New Impeller & Wear Ring But Still Feels Like Its Cavitating (Slow Launch, Limiter)

[ENRKyle20]

SO I recently bought a 94 SeaDoo SP 600 (580cc). The ski runs GREAT but since I bought it it has had a hard time getting going. You hit the throttle and it revs up fast and hits the rev limiter. If you keep on the throttle it will take about 5-8 seconds slowly accelerating then once your on top of the water you will hear the RPM drop off the rev limiter and the ski will pull forward strong. Its like its sucking in air until its on a plain. It actually accelerates A LOT faster if your gently on the throttle - Once it starts feeling/hearing like its "slipping" let off a little and it "grabs" again. Doing this you can get it on a plain in 3 seconds or so but nothing compared to my Yamaha (Hit the throttle and it grabs and front end comes up and your off instantly)


What else could it be? Like I said the impeller is new and so it the wear ring. The clearances are perfect between the impeller and wear ring. It feels EXACTLY how it did before the new impeller and ring but the old impeller was in fairly bad shape. I was quite disappointed to have spent all that time and money on the project to have it make no difference. I DID use silicone where the impeller housing bolts up to the hull. Is there anything else I need to be sure seals?

Thank you in advance for any help :-)

[ENRKyle20]

Re: New Impeller & Wear Ring But Still Feels Like Its Cavitating (Slow Launch, Limite

So a good amount of searching and this is what I come up with. Are all / any of these relevant to this machine?

It has to be the pump sucking in air somewhere not cavitation since its a new impeller and wear ring correct?

SO Other places it can suck in air to make it feel this way:


1) Drive shaft Seal - Sucking air from inside the craft when under hard acceleration. (Is this just a bearing or is there a actual seal there to replace?)
2) Ride Plate / Ride Shoe Seal - Sucking air from side of the ride plate / shoe? Seems unlikely since its completely under water when taking off (Should there be a gasket or any sealant between the plate and the hull?)
3) Pump to Hull Seal - Sucking air from the point where the pump bolts to the outside of the craft, tho this was sealed, it may not have been sealed well enough.



If that is the only other thing, is there a way at all to narrow it down or should I address them all?


Thank You

[dsolie]

Re: New Impeller & Wear Ring But Still Feels Like Its Cavitating (Slow Launch, Limite

1,2 & 3 are all the places it can happen. #1 is the most common, check for loose clamps. There is a bearing, and one that should be greased often. #2, ride plate is easy, if it's the shoe, light the ski on fire and walk away, there are no gaskets, just sealant... #3, another common area, use sealant...

[ENRKyle20]

Re: New Impeller & Wear Ring But Still Feels Like Its Cavitating (Slow Launch, Limite

ok. I will take a look at all of those areas. Im not 100% sure what the shoe is tho.

Thank you for the response

[dsolie]

Re: New Impeller & Wear Ring But Still Feels Like Its Cavitating (Slow Launch, Limite

The shoe is the ramp that feeds into the pump. It's also where the pump mounts to the hull.

[ENRKyle20]

Re: New Impeller & Wear Ring But Still Feels Like Its Cavitating (Slow Launch, Limite

ohh ok, So if this was the problem it would requre fiberglass work to fix. Is this somehting that I would see when with the intake grate off and or the pump off (Physical cracks)?


ty

[dsolie]

Re: New Impeller & Wear Ring But Still Feels Like Its Cavitating (Slow Launch, Limite

The pump shoe is held in place by some serious sealant. Removal of the pump shoe usually ends up in destruction of the hull...

99.9% of the time the shoe is not the issue. Apply sealant, marine grade caulking to all seams. Rideplate area, intake grate area, pumpshoe to hull area and re-seal the pump to shoe area. Also, grease the carrier bearing and make sure the clamps are tight.

[ENRKyle20]

Re: New Impeller & Wear Ring But Still Feels Like Its Cavitating (Slow Launch, Limite

Very good. Thank you for that description. I will defiantly be doing that!

One last question, and I know its in the wrong forum, but I just rebuild my 95 Wave Venture 700 and its doing the SAME exact thing. Now on this one I did not replace the impeller or wear ring but I did check it out and measure the clearance and its not bad and the impeller looks almost perfect. Is it going to be the same procedure on this machine?

Also, whats considered high hours on a ski? can we compare it to miles on a car, like 500 hours is equivalent to 50,000 miles in terms of wear and how long a machine should last or something.. ect. Thanks

[dsolie]

Re: New Impeller & Wear Ring But Still Feels Like Its Cavitating (Slow Launch, Limite

The WV couldn't hurt from some extra sealant.. Worth a shot...

There is no comparison to hrs vs miles. It's all about maintenance. Salt water vs. fresh water does make a difference though.. Typically, salt water machines are tougher to work on because the bolts will be corroded and will break when you try and work on the ski.

[ENRKyle20]

Re: New Impeller & Wear Ring But Still Feels Like Its Cavitating (Slow Launch, Limite

So i didn't have a lot of time to do all those steps before the family get together at the lake Sunday. Time is a little hard to come by. I did check the hose clamps on the rubber boot over the shaft. I don't know exactly if that is where it would leak but from the bottom its just a rubber coated hole in the hull that the shaft goes threw (is that normal?). So I did tighten those clamps but it did not help any.

BUT noticed something that may help. First the more weight on the machine the worse it is and the longer it takes to get on a plain.

The second (more significant) discovery is that if you turn the craft slightly (so it leans) it takes off flawlessly. Any ideas?.. lol.

Actually almost any time you turn it does not feel like it cavitates, you can go in circles at WOT and its fine 98% of the time.


Does this mean that its most likely the ride plate? its leaking air from the forward most point where it meets the hull , and it should be removed and sealed?.

Thank You

[dsolie]

Re: New Impeller & Wear Ring But Still Feels Like Its Cavitating (Slow Launch, Limite

Couldn't hurt.. Also, take this to heart.. Those older ski's were not the best design as far as pump flow... They have gotten a lot better over the years. I used to own on old 580 and she would cavitate as well (6' 240lbs).. My wife hopped on it and it wouldn't.. Could just be the nature of the ski...

Yes, that rubber boot where the driveshaft goes through is the clamps you are supposed to tighten.

[ENRKyle20]

Re: New Impeller & Wear Ring But Still Feels Like Its Cavitating (Slow Launch, Limite

ok glad I got the right clamps. That seals well. And I understand that older skis are not the best, I guess since my older VXR PRO gets right up and goes I assumed they all should but It could very well be the nature of the beast. I will seal the ride plate and hope it help, if not - no huge deal.. Its my girlfriends ride anyway I just wanted it to be perfect.

Thank you all for the suggestions and the help its greatly appreciated!