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  1. #1
    jbizub's Avatar
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    94 SL 750 Runs Great at first then loses power

    Hi everyone, sorry if this is posted already, if it is just let me know. I searched but didnt come up with anything. When I first start the ski up on a cold start it starts right up and runs great. After about 10mins or so of ridding I will gradually loose power and then eventually I can only get about 4300 rps out of it. Ill shut it off and let it sit for 10mins or so and then it works fine with full power for about 5 or less minutes and then the same loss of power happens. What could be causing this? Also sometimes when I go to use the primer I cant pull it out, When I pull hard it will come out a little bit goes right back in like a spring was holding it back, and no fuel gets pushed through. It seems like theirs a vacuum holding back or something? Any ideas lol

    Thanks!!


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Sounds like the fuel tank venting check valves are stuck closed and there is a vacuum being created as the engine draws fuel out of the tank.

    Next time this happens, stop and crack open the gas cap. If there is a big whoosh of air going into the tank (relieving a vacuum), then the tank venting is not working. Confirm by opening and re-closing the gas cap, then try riding it again.

    I would suggest upgrading to the 1995 venting arrangement which uses two check valves. Details can be found in the Fuji section from my signature links.

  3. #3
    jbizub's Avatar
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    That's what I was leaning towards, I thought that might have been what was causing the issue.

    The problem happened at the end of last season so I hope to put the ski in this weekend.

    I'll report back if there's hissing when taking the cap off. Thanks Again!!

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    If you want to get ahead of the game, go ahead and order the 1995 check valves and tee fitting, then upgrade the venting system straight away.

    There is a risk of damaging the engine from lean fuel delivery as the vacuum inside the tank builds up. Every time you ride it with the venting not working, you risk engine damage.

    The major clue is the primer pump knob getting sucked back in. That doesn't happen unless there is a vacuum inside the fuel lines, which means there must be a vacuum inside the fuel tank too. And the only way for the tank to have a vacuum is if the venting check valve is stuck closed (no venting despite the pressure differential).

  5. #5
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Are you able to place your hand on the cylinders when it loses power? (wondering if you're overheating)

  6. #6
    jbizub's Avatar
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    Ok i will defiantly order them asap!! Would you be able to provide me a link where I could get the parts? Also my fuel selector only works on reserve and i know from reading up this could cause issues of leaning out and damage. Where could I get a new selector? Thanks So much!!

    ---------- Post added at 08:36 PM ---------- Previous post was at 08:33 PM ----------

    Oh and to answer the overheating question, I dont think it is overheating, the gauge never said overheating(not that I would trust the gauge fully). But i know it does work because it came up as hot once and i pulled into shore asap and there was seaweed over the inlet. But that was a while back before I had this issue. I did pull the plugs and they were brown with no white at all.

  7. #7
    jbizub's Avatar
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    I Tried to look up exactly what parts you listed but im a little confussed and want to make sure I get the right ones. The 2 valves that I see listed are the VALVE,VACUUM CHECK, and VALVE,CHECK,RELIEF. Are these the 2 I need? Thanks again

  8. #8
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by jbizub View Post
    I Tried to look up exactly what parts you listed but im a little confussed and want to make sure I get the right ones. The 2 valves that I see listed are the VALVE,VACUUM CHECK, and VALVE,CHECK,RELIEF. Are these the 2 I need? Thanks again
    That sounds correct.

    What part numbers are you looking at?

    Do you also need the little tee where the two check valves connect together?

    7052118 VALVE,VACUUM CHECK
    7051015 VALVE,CHECK,RELIEF
    7052111 FITTING,TEE

  9. #9
    jbizub's Avatar
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    Yep those were the part numbers and i will order a new t also. Do i need the grommet vent, 5410682?

  10. #10
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by jbizub View Post
    Yep those were the part numbers and i will order a new t also. Do i need the grommet vent, 5410682?
    Not unless you have lost or damaged the original rubber vent fitting on the ski.

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