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  1. #1

    1999 SLTH 700 won't rev past 5600

    The recent history of this ski isnít pretty. I purchased it over a year ago. The PO ran it on a hose and told me that it had the ignition update kit, but needed a carb rebuild and basic tuneup. On the hose it sputtered, but appeared to run well enough. I took it straight to an independent jet ski tech with a good rep and let him do the work. He ran it on a hose, and there wasnít any noticeable issues with running. I took it to the water for the first time and it wouldnít rev past 2000 RPM. Back to the tech with it. He went with me to the water and played with the carbs, but was still not able to get it up on plane.

    The wife was getting antsy (for good reason) so I decided to take up further repairs on my own. The first day that I dove into it, I discovered the timing was off. WAY off. I pulled the stator cover to find the flywheel improperly installed. First guy wasnít as reputable as I thought, or he should have at least checked timing on a tuneup. I was unable to pull the flywheel myself. In fact, I broke my puller trying. The engine had to come out. Being new to jetskis, and busy as heck with work and life, I took it to a reputable SHOP. They pulled the engine and were able to remove the flywheel. They said it looked like it was hammered on with a sledge. I asked them to go ahead and retune. Obviously a carb tune with improper timing isnít going to fly. They also Ďtunedí it on a hose. First run out, I was able to get it up on plane, but only if I leaned over the handlebars. Top speed in the 20mph range. I believe the revs were in the 4000 range.

    At this point I had spent 50% of original purchase price on repairs and it still was slower than my bass boat with a 25hp Johnson. I put it away intending to hawk it next (this) season.

    For whatever reason, I thought Iíd give it another go. I bought a new AGM battery because the one in it died over the winter. I tried to revive it through several de-sulfating sessions, but it was a goner. I started researching things on this and other sites. I discovered the gray tempo fuel line issue. Sure enough, I have them and theyíre green as an unused boat ramp. Swapped out the lines. I look to make sure that I do in fact have the ignition update kit. Iím still not sure about that one. The CDI has a 4xxxxxx part number, but it has been painted over, and I didnít see anything hand written. I have a spare black wire coming out of the electrical box. My research says that it was a ground from the stator to the battery that needed to be cut and taped with the ignition update. I also read that the original CDI red/purple wire needed to be moved to the orange supply from the LR module. This had not been done. I couldnít find anything saying it was necessary with an ignition update kit, but I took a leap of faith and tried it anyway. The ski never had a hot start (or any start) issue. It would always start and idle well. While I was in the garage I checked compression and it was a respectable 135/140 mag/pto.

    1 possibly 2 issues resolved. Lets try it on the water! I take it out and after some initial coughs and sputters Iím getting up on plane like before. Still not breaking the 4xxx mark. The sputters got less frequent, and eventually, it was running at 5xxx WOT and relatively smooth. It felt like it didnít have much power on turns, and definitely had a flat spot in the power band around 2xxx. The fact that I was able to stay on plane in a turn was a marked improvement. I call it success and go home.

    It was a small step, but Iím still not there. What could have limited the revs to the mid 5k range? What do I need to look for next? Should I run some seafoam in a tank and see if the green crap got into my freshly rebuilt carbs? Will these skis hit the 7200 RPM redline? If so, will they hold it for a while? I have a spare light blue/gray wire. Itís the same color as the wire from the stator to the CDI, but has a different plug. I canít remember what it came out of at this point. Any thoughts? Is it likely/largely possible that the ignition system is limiting revs or losing spark in this range? I'm not sure I could even ride and hold a timing gun at that speed. Can I go WOT in reverse? I wasn't sure if it was unhealthy for the reverse flapper thingy. I made the mistake of revving in forward, and ran it over the trailer winch...

    ---------- Post added at 02:12 PM ---------- Previous post was at 02:03 PM ----------

    Also, I forgot to mention that the PO had removed the oil pump. He left the tank in the ski about 1/2 full so that the gauge would see it. I removed the tank and put a 33ohm resistor across the terminals that the sender was connected to. I'm running 40:1

  2. #2
    Click avatar for tech links/info K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada
    Since the Tempo fuel lines were still on there after the carb 'tuning', then there is a good possibility that the junk from the fuel lines has clogged the internal filters inside the carbs. The only way to be sure is to remove the carbs, take them apart, and clean/rebuild them yourself. You didn't say whether either of the previous mechanics actually rebuilt the carburetors.

