First attempted start of JS550
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  1. #1
    PWCToday Newbie Stovebolt's Avatar
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    First attempted start of JS550

    I finally completed my rebuild of the '88 JS 550. I installed new pulser and exciter coils during the build, bought from ebay. I read the warnings about these possibly being wired backwards but wired them normally and kept my fingers crossed.

    So, everything is back in the ski; I checked that I have spark on both cylinders (but have new sparks on order), poured a little fuel/oil mixture into the carb, sprayed a little starter fluid into the carb, and hit the start button. The engine is spinning but not even sputtering.

    How do I tell if the sparks are firing 90 degrees off? There is no fuel in the ski other than what I poured into the carb. Do I need to prime the fuel system at all?

  2. #2
    PWCToday.com Is My Home Away From Home
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    Re: First attempted start of JS550

    timing light and yes, prime fuel system.

  3. #3
    PWCToday.com Is My Home Away From Home wmazz's Avatar
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    Re: First attempted start of JS550

    Quote Originally Posted by Stovebolt View Post
    I checked that I have spark on both cylinders (but have new sparks on order)
    (1) poured a little fuel/oil mixture into the carb
    (2) sprayed a little starter fluid into the carb
    (3) hit the start button.
    (4) The engine is spinning
    BOOM!

    Great way to create a huge backfire with the
    potential of the waterbox exploding!


    Please be careful, and try not to use starting fluid.




    Quote Originally Posted by Stovebolt View Post
    How do I tell if the sparks are firing 90 degrees off?
    I have never had that happen before? The system is supposed
    to fire every 180 degrees on both spark plugs, at the same time.
    So both plug wires need to be connected and with a good ground
    to spark.

    (No Need to Gas it Up if you are testing the spark)

    Take the splash guard off of the driveline bearing housing, and
    mark the driveline coupler with a sharpie at front cylinder tdc.

    With both in place and plug wires connected use the timing light
    to check for the timing mark close to tdc. That should be good
    enough for now.




    Quote Originally Posted by Stovebolt View Post
    Do I need to prime the fuel system at all?
    I used to just remove the return line from the rev limiter and
    blow into the hose. When it is primed, a small amount of fuel
    will squirt out the return line restrictor.


    But if everything is correct it should start without a prime
    in 1 minute or less.



    Bill M.
    Last edited by wmazz; 07-18-2021 at 09:06 PM.
    Horsepower == Speed, RPM != Speed



  4. #4
    PWCToday Newbie Stovebolt's Avatar
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    Re: First attempted start of JS550

    Thanks for the tips. I got the timing light out and it's firing correctly. I even got it to sputter a little. I guess I shouldn't have thought too much into it from reading the previous post about bad coils. Now I need to prime the fuel to get it to run.

  5. #5
    PWCToday Newbie Stovebolt's Avatar
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    Re: First attempted start of JS550

    I'm back looking for more advice to get this ski running.

    I went through the ski again today, put fuel in the filter housing and put all the fuel lines back together. First attempt and it nearly started, stumbled a bit and died. OK. I'm almost there. Several more attempts resulted in just frustration. I pulled the spark plugs. They are dry, clean and brand new. Checked the gaps and that is good. I put a vacuum gauge on the fuel pump and that is pulling vacuum. Put the vacuum pump on the line before the carb and it pulls fuel through the system. But somewhere between the fuel pump and the carb, there is a breakdown. I put a splash of fuel in the carb and the motor jumps to life.

    Low speed screw is set at 1-1/4 turns, high speed is set at 1 turn and pilot is set at 1 turn. By turn the pilot out, does that make it more rich?

    Thanks for any help to get this thing on the water. I could take a video but I think you've all seen/heard a starter spin with no results.

  6. #6
    Top Dog FOG's Avatar
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    Re: First attempted start of JS550

    Here are the settings from the manual. I have Pilot penciled in as 1 5/16. My old RB-carbed 440's and 550's were sometimes hard to start. It may take several prime/start sequences before it fires and stays running. Good Luck! It sounds like you're almost there...

    kawicarbs.jpg
    I'll quit before I sit~~~

  7. #7
    PWCToday.com Is My Home Away From Home wmazz's Avatar
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    Re: First attempted start of JS550

    Quote Originally Posted by Stovebolt View Post
    First attempt and it nearly started, stumbled a bit and died. OK. I'm almost there.
    Several more attempts resulted in just frustration. I pulled the spark plugs. They are dry,

    clean and brand new.

