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  1. #1

    98 seadoo 787 bogging down

    I have recently purchased a seadoo, put a rebuilt engine in it 787, It goes ok problem im having is when i take off, once warm it will plane then sit on 4700rpm and not go any higher, maybe 30mph, it will not go higher untill i go over a wave and the prop lifts from the water, free spins and then it will rev up to 7000 or so and go 50+ mph goes killer once it get going, but if its calm water its impossible to get going.
    The engine is 2 hours old so i know thats ok, have cleaned out carbies, and the filters in them, cleaned out the fuel water seperator, routed around from fuel switch. still the same,
    I am running extra oil in the fuel maybe 80:1 dont see how that can do it,
    I have read removing the rectifyer 15amp fuse car remove the rpm limiter, but there was 2 15amp fuses so dont couldnt do that, It seems that the 12volt low always shows to even tho its a new battery.
    It seems like once it free spints its draging more vacume, but i cant see how that would happen with these carbs as there is no secondary stage as such.
    Or is that what the pop valves doo?
    any suggestions would be a help.


  2. #2

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    unplug the red wire for the rectifier and enjoy the new power-- Merry Christmas...

  3. #3
    Really stupid question, is the rectifyer the copper coil that based onto the flywheel housing, and if i disconnect it and it fixes the problem i asume i need a new rectifyer, a bit more of a clear disription on how to disconnect the rectifyer would be apprecated at them moment im no better off as i dont know how to "disconnect the red cable from the rectifyer"

  4. #4

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    The rectifier is in the front grey box that is to the left of the gas tank. It has a bunch of wires coming out of the front and rear of it. Inside the box you will find the rectifier-- it looks like this:

    http://www.ebay.com/itm/seadoo-1996-...item58911118d1

    Disconnect the red wire. Yes, if disconnecting the red wire makes your ski run correctly, your's is bad and you need a new 1. When your red wire is disconnected your charging system is disabled, so make sure you have a good battery installed so you will not get stranded.

  5. #5
    Quote Originally Posted by jim View Post
    The rectifier is in the front grey box that is to the left of the gas tank. It has a bunch of wires coming out of the front and rear of it. Inside the box you will find the rectifier-- it looks like this:

    http://www.ebay.com/itm/seadoo-1996-...item58911118d1

    Disconnect the red wire. Yes, if disconnecting the red wire makes your ski run correctly, your's is bad and you need a new 1. When your red wire is disconnected your charging system is disabled, so make sure you have a good battery installed so you will not get stranded.
    +1 Had the same issue a few years ago turned out to be the rectifyer died.

  6. #6
    ok had the ski on the water for a week, didnt fix it self, I tryed cutting the red cable on the rectifyer and no different still drove exactly the same, a couple of times i was able to flick the throttle enough to get it to take off but still the same no go untill if jumps out of the water.
    Im not worried about the 12volt low coming up, its the driveabilaty i need to fix its impossible to ride on flat water.
    I spoke to a motor bike wrecker and he suggested that the coil may be no good and its not chaninging from the primary to the secondary properly.
    Im not all that keen on buying bits and peices if they are not going to fix the problem I really want to have a shore thing before i hand over the cash.

  7. #7
    flyin' the friendly skies airbornexp's Avatar
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    sounds like its time to pull the carbs...there are little screens in the carbs that tend to gunk up. does it still have gray tempo fuel lines? if so those need to be changed too. Follow the DIY fuel system cleaning thread at the top of this section.

  8. #8
    I have already removed carbs and cleaned them out, one filter was blocked and the other partually, cleaned out all the rest and have cleaned out the fuel system. im fairly confident thats its not the carb/fuel systems. As it ran the same before and after the clean out, and it runs fine once its had a little free spin, if it was a fuel issue i would imagine it would run like a pig all of the time.

  9. #9
    flyin' the friendly skies airbornexp's Avatar
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    I would say that you need to check the carb settings and where your screws are at. there is a sticky at the top of this section for that too. you may want to check the main ground as they have a tendency to corrode since the ski is 12 years old. if thats not it then I would think that you need to find a friend with a good mpem for your motor and see if that makes a difference.

  10. #10
    Man of God brittrich's Avatar
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    To answer one of your questions, the pop off valve/pressure problems usually manifests itself as lean hesitation when getting on the throttle from idle. In particular if you've installed a less restrictive air filter and/or removed the stock flame arrestor, manifold pressure decreases. In this instance, you would need to adjust pop off to regain crisp throttle response.

    I would have pop pressure checked to see where you are with that. Running good after jumping a wave removes load which "could" result in what you're describing even with incorrect pressure settings.

    Give us an update

    My 2 cents....

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