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  1. #1
    skiversinc's Avatar
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    Question Losing revs on WOT

    You'll all, no doubt, be aware of the long running saga of my 2001 Virage TX. It's had new stator, CDi, pump,long pump bolts, carb rebuilds etc........
    I've finally solved the non sparking problem & technically, she should be ready to go.
    I took her out the other weekend & had lack of power. Found the problem was the connection from the water box to the resonator. The hose clamp had been over tightened & had crushed the opening on the resonator, creating a crease & water leak.
    I took a heat gun to the resonator & have reshaped it. Refitted & thought all would be right with the world again - WRONG!
    She started great, ticked over fine, did 5 knots all the way out into the channel and then I opened the throttle. She ran great for a few seconds & then lost top end power. Was running at around 5000 revs. I wasn't going to take chances so I came back in straight away.
    Inside the hull was fine - no leaks (one good point) but I can't work out why she would bog like that after a few seconds of WOT.
    Would the new CDI need the timing looking at? just wondered if this might cause the above problem?

    Anyone got any ideas of the cause of this issue 'cos I'm stuck!!


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Any warning message on the display?

    Did you check the engine temperatures with your hand?

    When it lost power, did squeezing the throttle wide open make any difference?

    You may need to do some testing while strapped to the trailer and backed down the launch ramp. You can apply throttle while on the trailer, just make sure the bow is strapped down securely and there is no debris on the ramp that could get sucked into the jet pump intake.

  3. #3
    skiversinc's Avatar
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    Thanks for the reply,

    No messages on the display, just loss of power. At the time it lost power, I had WOT, however, I did try feathering it to see if that made any difference but it didn't.
    The engine was warm but not hot.

    I'm after replacing the temperature sensor to be on the safe side.

    Seeing as the carbs have been rebuilt - new gaskets and jets cleaned, would I need to reset the carbs? I wouldn't have thought so as they'd be set for operation previously.

    I just wondered about the ignition curve. Would the timing need to be adjusted? The new stator & CDI have been fitted but would the timing be set to stock on these?

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    What maximum RPM were you seeing after the power loss began?

    Ignition timing should not be a problem, in that if you had full power for several seconds then the timing was there.

    Temp sensor - unless there was a wiring problem, the MFI display should have warned if the temp sensor was triggering a HOT condition. If you open the electrical box and ground the Tan wire that runs to the temp sensor (short Tan terminal to Black terminal) the MFI display should instantly show HOT. Engine might need to be started for the MFI to respond to HOT signal).

    Check cylinder compression. Let's make sure the engine internals are OK.

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