    The sputtering suggests the carbs are not right, or there is some other fuel system problem.

    Don't bother with the Seafoam, or any other in-the-tank fuel additive product. Clean the fuel system and carbs directly, by taking them apart, inspecting, cleaning, and correcting any problems you find. There is no short-cut for this.

    A well running engine will rev in the water into the 6000+ RPM range. It will also feel strong, and will jump onto plane quickly.

    If you want to test while on the trailer, the front of the ski must be strapped DOWN to the trailer. Not just using the bow winch strap. BTW, normally the strap for the bow winch should run under the front roller, then clip to the bow hoop. Between the two bow straps, the front of the hull should be unable to move up or forward, no matter how much power you apply. And the rear of the hull should also be well strapped down, of course.

    You can apply throttle in reverse, but the results are not useful. The reverse thrust pushes aerated water into the jet pump intake, so the jet pump impeller easily spins in the bubbles. Not useful.

    Do not run the engine hard for more than a few seconds at a time if you are not getting full power. It is very easy (and it can happen quickly) to burn down a piston from lean fuel burn, if the power problem is caused by weak fuel delivery to any of the cylinders.

    You really need to be 100% sure the fuel system, from carbs to fuel tank to hoses, is 100% good. Clean, tight, and correct. No air leaks, not gunk.

    If you want to be sure about the ignition update, an ohm check of the stator coils will tell you. The updated Gen III stator has very different coil resistances than the older stators.

    If you want to keep the oil tank removed, you can re-locate the 33 ohm resistor to inside the electrical box, where it will be protected from water and stay out of trouble.

  3. #3
    I was afraid someone would say that. The last carb I rebuilt was on an 85 Chevy. I have the manuals, so I guess I can rebuild these too. The first guy I took it to supposedly rebuilt the carbs, so itís frustrating that he didnít catch the fuel line issue. Assuming he actually took the lines off, he should have noticed something wasnít right.

    When you say 6000+, are we talking upper or lower 6k? I would think upper with a stated redline of 7200. After the intial sputtering died out, it would get up on to plane relatively quickly. It would bog a bit just off idle around 2k, but quickly pick back up. My estimation is that there is enough power to get myself (250lb) and my wife up on plane if it needed to. After the change of wiring and fuel lines, I no longer needed to lean forward. Solo, I hit about 35mph.

    The strap was run over the top, but I didnít think it would be much of an issue until the ski jumped over the winch. I didnít back it all the way into the water, and it was a pretty steep ramp. I figured the weight of the ski would keep it stuck to the boards, but that was obviously bad math. I purposely took off the back strap afraid the weight of the trailer might sink the back too low. Lesson learned. Iíll look into running the strap under. I might have to adjust the roller as that would put the ski farther back on the trailer.

    Good info on reverse. I was afraid of breaking something. I guess it wouldnít have been a useful test anyway.

    Iíll check out the resistances on the stator coils.

    I put the 33 ohm resistor inside the electrical box. Maybe I didnít state that clearly. I removed tank, sender, and wiring in tact. It still works, so maybe somewhere, somebody would want to buy it.

    Thanks for the suggestions.

  4. #4
    Click avatar for tech links/info K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada
    Quote Originally Posted by litebrite2001 View Post
    ... When you say 6000+, are we talking upper or lower 6k?

    ...I removed tank, sender, and wiring in tact. It still works, so maybe somewhere, somebody would want to buy it...
    Strapped to the trailer, the max RPM may be a little less than when it is flying across the water. Standing still, the jet pump has a little more load than when the hull is at speed.

    The exact RPM depends on a bunch of factors. Everything from air temperature to carb tune to engine condition. If you get 6500RPM, you are right in the ball park. Some guys will see 6800+ while others may only get 6350.

    Running well, that engine puts out about 100HP, so it does have the potential for strong thrust from the jet pump

    Hang on to that oil tank. Later on, you may find the reduced oil consumption (and therefore oil cost) and the convenience of refueling with straight gasoline to be compelling.

    The Polaris oil pumps tend to be reliable. The key is to maintain the rest of the oil system, especially the hoses and clamps. Fresh oil hoses and snug clamps generally result in a trouble free lubrication system.

