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  1. #1
    StevoH@O's Avatar
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    95 SLT Rebuild - Revving High

    I've been busy riding but now have a project ski being prepared for my Brother - in - Law. Here is what has been done: New primed and replaced fuel lines. Replacement front piston and honed out cylinder. New head gasket. Bled out oil pump. Placed new triple outlet fuel pump to replace out single outlet pump. Primed main line. primed carbs. Started but revved really high - like 5700 rpm and if I throttled it up, it seemed to be under load but did not change the overall revving issue. I did not mess with carb settings from previous owner but throttle positioning seems consistent with other racks.

    So I had not replaced the pump and I'm wondering without that "load" it is allowing the RPM's to spike so high. I'm in my driveway and not at a water site.

    Could the reinstallation of the pump be the solution? is there anything else I should be doing? I figured the GreenHulk Crew could offer really good ideas and suggestions.

    I waited, and started a second time with the same outcome after 15 seconds.

    Thanks and have a safe and happy 4th!

    Go Bucks!!!


  2. #2
    BlueFishCrisis's Avatar
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    5700 is high. I would expect a slight change with the pump installed but not much. The Fuji motors usually idle around 3700 rpm out of the water. I would just adjust the throttle speed screw down til you get to about 3700 rpm. If adjusting the screw has no effect, you may have an air leak somewhere....

  3. #3
    StevoH@O's Avatar
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    I'm sending this scenario back into the expert's hands for suggestions. So I have seen that there are a host of "triple outlet" fuel pumps out on the market with various prices. The previous owner had purchased this particular triple outlet pump and I installed into the carb distribution pathway. I had no packaging, just the new, fresh pump. Well as I have examined more sales and marketing pages on fuel pumps. I see that there is differing output measurements for pumps that look nearly identical. So Polaris experts, what was the output rating/volume for the old single outlet fuel pump? And is there identifying marking on the new fuel pump to identify if I have a good match or if I have a pump forcing x2 or x3 the fuel output volume to my original carbs forcing the high rev scenario at start up?

    So the bottom line: what is the OEM pump output rating for the original fuel pump? If I know that, I can easily order a matching triple output volume that may correct my over-revving issue. Thank Subject Matter Experts! I appreciate the help!
    Steve
    Bucks Did It!!

  4. #4
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    The original Mikuni round single outlet fuel pump was rated at 35L per hour.

    Mikuni American Corporation

    I have not read many people having issues with higher output fuel pumps causing problems.

    If there was a piston damaged, it may have been from an air leak or a fuel supply issue. Normally not from the fuel pump. A lack of a fuel restrictor on 650's and 750's can cause a low fuel pressure problem.

    1. Have you done a leak down test to verify no air leaks present?

    2. Do you have the original fuel shut off valve still installed? If so, I'd replace that.

    3. Are your fuel hoses and clamps in good order?

    4. Do you have an in-line fuel filter installed? Does it appear to be full?

    5. Have the carbs been THOROUGHLY gone through? Or rebuilt?

    6. Are the carbs properly set/adjusted?

  5. #5
    johnsonmtz's Avatar
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    Xlint is right, 35 LPH is the OEM pump output. This is link is a perfect replacement for what you need: https://www.partsgiant.com/p356931-m...BoC-WQQAvD_BwE

    You need to follow steps 1-6 that he outlined. When you're working on old stuff, never assume the previous owner had everything right. There are a lot of people that turn knobs without knowing what they are doing. The low and high speed needles must be exactly correct and those are possible sources of your issue. The best thing is to get 3 original Mikuni SBN kits, rebuild the carbs, set the pop-off pressure, and verify needles are correct.

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