Can't pull a water skier?

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Manitoba_guy

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I'm pretty new to the PWC experience. I bought a used 02 gtx ltd. It a pretty great machine but the "hole shot" is terrible. I keep hitting the rev limiter trying to pull a water skier out of the water, just can't get him up. The top speed is pretty fast but the that's it. Looked at the wear ring and impeller and didn't see much damage other then nicks and scratches. Is the 155 just a big lazy seadoo? Maybe I need a better impeller? Any thought or opinions would be great!
 
It sounds like something is not working right, that ski shouldn't have much problem w/a skier. I have more experience w/the 2 strokes though...

learning key? normal key?
last oil change?
what's max RPM and top speed?
photos of impeller + ring?
 
how big is the skier? You should easily be able to pull out reasonable sized skiier's. I agree with Sabr, check the impeller wear ring...I had same problem on my 96 GTI
 
Myself and the skier are NOT light weights, I'm about 235lb he's about 220lb. The max rpm is 7500'ish. Oil is clean and full. I'll have a better look at the impeller and ring today and post pics.
 
My bro and I are the same, ill try to get him to pull me out today and see if it works, normally I pull the kids around
 
Ok so I had a good look at the impeller and wear ring. The ring looks perfect but the impeller looks like the previous owner was to cheap to replace it and took a grinder to it. It doesn't look bad other than the edges look rough.
 
Sounds like cavitation for sure. The wear ring only needs small knicks and it wont give you the pickup with a heavy load. You would be suprised really how small dings make a big impact. Take a pic of the ring and impeller and post it up.
 
To really understand how a Sea Doo works, you need to understand the basic propulsion concept. Think of your ski as a giant pump. The engine turns a drive shaft with an impeller. As the impeller turns it sucks water in through the intake on the bottom of the watercraft. The impeller is sitting inside the wear ring. It is almost a water tight fight. It should be very snug. As it sucks the water up, it pushes it out tha back side of the impeller. The water is forced through a smaller opening in the nozzle. Since the nozzle has a smaller opening, it creates thrust as the water is pushed out.

Anywhere along the way, if the water finds less resistance, it will escape there and in turn you will lose the amount of thrust out the nozzle. So if you have more space between the wear ring and the impeller, the water will be forced out around the imepller instead of pushed out the rear. That is what we refer to as cavitation. You need the same amount of water to go out the back as what comes in the intake.

Think of taking a straw and blowing as hard as you can. Now take the same straw and poke some holes in it and blow again. You get a lot less air out of the end now.....same concept. It only takes a slight leak to really affect your performance.
 
I once remember watching a discovery channel show about the design making for huge ship props. The computer simulations of poor designed props show bubbles destroying the prop, it was referred to as "cavitation". Maybe I'm wrong though. The definition Rfoster gave made toatal sense. I guess it won't hurt to change out the wear ring and impeller. Any ideas of what pitch, brand and web site to get an impeller from? I'd rather have acceleration rather than top speed.
 
You are correct about the air bubbles around a prop or impeller.The rough edge of an impeller will create turbulance.Air bubbles.On an outboard with an aluminium prop,and it is run at high trim at high revs,you will get pitting of the prop.Either at the tips of the blades or right up beside the hub.The air getting in there,will eat away at the aluminium prop.Skiis have stainlees steel props(impellars)
More air,less propulsion.Skiis have to first suck water into A chamber and then force it out another smaller chamber.At a higher speed than it came in.this is the propulsion.The rear nozzle and impellar size,dictate this.If there is a rough surface in these areas.Turbulance.Your impellar may be one.Because the impellar sucks water into the chamber,air may also leak through the shaft seal if it's faulty.Check these things and also what the guys say on this site.the info you get here,you can't buy.
 
I once remember watching a discovery channel show about the design making for huge ship props. The computer simulations of poor designed props show bubbles destroying the prop, it was referred to as "cavitation". Maybe I'm wrong though. The definition Rfoster gave made toatal sense. I guess it won't hurt to change out the wear ring and impeller. Any ideas of what pitch, brand and web site to get an impeller from? I'd rather have acceleration rather than top speed.


Same concept. Air being introduced is the problem. I am a firefighter and engineer on an engine. A fire truck pump works the same way. If we have it attached to a fire hydrant that is only capable of say 1000 gallons of water per minute and we are trying to flow 1500 gallons per minute, the pump with suck air. We call that cavitation. You cant try to push more out than what is coming in.
 
ok here is some pic of my impeller n ring...
 

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lousy pics...sorry...shoulda pulled the pump first. Just looking though at the pics...the gap between the prop and ring look to be too great. if he ground the prop...he may have done the sides as well as the leading edge.

Dave at Impros will fix you up.

Picture a 60-70's muscle car lighting up the rear wheels at a stop light. Our props spinning w/o pushing water is what we experience as cavitation. Motor revs up but thrust is lagging...especialy on hard take offs...like what's needed to pull a skier outa the water.
 
yeah the ring looks good form the pics but that gap is too big. I would get a new or refurbished impeller and you should be good to go.
 
First,,, your ski under normal circumstances is PLENTY strong enough to pull a ski'er.
Second, the impeller looks pretty ruff, though the leading edges (even as ugly as they are) are not a real issues, I also think the gap is too big.
Third,,, even if you were not getting cavitaion in the traditional sense, you are losing much of the "power" aspect of the ski as the water is slipping by the impeller, not going through the impeller and tube as a unit.
I would look into seeing what impeller is in there now and see if it is in fact compatible to the OEM impeller.
The wear ring itself is pretty cheap, if you are going to replace the impeller, (which I think you MUST in order to solve your issue), you might as well do the wear ring at the same time.

I am betting you will think you have a new ski when you hit the water...
 
Great thanks everyone for your help. I think I'm gonna take it to the stealership and have them replace it. I'm pretty mechanically inclined but I'm know nothing about these machines. Do you guys think it will cost me more than 500$ for a new impeller and ring + labor?
 
Yes, that's why they are called "stealerships". I wouldn't be afraid to try it myself when the time comes.
 
There are many posts on doing the job here at the forum. I am on my phone right now so it is not easy for me to do a search for you. There is also a section of "How To" do things, I would be shocked if the details are not there...
 
The prop removal tool...between $16-$35...depending...a vice...a 12mm(i think) allen wrench and some sockets and smaller allen wrenchs...I can pull the pump swap the prop grease the cone and replace in under an hr.

Use the freezer method when replacing your wear ring.
 
there looks to be a 1/8 inch gap between the impellar and ring. Cant be sure cause the picture quality. But to me it seems like the previous owner dingged up his impellar pretty good and grinded the dents out thus losing your full diameter. the ring looks good from those pics.
 
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