  5. #5
    Just an update. I pulled the carbs off last night and went through them. I freaked for a minute when I noticed that there was no high speed needle. I thought maybe it had been taken out or something. There was no green goo to speak of. I even dropped the carbs in my ultrasonic cleaner before dousing them with carb cleaner and reassembling. I did find 2 possible issues though... The fuel pump gasket was installed incorrectly. I'm guessing this was done by the first guy I took it to. He was supposed to rebuild the carbs, afterall. Anyways, the gasket wasn't sitting flush under the diaphragm and was only barely covering the metal. I'm assuming it was the first guy again, but the low speed needles were not even close to where they should be. The PTO carb was almost 2.75 turns out and the MAG carb was 2.25 out. I don't know who or why, but the limiters are also missing. The needles all looked good and the screens looked new. The jets had no visible varnish.

    I'm going to open the electrical box tonight and check the stator. I'll probably go ahead and check the coil resistance too. I won't know if any of this did any good until Saturday.

  6. #6
    It has the stator update. 5.x ohms instead of 1200. I took it out Saturday and it still had the flat spot around 2000 RPM. I richened it 1/8 turn on both low speed needles. Flat spot is no more. The first couple of minutes it was still wanting to cut out below 5600 RPM, but only for the first few minutes. I'm guessing that I'm just too fat, because the most I got was 6100 RPM and 40mph. It pulled well up to that point, so... diet is the solution?

  7. #7
    MSX 150 guy lives on Mr. GP1800's Avatar
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    Jun 2010
    Milwaukee WI
    Im not sure but I think you should see 6400-6600 on a 700

  8. #8
    Zombie thread is undead.

    I took the ski out last memorial day and it is still a spud. I was so frustrated after that I took it to a family member's house, and it's sat there since. It will run well for a little while (15-20 min), then it will go back to sputtering and cutting at 4000 rpm. It's not just rev limited to 4000 rpm, it sputters up to that point and no further. The weather is kinda nice, so I thought I would give the POS another go this year.

    Any suggestions for troubleshooting an intermittent problem? The carbs and pump have been rebuilt. The fuel lines were replaced. The stator has been updated. No warning lights, and the engine appears to be running at a reasonable temperature. I don't believe it is temperature related though, because it happened a couple of times when cold, and after feathering it for a few minutes it would get up and go.

    The CDI is a PVL P/N 4010803. That number has been covered with yellow marker, but no other number was written on the front. I'm going to take it off and look at the back this evening.

  9. #9
    MSX 150 guy lives on Mr. GP1800's Avatar
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    Jun 2010
    Milwaukee WI
    Have you checked compression? New BPR8ES plugs? Post a pic of the open electric box. We can tell you what you have in there. Is the grey wire from the CDI connected to anything? If it is try disconnecting it. I have that exact same ski and I get 6600-6700 RPM out of it. Have you verified proper jets in the carbs?

  10. #10
    New BPR8ES plugs gapped at .028" last spring. I checked them again tonight. The gray wire with a spade connector is taped off. I believe it is the one that would go to a rev limiter... if it existed. Carb jets are correct. That was verified by me last year when I rebuilt them. I rechecked compression and it has decreased a significant amount, but I'm not too worried about it yet. Keeping in mind that the ski has sat for almost a year and the test was done on a room temperature motor, I got 125/135. That's slightly beyond the spec of within 5% of each other.

    On the back of the CDI '448' is written with yellow marker. The coil pack is PVL PN 4010175

    Starting at page 7.32 of the 1999 Polaris SLTH service manual, there is a procedure for checking out the ignition system. Basically none of it appears to apply to my setup due to the update. I don't have a manual for testing the newer setup. Random testing yielded the following:
    Exciter coil #1 (black to purple) is 5.5ohms
    Charging coil (Yellow to red/purple) is .7 to .8 ohms
    Hall wires are open circuit
    the Mag spark plug wire has a resistance of 3kOhm from the spark plug boot to the point it plugs into the coil.
    The PTO spark plug wire has a resistance of 2.xkOhm from the same points
    Coil primary (Low voltage side) reads shorted to my meter.
    coil secondary (High voltage) reads 2.98kOhm
    The spark plug boot is just that, a boot. There's no resistor in it. The resistance measured on the wire is in the wire itself. The wire appears to be constructed as a coil wrapped around a string inside a high voltage jacket. Didn't get a good pic, but it's not your everyday spark plug wire.

    And the pics:

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