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  1. #1

    '92 Sea Doo XP 580 backfiring?

    Picked up a 92 580. Had a messed up carb - throttle shaft was literally bent, and electronics box needed replaced. Swapped carbs from a 650, put a used box in it, and got it running. Made it maybe 15 minutes on the water, and it sputtered and died, refusing to start again. Was backfiring and popping out the exhaust as well as the carb. I recharged battery, put new plugs in it, checked to make sure fuel was not contaminated, and tried to start it again. Still pops and backfires, refuses to start. Where should I start looking? I did notice one of the two banjo bolts on the oil pump had worked itself slighty loose, and the line did not have oil in it once it had been sitting for some time. The engine seems to have very good compression.


  2. #2
    timing is off

  3. #3
    How would the timing have suddenly gone awry?

  4. #4
    wkuadam07's Avatar
    Join Date
    Feb 2013
    Bowling Green, KY
    Have you unhooked the rectifier to see if that makes any change? Also check spark on BOTH cylinders and see if you have good strong spark... go from there... next thing to check is rotary valve timing, it could have been wrong all along, or stripped a rotary valve gear.

  5. #5
    Timing can go off by the rotary valve slipping on the brass gear that drives it or the flywheel can shear the key on the shaft and move. My experience is popping and backfire = fuel and spark just at the wrong time.

  6. #6
    Rectifier - red/black wire that is split at coil? If so, yes, and no difference. I pulled carb and oil pump/rotary valve housing, shaft wasnt snapped or really loose as far as I can tell. Checking flywheel next... Its backfiring out the carbs BAD. Like, shoots flames.

  7. #7
    Okay you actually have to check the timing of the rotary valve with the cover off. Mag piston has to be at tdc and you have to look up where the valve is supposed to be for that engine.

  8. #8
    It ran perfectly before - why would it stop? I will check it again.

  9. #9
    It would stop because its 24 years old, and sounds like its seen its share of abuse/neglect. Gears, bearings and other parts get worn down over time etc. and a million things could have happened. Don't worry about it just look into those couple things and verify that rotary valve is in the right spot and that it turns when you spin the engine by hand. Let us know what you find.

  10. #10
    I understand that - the question is why it would run and then stop if the timing was off enough for it to not run the whole time.

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