    I put a splash of fuel in the carb and the motor jumps to life.
    It is very possible the needle and seat isn't opening. Or it opens
    and quickly closes again.

    Test that idea by removing the flame arrestor (Is there a choke)
    If yes, full choke and no throttle until it momentarily kicks over.
    Then 1/8th throttle and full choke, and it should start. If it doesn't
    it is just a typical 550, and time to do some more trouble shooting.

    If there is no choke, remove the flame arrestor completely (but if
    your carb has a K&N adapter, leave the adapter on). Next cover the
    top of the carb with your hand and crank it over, fully choked, no
    throttle, and if the needle and seat opens, you feel gasoline on your
    hand. If it doesn't it is just a typical 550, and time to do some more
    trouble shooting.

    But if it did wet your hand give it 1/8 throttle, and try to start.


    On a typical 86' thru 90' 550 pp, there are many reasons why they
    don't like to start and if they are not all repaired, they can be very
    difficult to start if you don't know the secret hand shake.

    Often it is a dance where it isn't getting any gas. So you prime it,
    and next thing you know it is acting like it was flooded.


    BIll M.
    Horsepower == Speed, RPM != Speed



  8. #8
    PWCToday Newbie Stovebolt's Avatar
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    Re: First attempted start of JS550

    Thanks for the tips. I have spent a good portion of the morning in the garage with no luck. I have a choke but no cable. Closed that and held the start for several seconds. Still nothing. Not even the slightest stumble like its trying to start. I pulled the carb off and took the fuel pump apart. Fuel is getting thru a portion of the pump but not all the way to the pilot or low pressure ports.

    Would a primer plunger help? What are the other options for carbs? Having rebuilt this entire ski, this is enfuriating that I can't get it to start.

  9. #9
    PWCToday.com Is My Home Away From Home wmazz's Avatar
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    Re: First attempted start of JS550

    The pilot screw starts the engine, did you open it about 1/2 turn or more
    like FOG suggested.


    Quote Originally Posted by Stovebolt View Post
    I pulled the carb off and took the fuel pump apart.

    Fuel is getting thru a portion of the pump but,

    not all the way to the pilot or low pressure ports.
    Did you gather any carb related info from the GroupK web site? GroupK
    is filled with bad info. For example: "Pop off pressure – This term refers
    to the amount of fuel pressure needed to push the float needle valve
    away from it’s sealing seat."

    But that is not what pop-off pressure is, or how the needle and seat opens.
    Because people do not understand how a jet ski carb works, they often blame
    the fuel pump for everything from starting to detonation.

    The needle and seat can fail to open from something as minor as a vacuum
    leak on the carburetor base gaskets, or a stiff float diaphragm.

    Unfortunately 86' and up piston port (PP) 550's have more baked in problems
    than other ski's. But it is also possible that some of the problems have been
    addressed by a previous owner.

    It is possible that the float diaphragm is stiff, or there is a hole in the center
    of the float diaphragm, and a few other problems inside the carb. If you are
    lucky, some minor work may fix the problem.


    Bill M.

    You mentioned a rebuild, but you were referring to the stator? How well did
    it start and run before the stator failed and how much time (or years) did the
    repair take?
    Last edited by wmazz; 08-08-2021 at 02:38 PM.
    Horsepower == Speed, RPM != Speed



  10. #10
    PWCToday Newbie Stovebolt's Avatar
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    Re: First attempted start of JS550

    Thanks, Bill.

    Rebuild = I bought this ski as a non-running project with a hole in the hull. I've never heard it run but I have rebuilt everything under the hood, literally. The coils were just a portion of that but this thread started asking about those firing 90 degrees off as I read in another post. But that's working fine.

    The carb is completely rebuilt with a new diaphram and gaskets. I'm going to buy some new fuel lines and run directly from the tank to the carb with a small filter. Then I should be able to tell if fuel is getting to the carb. But that's going to have to wait until next weekend.

    As for GroupK, I have not found that forum but from your description, I think I'm better off not finding it. I'll just stick with my head scratching and reading the manual.

    Cheers.

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