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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

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    Year:
    1995
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    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 Admiral

    Messages:
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    Year:
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    SX
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    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 Captain

    Messages:
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    Location:
    Milton, Vermont Lake Champlain
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    Yamaha
    Year:
    2007
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    AR
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    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

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    1995
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    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 Junkie

    Messages:
    1,068
    Location:
    Houston TX
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    Boat Make:
    Yamaha
    Year:
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    Boat Model:
    SX
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    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 Admiral

    Messages:
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    Location:
    Raleigh / Wake Forest Area..
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    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

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    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 Admiral

    Messages:
    3,870
    Location:
    Raleigh / Wake Forest Area..
    Ratings:
    +3,709 / 69
    Boat Make:
    Yamaha
    Year:
    2008
    Boat Model:
    SX
    Boat Length:
    23
    :bookworm: hummm..
     
  9. Kurt Kolby

    Kurt Kolby New Member

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    I have a 1990 jetstar .. same pr
    are you sure the premix is 50:1? Just bought a jetstar and was not sure. Where did you get your info on premix... thanks
     
  10. 21Waterfun12

    21Waterfun12 New Member

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    I just an '89 jet star, been struggling for 2 months with same isssue, pull carbs and clean everything. I had pulled and half cleaned about a month ago, redid last night, my problem was gunk blocking the holes in the brass part in the center of the carb, pull the bowls off, remove jet from center of float, then remove 10mm nut jet mounted into... clean that and I'll put money that and i'll bet it'll work.

    My issue is just after getting it running, when rev'd there are sparks shooting from starter area... any thoughts before I just pull it? I'm confused why the starter would have any electricity to it after the engine fires, and I'm no longer cranking... thoughts?
     
  11. jdonigancpa

    jdonigancpa New Member

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    Location:
    Lake Lotawana, MO
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    I have owned a 1991 JetStar for a little over 2 years now. First note I will add is that the owners manual came with mine, and it referenced a 40:1 fuel mix. Not to say that this is your issue, but just a side note. Not sure if that was different for any other year. The issue I have constantly had is that when I finally did get it to start, it would bog down continually. Definitely fuel starved. Fast forward to today, it is in the shop getting the tank pulled so it can be inspected and cleaned out. Also, the fuel intake line is going to be replaced. Our method on figuring this as an issue was that we pushed air from the fuel bulb back to the tank. It acted like there was some blockage. Afterwards it ran great, but only a little while before repeating this issue. My advice from my experience is that based on the age of these boats, the tank needs to be pulled and cleaned, carbs rebuilt (AND BALANCED) and intake/delivery lines replaced. Basically replace your fuel system (best off if you can get by with existing fuel pump since they are out of production). I wish I did it day 1, as I would have been able to enjoy this boat a whole lot more than I have so far.
     
  12. hrpuffinstuff

    hrpuffinstuff New Member

    Messages:
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    +0 / 0
    Boat Make:
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    Year:
    1995
    Boat Model:
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    Other
    I.have.owned.a.jetstar.since.new(1991).One.thing.you.might.want.to.look.at.is.the.fuel.pickup.line.mine"melted".off.of.the.fuel.tank
     
  13. hrpuffinstuff

    hrpuffinstuff New Member

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    Year:
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    Also.the.owners/parts.manual.I.have...it.is.50/1mix
     
  14. Matty_Ice

    Matty_Ice New Member

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    Sounds like the fuel starvation is definitely an issue on these boats. My boat seems to have been running fine now. After I went through about 10 gallons of gas its running good.
    When my engine started to bog out, I pushed the key in, which automatically chokes the carb. The boat immediately "unbogged" itself. Making me think it was in fact starving.
    I think my culprit was bad gas, I'm running Klotz 50:1 and having no issues of fuel starvation as of this past labor day weekend.

    My boat has been having issues starting. My new fully charged battery was getting no response from ignition or any switch (bilge, stereo aka). I jiggled the negative battery terminal clamp and noticed little blue sparks. Then I had full power.
    Obviously this sounds like a bad connection, but my terminal clamp is very tight. Would I just need some waterproof lithium grease?
     
  15. CapnDan

    CapnDan New Member

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    Dirty fuel tanks and lines are usually the fuel starvation problem. Some ideas that help. Add a small fuel pump by the gas tank wired to the key switch. Drain your fuel via the fuel pump or siphon it out. Add two gallons of denatured alcohol from a hardware store to the tank and let it sit for a hour. Add a fuel filter back by the engines fuel inlet line. Disconnect the fuel line and stick it in a separate container. Turn the key switch on and let the new fuel pump run the alcohol through the whole system. More than likely your fuel filter will slowly fill with gunk. My boat has the 90 hp and was always looking for more fuel. The fuel pump and fuel filter solved the problem.
    Other common problems
    cracked magnet under the fly wheel
    bad coils
    bad CDI box
    bad diaphram on the engine fuel pump
    All these parts are available on ebay. Manuals and parts diagrams can be found on line
     

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