Page 1 of 2 12 LastLast
Results 1 to 10 of 14
  1. #1

    04 stx 900 bogging after warmed up

    Hi All, I'm fairly new to jet skis in general but have learned a ton just from this site.

    Have an ongoing issue with just one of my 04 stx 900's. I bought both of them at the same time with identical hours (roughly 110) and both with same compression numbers. 120 across the board. One of them you can't kill. You could drag it through the mud and light it on fire and it would probably still run. The other has given me nothing but problems from the time I've brought it home. Have worked through most of them but this one has me stumped. The ski will run beautifully for the first 20-25 minutes or so. You can go WOT and thrash it as much as you want for those 20-25 min. Then it'll start to bog slightly at WOT, then will gradually get worse to the point where all I can do it limp home ~20 MPH or so. I had initially thought it was a fuel delivery problem but am now leaning towards electrical. What I've done so far, even before this problem.

    Replaced spark plugs
    Replaced battery (the one it came with was nearly dead)
    Replaced exhaust expansion chamber (hole had developed in the bottom probably from lack of maintenance)
    Cleared all the cooling channels, including stator. The previous owner had gotten sand in there and it was overheating in the beginning (overheat warning on dash)
    Checked fuel system - tank, lines, filter, pump - no restrictions.
    Checked fuel tank vent - working properly.

    I have opened the CDI box but it looks very clean and dry in there. Connections look good.

    Any ideas on where to start?

    Stator
    Coil
    CDI
    Voltage regulator
    ???

    Thanks for any and all ideas.

    Chris

  2. #2
    steve45's Avatar
    Join Date
    Feb 2008
    Location
    Texas
    Posts
    7,835
    +1
    785
    Welcome aboard, Chris!

    Could be an exhaust leak filling the hull with fumes. Ride it with the seat off and see if it still happens, or if you see smoke inside the hull.

    You said the fuel vent was OK, but I'd try loosening the gas cap for a few seconds the next time it happens and see if that helps. There is a check valve that lets air in, but prevents fuel from coming out. Make sure that is installed correctly.

  3. #3
    Quote Originally Posted by steve45 View Post
    Welcome aboard, Chris!

    Could be an exhaust leak filling the hull with fumes. Ride it with the seat off and see if it still happens, or if you see smoke inside the hull.

    You said the fuel vent was OK, but I'd try loosening the gas cap for a few seconds the next time it happens and see if that helps. There is a check valve that lets air in, but prevents fuel from coming out. Make sure that is installed correctly.
    Thanks Steve.

    I'll try both. I did lift the seat as soon as I limped back to the dock and nothing unusual. No smoke or excessive smells. Very little water in there too so I don't think it was that being sprayed into the intake.

    I haven't tried to loosen the cap but I did test the check valve and it seems to be working the way it should.

    It's obviously heat related but would anything electrical cause the symptoms I'm experiencing?

  4. #4

    Join Date
    Mar 2010
    Location
    Long Island, NY
    Posts
    962
    +1
    89
    Remove the boots from the spark plug wires. Trim the wires back about a half inch. Then re-install the boots.

  5. #5
    steve45's Avatar
    Join Date
    Feb 2008
    Location
    Texas
    Posts
    7,835
    +1
    785
    There is a cooling passage on the front cover, under the oil pump. I'm not sure what it does. It may cool the bearings for the oil pump drive, or it may cool the stator. Anyway, they get clogged up with debris. Try blowing into one of the hoses on the front cover and see if it's clogged. If so, pull it and clean it.

  6. #6
    That cooling passage is on the top of the oil pump and I took that off yesterday and blew through it. Water was bubbling out so I assume that's good.

    @grumpy_steven. Thanks. I've seen that suggestion before but it's the whole engine falling flat on its face and not just one or 2 cylinders.

    I'm going to take it out again today and test a couple things mentioned here and report back. Might even swap CDI, voltage reg with the other one just for the hell of it.

  7. #7
    steve45's Avatar
    Join Date
    Feb 2008
    Location
    Texas
    Posts
    7,835
    +1
    785
    When it starts running badly, try pulling the choke out halfway and see what happens.

  8. #8
    Ok so i didn't try that yet but I loosened the cap and switched to res and no change. I guess I really shouldn't even say it's a bog. A bog to me implies that it has lost its normal power or running rough. Mine is falling flat on it's face and cutting out completely at a diminishing max rpm...to the point where only idle is stable. so 20 min>>fine. 20-21 min>>cutting out at WOT. then quickly and gradually decreasing to just trolling speed. I'm slowly letting go of the throttle as it keeps cutting out all the way down to idle. hope that makes sense.

  9. #9
    Ok, just to circle back on this. I ran the ski with the seat off and when the problem eventually surfaced there was no smoke in the hull or anything indicating an exhaust or water leak. I unscrewed the gas cap and no change. I pulled the choke and no change, other than it ran even worse. I tested the voltage regulator when I brought it back to the dock and it was reading 13.65 so that's good. The only other pieces I can think of are the stator or the CDI.

    Thoughts?


  10. #10
    steve45's Avatar
    Join Date
    Feb 2008
    Location
    Texas
    Posts
    7,835
    +1
    785
    Yes, perhaps the stator is acting up when warm. Since you've got two of them, try swapping them. Yea, I know, it's a pain. But it's better than finding that you bought a new one and it's not the problem.

Page 1 of 2 12 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Back to 98 STX 1100 and now 2001 STX 900 cooling quetion?
    By jeeps2creep in forum Kawasaki How To & FAQs
    Replies: 3
    Last Post: 09-21-2016, 10:53 AM
  2. HELP: zxi 1100 and 900 stx low speed bogging issue
    By grahams in forum Kawasaki PWC Performance (2-stroke)
    Replies: 12
    Last Post: 03-23-2013, 10:36 PM
  3. Bogging down once warmed up good... but cause is not the VR?
    By DKFox in forum 2-Stroke Performance
    Replies: 17
    Last Post: 06-08-2011, 01:21 PM
  4. Front latch clip STX 900 & ZXI 900
    By Lineman482 in forum Kawasaki How To & FAQs
    Replies: 0
    Last Post: 07-26-2009, 04:23 PM
  5. Kawasaki STX 900 & ZXI 900 on double trailer
    By Lineman482 in forum Kawasaki Classifieds
    Replies: 0
    Last Post: 08-11-2008, 06:59 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •