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  1. #1

    Unhappy Fuel or Timing Issue? Polaris SL 650

    First of all I'd like to thank each and every one of you for developing and preserving such an incredibly vast and in depth array of knowledge for our fingertips! I’ve been reading TONS of great info about these things for the last 4 or 5 days now, and because of this site, I’m probably going to give my very temperamental ski another chance…

    So here’s the scoop with my 1995 Polaris SL 650:

    She’s always been a bit tough to start and it turns out, I had a faulty circuit breaker. I ordered a new one and in the meantime, swapped in a brand new battery and a 15A automotive fuse… and Voila! She fired up immediately.

    Once in the water the ski fired up again no problem but was emitting a rather loud whistle or whine that sounded like an electrical relay acting up or something and very much resembled the tone emitted when hitting the STOP button. I shut off the ski, restarted and the same thing. Gave it gas, idled it a minute, ski ran fine except for the noise. Throughout the 20 minute “No Wake” ride to the lake though, the noise gradually became quieter until it disappeared completely. This led to me to think the fuel pump was starving or something, but now knowing that it’s a diaphragm pump, I don’t think that's possible…

    The ski ran great all that day. The whistle/whine always reappeared on start up but quickly went away. (On a side note, last season I remember hearing a similar ping/chime when my ski would land hard off a wave, but unlike now, it always went away in about a second or two…)

    Two days later (today) we went out and the ski fired right up had a brief whine-fit and ran awesome—perhaps the best she’s ever run in the dozen or so times I’ve put her in. We went about 3 miles down the shoreline without issue, EXCEPT during one WOT sprint (about 2 miles in), the ski bogged down. I let off the throttle in alarm for second and gave it some gas and it was fine again.

    We proceeded another mile out and made it all the way back without issue until the last 1/4 mile (a 6 mile round trip), when the ski suddenly bogged and died. She fired right back up went about 400 feet and died again. She fired up with some help from the choke this time and went about another 200 feet before dying out. Started really quite hard this time and with 1/4 choke I managed to cruise a little while before sputtering out. After several more restarts and some choke/throttle maneuvering, I was able to nurse her back to camp where I let it sit for an hour or more to cool off.

    When I went to restart, she started but wouldn’t stay running and throttle just bogged her down.

    SOOOOooooo….

    Once home I started doing some more research and now realize that I’ve been neglecting my poor 17 year old ski these last 3 years (this is my third season owning it)

    I’ve since ordered a Mikuni TRIPLE OUT PUMP DF-52-92 and currently have a “Mikuni SBN Carb Rebuild Kit” from SBT sitting in my shopping cart. But does anyone know if this SBT kit is authentic Mikuni or of equal-quality parts? I’m new to this jet ski part ordering experience and couldnt tell you Jane from Harry from Dick in that biz...

    I started investigating my ski in detail as well. And while the gas lines look like they might be original, they are in really nice shape—no gunk or cracks

    I also noticed that the RES switch runs on a separate pickup line to the fuel tank and decided to see if it would start and run off that line, which she did, but when I switched back to ON it ran off that line as well. And I cant really tell how it’s running though b/c when it’s out-of-water there’s no real load exerted on the engine.

    I pulled the in-line fuel filters for the RES and ON lines and neither had any foreign particles in them and I could blow thru them both ways no problem. The water separator looked clean except that there’s an orange or red colored ring lying kind of crooked in the bottom. Did that fall off of something or is that some kind of water indicator?

    I tried to slide the large metal tube out of the gas tank to see if pick up tubes are full of debris or something, but it gets stuck at the bottom of the tube. Can I just yank it out? I can be more forceful but thought I should ask before doing damage. As far I can tell they had to slide it in through that hole, as I can’t imagine it was somehow assembled inside the tank…

    The carb cover also seemed to have a decent amount of water splashed in it. Is that normal? The flame arrestor had some water on it as well. It didn’t look “swamped” or anything and I didn’t roll the boat, but I wouldn’t have ever thought I’d find any kind of water inside the carb cover though either… (but we were riding 1-3 footers today)

    I pulled the spark plugs too. They all looked identical and seemed very clean and well burned. None of them was white or chalky (indicating too lean?) but none was black or sooty either. The plugs only have two days of running on them, as I always replace them each season and this has been their first weekend out.

    However… and this may be the BIG however,

    When I peered down into each cylinder with a flashlight the MAG and CNT cylinders definitely show some signs of disintegration. I don’t exactly see a hole, per se, but there’s certainly a ‘bullseye’ like dent forming there. The PTO cylinder on the other hand shows nothing of the sort, although it is definitely much “dirtier” looking than the other two. But I’ve never looked at them before so I couldn’t say if this just happened or has been an ongoing issue for who-know-how-long….

    Still I ordered three head gaskets from SBT as I figure this news warrants some closer inspection. Anyone have any experience with these guys? Their customer service guy seemed somewhat knowledgeable when I talked to him on the phone…

    Might today’s engine behavior be more of a timing issue than a fuel issue? What happens when the woodruff key sheers? Is it characteristic for the engine to run for shorter and shorter time periods as the crank/flywheel begins to ‘slip’ or does the engine just immediately get so out of time that it will die right away?

    What other factors might contribute to some sort of timing slip?

    Any ideas, look-fors, observations or advise would be truly appreciated. I currently do not own a compression guage or leak-test device and hesitate to rip apart the whole engine to leak-test at the moment…. My gut tells me that while my fuel system may have been neglected these last three years, it’s something else. The ski ran just sweet these last two days.

    On a side note, if this engine does need an overhaul, how long and hard is it to pull and engine? I just bought a factory service manual but haven’t had much time to cruise through the nearly 600 pages…

    Also if anyone knows if SBT sells quality parts I’d love to know so I can get my order for carb rebuild and head gaskets in as soon as possible.

    Thank you all for your time, thoughts and efforts! Cheers!


    PS: Probably a newbie error on my parts, but the site times out WAY too quickly. I made the mistake of first typing this post into the “Post a Thread” field, went to submit it and *** Poof! *** it was gone cuz I timed out in the process of writing it, with no way to get it back… I’m not complaining (too much) but having to remember what I wrote to type this up twice was a bit frustrating…


  2. #2
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Quote Originally Posted by tripn4days View Post
    First of all I'd like to thank each and every one of you for developing and preserving such an incredibly vast and in depth array of knowledge for our fingertips! I’ve been reading TONS of great info about these things for the last 4 or 5 days now, and because of this site, I’m probably going to give my very temperamental ski another chance…

    So here’s the scoop with my 1995 Polaris SL 650:

    She’s always been a bit tough to start and it turns out, I had a faulty circuit breaker. I ordered a new one and in the meantime, swapped in a brand new battery and a 15A automotive fuse… and Voila! She fired up immediately.

    Once in the water the ski fired up again no problem but was emitting a rather loud whistle or whine that sounded like an electrical relay acting up or something and very much resembled the tone emitted when hitting the STOP button. I shut off the ski, restarted and the same thing. Gave it gas, idled it a minute, ski ran fine except for the noise. Throughout the 20 minute “No Wake” ride to the lake though, the noise gradually became quieter until it disappeared completely. This led to me to think the fuel pump was starving or something, but now knowing that it’s a diaphragm pump, I don’t think that's possible…

    The ski ran great all that day. The whistle/whine always reappeared on start up but quickly went away. (On a side note, last season I remember hearing a similar ping/chime when my ski would land hard off a wave, but unlike now, it always went away in about a second or two…)

    Two days later (today) we went out and the ski fired right up had a brief whine-fit and ran awesome—perhaps the best she’s ever run in the dozen or so times I’ve put her in. We went about 3 miles down the shoreline without issue, EXCEPT during one WOT sprint (about 2 miles in), the ski bogged down. I let off the throttle in alarm for second and gave it some gas and it was fine again.

    We proceeded another mile out and made it all the way back without issue until the last 1/4 mile (a 6 mile round trip), when the ski suddenly bogged and died. She fired right back up went about 400 feet and died again. She fired up with some help from the choke this time and went about another 200 feet before dying out. Started really quite hard this time and with 1/4 choke I managed to cruise a little while before sputtering out. After several more restarts and some choke/throttle maneuvering, I was able to nurse her back to camp where I let it sit for an hour or more to cool off.

    When I went to restart, she started but wouldn’t stay running and throttle just bogged her down.

    SOOOOooooo….

    Once home I started doing some more research and now realize that I’ve been neglecting my poor 17 year old ski these last 3 years (this is my third season owning it)

    I’ve since ordered a Mikuni TRIPLE OUT PUMP DF-52-92 and currently have a “Mikuni SBN Carb Rebuild Kit” from SBT sitting in my shopping cart. But does anyone know if this SBT kit is authentic Mikuni or of equal-quality parts? I’m new to this jet ski part ordering experience and couldnt tell you Jane from Harry from Dick in that biz...

    I started investigating my ski in detail as well. And while the gas lines look like they might be original, they are in really nice shape—no gunk or cracks

    I also noticed that the RES switch runs on a separate pickup line to the fuel tank and decided to see if it would start and run off that line, which she did, but when I switched back to ON it ran off that line as well. And I cant really tell how it’s running though b/c when it’s out-of-water there’s no real load exerted on the engine.

    I pulled the in-line fuel filters for the RES and ON lines and neither had any foreign particles in them and I could blow thru them both ways no problem. The water separator looked clean except that there’s an orange or red colored ring lying kind of crooked in the bottom. Did that fall off of something or is that some kind of water indicator?

    I tried to slide the large metal tube out of the gas tank to see if pick up tubes are full of debris or something, but it gets stuck at the bottom of the tube. Can I just yank it out? I can be more forceful but thought I should ask before doing damage. As far I can tell they had to slide it in through that hole, as I can’t imagine it was somehow assembled inside the tank…

    The carb cover also seemed to have a decent amount of water splashed in it. Is that normal? The flame arrestor had some water on it as well. It didn’t look “swamped” or anything and I didn’t roll the boat, but I wouldn’t have ever thought I’d find any kind of water inside the carb cover though either… (but we were riding 1-3 footers today)

    I pulled the spark plugs too. They all looked identical and seemed very clean and well burned. None of them was white or chalky (indicating too lean?) but none was black or sooty either. The plugs only have two days of running on them, as I always replace them each season and this has been their first weekend out.

    However… and this may be the BIG however,

    When I peered down into each cylinder with a flashlight the MAG and CNT cylinders definitely show some signs of disintegration. I don’t exactly see a hole, per se, but there’s certainly a ‘bullseye’ like dent forming there. The PTO cylinder on the other hand shows nothing of the sort, although it is definitely much “dirtier” looking than the other two. But I’ve never looked at them before so I couldn’t say if this just happened or has been an ongoing issue for who-know-how-long….

    Still I ordered three head gaskets from SBT as I figure this news warrants some closer inspection. Anyone have any experience with these guys? Their customer service guy seemed somewhat knowledgeable when I talked to him on the phone…

    Might today’s engine behavior be more of a timing issue than a fuel issue? What happens when the woodruff key sheers? Is it characteristic for the engine to run for shorter and shorter time periods as the crank/flywheel begins to ‘slip’ or does the engine just immediately get so out of time that it will die right away?

    What other factors might contribute to some sort of timing slip?

    Any ideas, look-fors, observations or advise would be truly appreciated. I currently do not own a compression guage or leak-test device and hesitate to rip apart the whole engine to leak-test at the moment…. My gut tells me that while my fuel system may have been neglected these last three years, it’s something else. The ski ran just sweet these last two days.

    On a side note, if this engine does need an overhaul, how long and hard is it to pull and engine? I just bought a factory service manual but haven’t had much time to cruise through the nearly 600 pages…

    Also if anyone knows if SBT sells quality parts I’d love to know so I can get my order for carb rebuild and head gaskets in as soon as possible.

    Thank you all for your time, thoughts and efforts! Cheers!


    PS: Probably a newbie error on my parts, but the site times out WAY too quickly. I made the mistake of first typing this post into the “Post a Thread” field, went to submit it and *** Poof! *** it was gone cuz I timed out in the process of writing it, with no way to get it back… I’m not complaining (too much) but having to remember what I wrote to type this up twice was a bit frustrating…
    Welcome to the Hulk.

    Wow, quite the first post......


    Ummmm, no, the SBT carb rebuild kit is NOT genuine mikuni parts. I'd suggest getting the carb rebuild kits and prob the fuel pump too from john Zigler at rock County Jet Ski.

    But before you do that, remove your cyl heads and get a real good look at what's going on. Take some pics to upload on here too.

    It sounds like you're almost in need of a rebuild. No sense in spending $$$ on upgrades yet, if you need to redo the motor.

    It doesn't sound like a timing issue. Definately sounds fuel related. Esp if the choke seemed to help.

    Lets see what you got, and we'll go from there first.

    Read through this http://www.greenhulk.net/forums/show...-750-780-785-s

    And the links at the bottom of K447 posts for all the info listed for Fuji (blue) engine fuel problems

  3. #3
    Thank you for the quick response. The choke only worked for a little bit at first but as the event went on, the choke didn't make a difference one way or the other, esp after the hour plus cool down.

    I guess I'll tear the heads off and see what I'm working with... I'd hate to keep the other ski out of commission while I fix this one though... How do you guys get your skis on and off the trailer for major repairs like this? I was thinking of ratchet straps around the rafters in my garage... or am I just crazy?

  4. #4
    i would make a cradle, cheap and easy. As far as getting it off, it should slide right off with a little man power.

  5. #5
    OKAY... NEWEST DEVELOPMENTS:

    Pulled the heads today. Again, spark plugs look perfect.

    Turns out my flashlight was deceiving me. MAG and CNT cylinders look perfectly domed and show no sign of lean burn down. BUT, what IS rather odd is that the PTO cylinder definitely shows signs burn down. I have no idea how far burn down can get before it becomes a unsafe or a hole; but while not perfect, hopefully this one's got some life left in it.

