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  1. #1

    1995 SLX lost high end power overnight

    Hello everyone, this is my first post. I've been doing some reading and have tried a few things to solve this problem but no luck yet. So here's the jist:

    1995 SLX with the 780 Fuji. I recently got this jetski and I ended up taking it to a mechanic for what I thought was low end carb issues. Turns out there were two missing Reed valves. Good stuff previous owner.

    He serviced them and installed two used ones he had at his shop, I water tested next day, ran AMAZING. I ran it for one hour on one day, 45 minutes the next, ran PERFECT. Tried the following day (3rd day in a row), and all my high rpms were gone. It revs crisp and sharp till about 4000-4200 rpms,then sounds boggy and what I'd imagine a limp mode would sound like (more rich on fuel). My display works and is displaying no errors, good gas and oil levels. So here's what I've done so far to troubleshoot:

    Compression test- all 3 cylinders good and within 10psi of each other

    Disconnected gray wire in box- made no changes

    Took tops off carbs- no excess fuel spitting from the top

    Final and most telling test- ran engine on one cylinder at a time. It will run on MAG and CEN but will not run on PTO.


    That being said, could it have broken another Reed (he just added a used Reed to the PTO cylinder)?

    Thanks all in advance, I love good forums.


  2. #2
    Click avatar for tech links/info K447's Avatar
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    Welcome.

    Check cylinder compression on each cylinder. Throttle held wide open, all spark plugs out.

    Also, click here
    http://polarispwcknowledge.shorturl....t-things-to-do

  3. #3
    I will try this tomorrow. I've never done a compression test while holding throttle open. I'll have to lookup what that can mean. *edit* I Googled it, I had no idea. Thank you!

    And I've been scouring that link you sent for almost a week. I can't seem to figure it out because I don't believe it's in "limp mode" based on pulling the gray wire.

  4. #4
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Welcome to the Hulk.

    After running the engine for a bit, put your hand on the PTO cylinder (or all 3 for that matter) does it feel cooler than the other 2? That's a generic way of knowing if that cylinder is actually firing.

    You can also install an in-line spark tester to see if you're getting spark.

    What are your sparkplugs telling you? How do they look? Maybe you fouled a plug

    Do you have the correct spark plugs installed and gapped properly? NGK BPR8ES gapped at .028"

    What does your piston wash look like? That can tell you if you're running rich, lean, or if there's water getting into the combustion chamber.

    Let us know what you fing.

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  6. #5
    Hello again,


    So after the advice given I ran another compression test with all plugs out and WOT. Here's the results:


    MAG - 150 PSI
    CEN - 150 PSI
    PTO - 130 PSI


    I also ran the engine on a trailer for about 30 seconds and got even more baffled. Here's the results :


    MAG - cool to touch
    CEN - burned my fingers
    PTO - cool to touch


    After that I decided to do another one cylinder at a time test and got even more confused. Here's the results:


    MAG only - instant dead
    CEN only - remained running
    PTO only - instant dead


    So after that I decided to check plugs again, plugs are correct type, MAG and CEN were gapped correctly, PTO was around .24 so I corrected that and reinstalled. Retested one cylinder at a time, still instant dead.


    At that point I decided to remove the heads and take a few pics of the piston wash, MAG and CEN seemed about the same, PTO is wet as hell inside as shown in pics. That being said, maybe an ignition problem? I know the 20psi difference is pointing at something bad in that cylinder, should I automatically assume it needs a rebuild? The jetski life is new to me but I'm mechanically inclined enough to work on these things. Any help is appreciated, thank you.
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  7. #6
    sdlvx's Avatar
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    Did you check each cylinder for spark? You can remove the spark plugs, ground them on some bare metal (like a head bolt clear of the spark plug hole), crank it with the lanyard in and see if there is any spark. I think it's pretty weird for only one cylinder to lose spark, so it may be something like a bad spark plug, spark plug cap on wrong, broken spark plug wire, something else. Check for spark on rear cylinder. Check for fuel too. If it has compression it has to be either lack of spark or lack of fuel.

