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Ultranautics Jetstar - Starting problems

Discussion in 'Classic Jet Boats' started by Matty_Ice, Apr 8, 2018.

  1. Matty_Ice

    Matty_Ice New Member

    Messages:
    3
    Ratings:
    +0 / 0
    Boat Make:
    Other
    Year:
    1995
    Boat Model:
    Limited
    Boat Length:
    Other
    I just picked up a 1991 Ultranautics Jetstar that has a 60hp 800cc 2 stroke engine. The boat is very clean and it pretty good condition. After a new battery, I was able to start it up twice using new fuel in the tank and a little starting fluid (Only a little half second spray, the starting fluid has lubrication as well) As of now, after new plugs, I cannot get the engine started. I have 120/120 compression in both cylinders which sounds normal (anywhere from 120-130). Spark is strong in both cylinders, I arched the plugs and used a spark light tester. Spark+Compression+ Fuel/Air = running engine. I'm kinda stumped as of right now, anybody that can point me in the right direction would be awesome.

    This little boat is really cool, I'd like to get it running for this upcoming summer!
     
  2. bronze_10

    bronze_10 Jetboaters Captain

    Messages:
    2,838
    Location:
    Raleigh / Wake Forest Area..
    Ratings:
    +2,483 / 24
    Boat Make:
    Yamaha
    Year:
    2008
    Boat Model:
    SX
    Boat Length:
    23
    I have no idea how to help you bust it sounds like a cool boat... We would love to see some pics.
     
  3. zipper

    zipper Jetboaters Lieutenant

    Messages:
    970
    Location:
    Milton, Vermont Lake Champlain
    Ratings:
    +1,072 / 13
    Boat Make:
    Yamaha
    Year:
    2007
    Boat Model:
    AR
    Boat Length:
    23
    Welcome to the forum. Not too many of us here have even heard of that boat before, well at least not me anyway. I found this thread on this site. https://jetboaters.net/threads/ultra-nautics-jet-star-1250.10329/ . After reading your checklist above, what comes to my mind is the gas/oil mix. Is it a pre-mix or is there a oil reservoir. I have heard some of the early Yamahas had issues with this. Don't know I am guessing here if you have good spark and compression there is not much else to consider. Good luck.
     
    Last edited: Apr 9, 2018
  4. Matty_Ice

    Matty_Ice New Member

    Messages:
    3
    Ratings:
    +0 / 0
    Boat Make:
    Other
    Year:
    1995
    Boat Model:
    Limited
    Boat Length:
    Other
    The oil is premix 50:1, put brand new gas. I'm starting to think maybe its the CDI and the engine timing is off. Maybe the Woodruff key? Not sure.
     

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  5. Beachbummer

    Beachbummer Jet Boat Addict

    Messages:
    601
    Location:
    Houston TX
    Ratings:
    +348 / 6
    Boat Make:
    Yamaha
    Year:
    2008
    Boat Model:
    SX
    Boat Length:
    23
    With using starting fluid, even if timing was off, it should at least back fire, or show some kind of life.

    No fire at all has to be no fuel, no spark, no air, or no compression, right?

    I'm stumped with you... Any chance cables are loose and spark is not there when plugs are in the right place?

    Best of luck
     
  6. bronze_10

    bronze_10 Jetboaters Captain

    Messages:
    2,838
    Location:
    Raleigh / Wake Forest Area..
    Ratings:
    +2,483 / 24
    Boat Make:
    Yamaha
    Year:
    2008
    Boat Model:
    SX
    Boat Length:
    23
    He said it started with the spray... That tells me it has to be fuel delivery.. Have you rebuilt the carbs. I know my old two stroke ski always needed the carbs rebuilt in the spring. I thank the gas that is in the carbs evaporates over the winter but the oil does not clogging the carbs. But there are more knowledge people here that can speak to that.
     
  7. Matty_Ice

    Matty_Ice New Member

    Messages:
    3
    Ratings:
    +0 / 0
    Boat Make:
    Other
    Year:
    1995
    Boat Model:
    Limited
    Boat Length:
    Other
    I have not rebuilt the carbs yet, but even with the starting fluid, it should at least fire and then sputter out (telling that there is a delivery issue) I even put a little gas in the top cylinder and I got nothing. The fuel pump seems to be sucking fuel too, I can see the fuel flowing through the clear plastic inline fuel filter. I guess I can take apart the fuel pump and see if there is a rip somewhere.
    Something is tell me that maybe not enough air is getting to the cylinders? That can be an option. The new plugs I took out had a little bit of fuel on them, not soaked but you could see the gas.
     
  8. bronze_10

    bronze_10 Jetboaters Captain

    Messages:
    2,838
    Location:
    Raleigh / Wake Forest Area..
    Ratings:
    +2,483 / 24
    Boat Make:
    Yamaha
    Year:
    2008
    Boat Model:
    SX
    Boat Length:
    23
    :bookworm: hummm..
     

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