    Spark plugs were all identical and a nice chocolate brown color, so I doubt lean out was my issue yesterday.

    MAG:
    Click image for larger version. 

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ID:	246279

    CNT:
    Click image for larger version. 

Name:	CNT Cyl.jpg 
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ID:	246281

    PTO:
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Name:	PTO Cyl.jpg 
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    1) Isn't it rather rare for the PTO to go before the rest of them since PTO is closest to the pump?
    Bad fuel rate to just this cylinder (ie clogged/restricted line)?

    ** I'm left wondering if the original bog i described in OP was actually the PTO carb clogging momentarily, freeing itself up and then reclogging on the last leg of my return trip.



    2) Going back to my Original Post, is it normal to have water splashed all around inside the carb cover and across the flame arrestor? I would think this would make it prone to sucking H20 into the chamber....

    3) What happens when the woodruff key sheers? Is it characteristic for the engine to run for shorter and shorter time periods as the crank/flywheel begins to ‘slip’ or does the engine just immediately get so out of time that it will die right away?


    And lastly...

    4) Probably just spitballing here, but since I've pretty much completely disassembled it already, I want to check the tank puck up. There are no rubber tubes to rot, but when tried to slide the large metal tube out of the gas tank to see if pick up tubes are full of debris or something, but it gets stuck at the bottom of the tube. Can I just yank it out? I can’t imagine it was somehow assembled inside the tank…

  6. #6
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    All 3 pistons are lean. (lack of fuel) The PTO being close to complete failure.

    You need to do some fuel system upgrades if you haven't already.

    PTO are prone to early failure because of failing rear crank seals, and because it's the first to see water intrusion if it makes it's way into the FA.

    Is it normal to have water splashed across it? NO You really shouldn't have any water inside the hull.

    When the woodruff key shears, you normally have irratic running, hard starting, backfiring, weak spark, or no spark.

    There's a black cap on the bottom of the fuel pick up tube that's getting hung up. It's only held on by a very small brass nut and threaded rod. DO NOT just yank it out. You need to kind of lift and lean the tube towards the front to get the cap to clear the opening.

  7. #7
    Thank you! THATS what I needed to know! I started pulling carbs but need to refer to FSM for how to get the bolts top bolts off the head/manifold... Tips?

    How could you tell they are all running lean? What's the look-fors of that?

  8. #8
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Carbs, head bolts/manifold???? Huh?????

    There are 6 12mm nuts on the under side of the carbs that needs to come off. Then disconnect the choke and throttle inkagesm finally the oil pump linkage,a d they will come off.

    TIP: use a stubby (short) 12mm wrench to get the nuts off. And place a towel under your work area to catch anytjhing that falls so it doesn't end up under the motor.

    Reasd through this for ALOT of info you seek. Make sure to click the links provided.

    http://www.greenhulk.net/forums/show...-750-780-785-s

  9. #9
    1FASTXC's Avatar
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    There is no "wash" on your pistons, that's how he knows they are lean. Wash is small spots on the top of your pistons where the fuel entering into the cylinder keeps the top of the piston cool and "washes" the carbon off. If you use the search function you can find more on that i'm sure. The triple outlet pump is definitely a common upgrade that most people do. I personally have ran a couple of my fuji powered skis with the stock pump with a fresh rebuild with no problems. I don't want to argue with anyone about it because everyone has their own opinion, but the stock pump can and will supply enough fuel to support the engine with the right adjustments. The 650 i have right now has the stock pump and will run wide open all day with it on 87 octane, but i made adjustments to the carbs to make it work. One thing people need to keep in mind is that when these skis were built there was no ethanol in the fuel at the time. Now pretty much all fuel has at least 10% ethanol(except premium in some places). With ethanol in the fuel the mixture needs to be around 5% richer to compensate for that. If you're running the stock carb settings, they can be lean. I did burn a pto piston on the 650 i have now with stock carb settings. I have since readjusted them and haven't had an issue. i had to open up the main screws richer than the factory settings.

  10. #10
    That makes a lot of sense. Thank you. I ordered some parts online and will have to await their arrival before moving further. I'm assuming I'll have to do a leak down test to see if the rear crank seal is leaking?

    What kind of time/hassle is it to do a crank seal if needed?

    All the cars I've ever owned and worked on were FI, so this carburetor tuning stuff is a bit intimidating. I have a grounded understanding of how they function, but when it comes to tuning, for say a 5% richer mixture, what does that look like? How many turns is that and how can I quickly tell if the new mixture I create is rich enough?

    Chapter three of the FSM talks about the chart only being an initial setting and final adjustment needs to be made "in the water" with boat attached secure to trailer. Would it be safest to intentionally run a bit more rich to make up for ethanol, despite slightly poorer gas mileage?

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