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94XP won't start in water?

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  • 94XP won't start in water?

    I’m new to PCW’s. I have a recently rebuilt 94 Seadoo XP that has developed some really frustrating starting problems. It starts up and runs great on the trailer. However, once in the water it either won’t start or is extremely difficult get running. I’ve even started it up on the trailer just before putting it in the water and it STILL won’t start once it’s in the water. On the few occasions I’ve been able to get it started in the water, I had to hold down the starter button and rapidly pump the throttle handle until it reluctantly sputters and finally starts. Now once running it IDELS FINE and runs GREAT but if I turn it off (when the engines hot) it will not start back up. Of course when I get it back at home (on the trailer) it starts right up.

    I’m getting fuel to the carbs and the starter works fine (until I run down the battery). The spark at the plugs is not a big blue-white spark like it says in the Clymer manual. It’s kind of a weak yellow-orange. When I pull the plugs they appear to be fouled. I’ve put in new plugs and have the same problem. I’ve also dynamically timed the stator at 6000 RPM. Could this be a defective “dual mode coil” (low voltage side) or stator? Any help you could offer would be greatly appreciated.

  • #2
    This is most likely carbs that are out of tune, need to be rebuilt, or a rotary valve cover that's damaged or out of spec.

    Start with tuning your carbs - I would try turning your low speed screws out 1/8th a turn and see if it helps. Also - what RPM does it idle at in the water? If it's set too low, it won't start without throttle, and may not idle very long. You may need to adjust that.

    If tuning doesn't help, check your rotary cover clearance. Remove the cover and manifold (don't pull the vavle off the shaft or you'll need to retime it), and remove the o-ring. Replace the cover and torque the bolts back down. Throught he intake ports, measure the clearance between the valve and the cover. It needs to be between 0.010" and 0.014". Anything above 0.014" will give you hard starting problems.

    If that looks ok, then I would rebuild your carbs.


    • #3
      I was having basically the same problem with mine getting started and you recommended (Bryan) that I turn IN an 1/8th. You tell Skinner to turn OUT an 1/8th.

      Can you explain what the difference is between turning IN and OUT. I would guess that turning in leans the mixture and out vice-versa.

      In that case, we would both probably need to turn OUT an 1/8th correct?


      • #4
        I believe YOUR problem was hard warm starting, which is typically over-rich, so you turn in.

        HIS problem is hard starting on the water cold, which is typically over-lean, so you turn out.


        • #5
          It seems like I have both cold and hot starting problems. It won't start when it's in COLD water. IF I can get it started after 10-15 minutes of crank'n, clean'n the plugs and fool'n with the throttle lever; even after I've run it for 30-40 minutes and it's HOT, I can't get it restarted. Wouldn't that point to "low voltage" CDI spark strength?

          BTW, the idle is set at 3000 on land and reads 1500 in the water. Also, I really did mean PWC's on my original post. I'm new, what can I say?


          • #6
            I would suspect the rotary valve cover codition/gap first.

            Sorry - when I read your first post - I read the 'RUNS GREAT' and my eyes missed the next part [img]graemlins/buck.gif[/img]


            • #7
              Thanks for the quick response. What's the next step if the RV is out of tolerance? Replace it?


              • #8
                It's the cover that would be out of spec, and you would need to get it remachined.


                • #9
                  Did I read that SBT offers a machined RVC exchange program for around $70? Do you still offer this service? What are the details? Thanks.


                  • #10
                    Yes, we offer them for $75 on exchange. All we need is the part number off the cover. If it's a 580/650/720 you must separate the cover from the manifold, and the part # is stamped on the cover front.


                    • #11

                      I checked the RV cover clearance and although it was between .012-.013, the surface of the cover appears scored like the surface of a record, also there is a wear ring about 1/2" wide around the shaft opening. Should it be replaced (P/N 6810 525)? Should I also replace the RV as well(159)?

                      On the engine side the surface appears smooth and unmarked, however there is a curving line scribed into the surface (which catches a finger nail) on the upper case half, which exactly matches the curve of the face of the rotary valve. It is located between the top left cover bolt hole and the timing mark (approx. 11:00 position). What do you make of this? Is it supposed to be there? Will it affect performance?

                      Thanks again for your help.


                      • #12
                        I would defnitely get the cover remachined, as the surface condition is very important to performance. It is not likely the source of your problem, however.

                        You only need to replace the actual valve if it's warped, chiped or dented in any way.

                        I wouldn't worry about a little scratch on your case. Although it's not desireable, it's not worth the trouble to get the cases remachined to fix it.

                        One thing we haven't verified yet, is your compression. Have you checked it?


                        • #13
                          Hi Bryan,

                          I've reassembled the engine with my SBT resurfaced rotary valve cover and rebuilt Mikuni carbs. According to my pop off tester the factory pop of settings were at 32 PSI. I have installed Ocean Pro flame arrestors and a primer kit (removed choke plate assemblies). From what I read in other posts, the pop off pressure with these mods should be in the neighborhood of 20-25PSI. Should I also change the needle/seat assembly from the stock 1.5 to a 2.0 and the 80gram spring, in order to adjust the carbs "rich" enough? Thanks again.


                          • #14
                            You don't need to change N&S, however you do need to change/clip your spring to lower your pop-off.

                            You will also need to alter your adjustment screw settings, if not rejet. Consult whatever shop sold you the flame arrestors for the correct settings.


                            • #15
                              Hi Brian,

                              I was out today doing the low & high speed carb adjusting, after setting my pop off pressure at 23PSI. I set the low speed jets at 1.5 turns out. I was working on the high speed settings at 1/4 turn out, when during WOT (approx. 6500 RPM) the engine rapidly lost power until it died and would not restart.

                              Back on shore, pressure testing showed the MAG cyc at 55psi and the PTO at 115psi. I pulled the head and found that the MAG piston must have impacted the cyc head. The perimeter edge of the piston head was worn down to just above the ring line. The center was untouched. Also the outer circumference of the cyc head where the piston edge hit was all beat up. (however the plugs finally had a nice chocolate brown color.)

                              What do you think happened? Will this require a COMPLETE engine rebuild or a least a rebuilt crank? Is the head salvageable?

                              Thanks once again for your help.