    EDIT: missed your last post

    The fact the PTO plug is covered in fuel means no spark. Double check spark. This is for a chainsaw but it's the same thing

  8. #7
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Thanks for posting the pics.

    Hard to make out the PTO, but are the cylinder walls rusted?

    The CEN has almost 0 wash. And what I do see looks rust colored.

    The MAG looks like it may be developing wash or washing it clean with too much fuel.

    It doesn't really make sense, that removing the CEN cylinder plug wire it would still run. That would say that it's not firing when removing the other 2 kills it immediately. When it look like the PTO is the one not firing.

    How do the spark plugs look? Are they oil fouled? Dry and white in color? Dry and black in color?

    Were the carbs ever addressed? Verify jetting and that they are all clear? Carbs are in sync? Both the CEN and PTO are showing they need a lot more fuel or you risk holing a piston.

    Any signs of fuel spitting out the tops of the carbs when running? Indicating broken reeds.

    How's the condition of the elec box inside? Any signs of water or corrosion?

  9. #8
    Quote Originally Posted by sdlvx View Post
    Did you check each cylinder for spark? You can remove the spark plugs, ground them on some bare metal (like a head bolt clear of the spark plug hole), crank it with the lanyard in and see if there is any spark. I think it's pretty weird for only one cylinder to lose spark, so it may be something like a bad spark plug, spark plug cap on wrong, broken spark plug wire, something else. Check for spark on rear cylinder. Check for fuel too. If it has compression it has to be either lack of spark or lack of fuel.

    EDIT: missed your last post

    The fact the PTO plug is covered in fuel means no spark. Double check spark. This is for a chainsaw but it's the same thing
    The spark seems to be intermittent on this thing. If I mess with the caps(cut the wire back a 1/4 inch and reinstall the cap) it seems to make the spark constant and strong but after a couple tests of grounding the plug it goes back to being intermittent and weak. Maybe it's a simple fix by installing new wires? My plugs are all brand new.

  10. #9
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by Stealthjm83 View Post
    The spark seems to be intermittent on this thing. If I mess with the caps (cut the wire back a 1/4 inch and reinstall the cap) it seems to make the spark constant and strong but after a couple tests of grounding the plug it goes back to being intermittent and weak. ...
    I suspect something other than the spark plug wires is changing as you repeat your crank tests. Battery voltage declining, CDI warming up internally, resistive ground connection self-heating, something.

  11. #10
    See your quote for replies. Thanks!

    Quote Originally Posted by xlint89 View Post
    Thanks for posting the pics.

    Hard to make out the PTO, but are the cylinder walls rusted? I'll have to check today and get back to you.

    The CEN has almost 0 wash. And what I do see looks rust colored.

    The MAG looks like it may be developing wash or washing it clean with too much fuel.

    It doesn't really make sense, that removing the CEN cylinder plug wire it would still run. That would say that it's not firing when removing the other 2 kills it immediately. When it look like the PTO is the one not firing. Originally when I created this post, it would run on the MAG only or CEN only but would die on the PTO. Now it won't run on MAG only. It only runs on CEN only. Confusing, I know. Lol.

    How do the spark plugs look? Are they oil fouled? Dry and white in color? Dry and black in color? Plugs looked ok actually, all had a nice brown color and I don't recall the PTO looking excessively wet as you would imagine it to look.

    Were the carbs ever addressed? Verify jetting and that they are all clear? Carbs are in sync? Both the CEN and PTO are showing they need a lot more fuel or you risk holing a piston. I just got both of my jetskis. Not sure about previous carb work, however when I ran it before this loss of high end power, it ran excellent through the entire rpm band. Doesn't mean the carbs themselves were perfectly tuned of course, definitely could be a little lean.

    Any signs of fuel spitting out the tops of the carbs when running? Indicating broken reeds. Originally yes, this was why I took it to the mechanic because it just wouldn't go in water. He dove in and discovered two reeds weren't even installed. He installed 2 used ones (he said it was on the MAG and PTO) but didn't look at the CEN.

    How's the condition of the elec box inside? Any signs of water or CORROSION? Electrical box looks great. No sign of corrosion.

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