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  1. #1
    TuckrD's Avatar
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    Power Vavle Failure (need help diagnosing)

    Hello fellow GH forum contributors. I have a powervalve that is working sometimes and not others. When I go for the holeshot, the valves open and then shutter and close. They will not cycle again unless I come to a full stop. When I cut the engine, they do their "cleaning" cycle, so I know they are receiving signal even after the failure.
    To trouble shoot them I have cleaned the housings, done the adjustments, and have WE clips installed. Thinking it was/is a wiring issue, got a new used EBOX, new plugs, new used PV Servo and still no success. the funny part is, they seem to work fine out of the water on trailer before we launch, but once in water, they do the fail sequence as stated above. I have done as much as I know at this point.
    I am mostly confused why on land at the 5k rpm area, they actuate and adjust accordingly, but when in water with load on pump, they open and fail closed. PLEASE PLEASE help with this issue. I have been chasing the cause for over two weeks and many trips to my closest launch site. Thanks in advance.
    Last edited by TuckrD; 06-29-2013 at 10:34 PM.


  2. #2
    TuckrD's Avatar
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    Also, I have tried two separate CDIs and have the same results. I believe it not to be in the wiring from the EBOX as I have tried two different boxes (chance of both being bad rare) and their associated wiring harnesses. The three wires are ground, to the fuses and then to the CDI.
    What signals does the PV's work off of? I gather RPM and Speed?

  3. #3
    mudslanger's Avatar
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    They are out of adjustment. I know you are going to say you have the cables on wright but it is always good to make sure. Just had to throw that out there. As far as the adjustment try to get a lot of slack in the cables then start and stop engine to let PV cycle do this several times to make sure after they cycle you still have slack in them. Then you can put the line up pin in the hole to adjust them without pulling a cable too tight and turning the Pv servo wheel. Once you get the pin in you can start taking the slack out of the cables. Hope this helps.

  4. #4
    TuckrD's Avatar
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    Quote Originally Posted by mudslanger View Post
    They are out of adjustment. I know you are going to say you have the cables on wright but it is always good to make sure. Just had to throw that out there. As far as the adjustment try to get a lot of slack in the cables then start and stop engine to let PV cycle do this several times to make sure after they cycle you still have slack in them. Then you can put the line up pin in the hole to adjust them without pulling a cable too tight and turning the Pv servo wheel. Once you get the pin in you can start taking the slack out of the cables. Hope this helps.
    As far as this goes, I have added slack to the lines, cycled them many time with the power and also by hand, and then made the official line up to the hole in wheel to the block. It is not an issue of them moving, but yet their signal that is received. Open on holeshot, then stutter and "fail" close.
    Last edited by TuckrD; 06-29-2013 at 10:53 PM.

  5. #5
    mudslanger's Avatar
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    The reason I say adjustment is sometimes when people adjust the cables they mistakenly adjust them to we're they are closing too much and the pin WILL line up no problem. Because the pin lines them up in the closed position. The problem is when they are adjusted that way the servo is out of time and the signal being sent from the ECM for them to open is sent the servo is just cycling. That is the reason they close on the hole shot. They are just cycling. You can mistake this as normal operation but they are trying to line up but can't because the servo is not closing on the cycle even if the valves are fully closed them selves. If you haven't posted all the things you have tried then I would say try something else but it points to adjustment.

  6. #6
    TuckrD's Avatar
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    Quote Originally Posted by mudslanger View Post
    The reason I say adjustment is sometimes when people adjust the cables they mistakenly adjust them to we're they are closing too much and the pin WILL line up no problem. Because the pin lines them up in the closed position. The problem is when they are adjusted that way the servo is out of time and the signal being sent from the ECM for them to open is sent the servo is just cycling. That is the reason they close on the hole shot. They are just cycling. You can mistake this as normal operation but they are trying to line up but can't because the servo is not closing on the cycle even if the valves are fully closed them selves. If you haven't posted all the things you have tried then I would say try something else but it points to adjustment.
    I will give it another try tomorrow. This issue just showed up one day. Ski was running, what I call 98% (due to carbs needing tune and also cavitation) and then fell flat on it face. The PV went into this failing mode, and can't get them to go back to normal operation. Again, have tried my original servo motor and another one that I purchased and me issue, so still perplexed. I took the cables and covers off to check the PV swing, and see to be getting their full swing (closed to open and back). As far as timing, if not to line up with the hole, what is the proper procedure not stated in the owners manual (.pdf from CajunDude)?
    This is also the thing, I can have the cable completely off of the servo, but plugged into the wiring harness, and still actuates the same, open on holeshot then fails closed, so no adjustments, no tension. Does the EGT (exhaust gas temp) have any control input into the PV operation. I am running D plate without the chip, did a mod that stopped the alarm, but ski ran well for many hours like this.

  7. #7
    Happily Self-Employed WFO's Avatar
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    probably overreving

  8. #8
    mudslanger's Avatar
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    I haven't read what he posted and usually pull the cables off to make sure they don't bind wile the servo cycles. Then put the cables back on loose to make sure I don't turn the servo. Then just before I take out the slack I hit the start button to let them cycle then I put the pin in and take out the slack making sure I don't tighten one cable more than the other. It doesn't take much pressure to accidentally turn the servo. So when you get the slack out of the cables turn both adjusters the same amount of turns to the cable is just barley taught.

  9. #9
    TuckrD's Avatar
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    Quote Originally Posted by WFO View Post
    probably overreving
    When it is in the overrevving area, I notice the valves open and close to bring the rpms down, but I am sure (90% ish) that this is not attributed to overrevving. The valve opens at the prescibed point in the 5k rpm range out of water, but once I get in water, they will allow for a quick holeshot (maybe less then 15mph) and do what I call the "fail" twitch and go into I guess a limp mode. I have unplugged the electrical connector and operated the PV's manually and able to get into the 50-55mph range leading to believe the valves themselves work as intended ( to relieve gas pressure when engine is working hard), but servo communication is not all there. I have not heard this issue before (searching this site and a few others, including calling a dealership service center).
    Driving me mad to say the least.
    Last edited by TuckrD; 06-30-2013 at 12:39 PM.

  10. #10

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    Quote Originally Posted by WFO View Post
    probably overreving
    Just like Richard is suggesting. The stock CDI will close the valves when the engine over revs. For example, when you are in rough water and you exceed 7400rpms, the valves will go closed. You get a brakes on kind of feeling while riding.

    If you had aftermarket gas valves, this would not happen because the valves no longer depend on an electric signal to operate. If you had an aftermarket CDI, this feature of closing valves at high rpms can be minipulated, and if I am not mistaken, can be eliminated. I've always used gas valves, so do not know for sure.

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