B6HS if you will be trolling and idling a lot. I have not tried them yet though.
    Fleetwin has the right idea,find a good carb to swap and see if it runs better.That would help isolate the issues you have been having. I have never pried out the lead shot,never had the need to ,but i could be missing an important step. I do have a couple on hand,just in case.
    I know this may sound a bit strange, but i like the challenge(s) of my 1976 9.9, i have done quite a bit of work on it. I am confidant enough that it is going to Canada this summer as my back up to my 25 HP.
    Keep posting and letting us know how you are doing.
    Jim PSB

    "Some people want to know how a watch works, others just want to know what time it is"
    Robbie Robertson


    PugetSoundBoater
    US Member - 2 Years
    Replies: 937
    Topics: 131
    #60039

    If you look on Marine Engine and click on the photo of carb kit pn 0398453, you can see the needle bearing included in the BRP omc kit. They have it sitting on the carb to manifold gasket so you can see it on a darker background.

    "Some people want to know how a watch works, others just want to know what time it is"
    Robbie Robertson


    fleetwin
    US Member - 1 Year
    Replies: 2456
    Topics: 29
    #60048

    YES! I do see that bearing in the carb kit 398453! Don’t know if it comes with the latest part number though….
    I should order a few of those kits from ME.com
    Try that carb from your buddy’s engine first before spending the dough and time on the original carb….


    joesnuffy

    Replies: 285
    Topics: 20
    #60052

    One thing I did when pulling the recoil was kept a nut on hand that fits the bottom of the recoil bolt. I would put that nut on it while its out of engine keeps everything together not letting spring pop out. I would also use just a pull rope to start engine I was working on once it was running properly put the recoil back on as last step.

    Hope that helps,
    Joe


    outbdnut2
    US Member - 1 Year
    Replies: 1049
    Topics: 52
    #60071

    I saw that bearing in the carb kit photo but with it sitting on the gasket, I wasn’t sure if that’s what it was – Thanks for clarifying. I’ll order the kit now – as a minimum, I know I need the welch plug I pulled out, and will now pull the bearing too now that I understand what/where/how, etc. of it. Meanwhile, I’ll borrow a carb from a 15 and try it.

    A couple of you recently mentioned the NGK plugs. I’ve got BZ7HS plugs in this one already, and have tried BZ7HS-10s I borrowed form a well-idling 15. I fixed several issues on another 9.9 a couple years ago and replacing the Champions with NGK plugs was like magic making it idle perfect, so I’m a believer.

    Yes – I always put a nut on the bottom of those recoils when I pull them – learned that fast first time I pulled one!

    An observation while sticking a wire through the holes below the welch plug: When the throttle plate is all the way shut, only one of the three idle holes into the side of the carb throat is downstream of the throttle plate, so the other two are not in use. Is this enough? or is something worn on the throttle plate where at least two holes should be feeding at closed throttle plate? The center hole is almost directly under the closed throttle plate actually being partially blocked by the edge of the plate.
    Dave


    PugetSoundBoater
    US Member - 2 Years
    Replies: 937
    Topics: 131
    #60078

    I am not familiar with the B Z 7HS. i was told to use B7HS.

    "Some people want to know how a watch works, others just want to know what time it is"
    Robbie Robertson


    outbdnut2
    US Member - 1 Year
    Replies: 1049
    Topics: 52
    #60085
    quote pugetsoundboater:

    I am not familiar with the B Z 7HS. i was told to use B7HS.

    The Z means it has an "Inductive Resistor" – to block ignition noise from radios. It does the job without soaking up spark energy like a resistor does. I have these in three of my 15 HP Johnsons (1989-1991) and they work fine, great idle.

    Dave


    rudderless

    Replies: 109
    Topics: 5
    #60094

    The 74-75-76 head have issues if low speed is desirable. The later heads are lower compression, have a charge deflector to protect the plug from fuel spray. I just bought a 89 head for my 76 to improve low speed. Those heads do not have that cooling jacket around the plug like past years. I will have to mod the cowl to clear the thermostat though..

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