650/X-2 1990 superjet throttle problems

[Will S]

Hello all. I am having some issues that I can't figure out.

The problem I'm having is after my ski is started, it idle's just fine. When i go to give it gas, I hear the engine revving up, but the impeller is not spinning any faster than when its just idling. Every once in a while, it will go past idle when i give it gas, It will continue normal for about 5-10 seconds before the engine just rev's again and the impeller goes back to idle, even though the engine is still revving high.

I have taken the pump/driveshaft out. The splines and the drive shaft are just fine and the impeller is not stripped. I'm guessing this is something stripped inside the engine?

Any help or guidance would be greatly appreciated!! Thanks!

 

[Tyler Zane]

You say you checked the splines but that's about all it could be. Pull the coupler cover and take a peek at that area.

Have you ran it in the water?

There isn't anything to "strip out" in the engine..

 

[Will S]

You say you checked the splines but that's about all it could be. Pull the coupler cover and take a peek at that area.

Have you ran it in the water?

There isn't anything to "strip out" in the engine..

Yeah, the splines were almost perfect, no signs of wear. I pulled the coupler cover off, (it was just that plastic piece) and did not notice anything out of place.

Yes, This is all information from when i've been using it in the water.

Could it be the flywheel?

 

[Tyler Zane]

If it runs OK it's not the flywheel. A sheered flywheel key will cause some crazy symptoms and irattitic running issues if it will run at all.

Sounds like the wear ring to impeller clearance is way to far gone and its making it sound like something is "stripped out". When in reality its just not producing thrust but just spinning water like a blender. The pump has to be forced to pull water and push water by not having any other choice but to push it out the reduction nozzle. If the wear ring is shot it blows the impeller out rather than actually producing thrust. A damaged impeller can cause this too as well as too little pitch.

 

[Will S]

If it runs OK it's not the flywheel. A sheered flywheel key will cause some crazy symptoms and irattitic running issues if it will run at all.

Sounds like the wear ring to impeller clearance is way to far gone and it sounds like something is "stripped out".

Thanks for the quick replies. I am going to disassemble the pump again, and take some pictures. The wear ring does not really show any damage and the clearance and looks fine to me.

I am also going to run it out of the water and see if the coupler speeds up when I give it throttle. If it does, then i know if has to be something with the driveshaft or impeller.

Ill keep you posted. Thanks,

 

[Tyler Zane]

Your welcome and I'm glad to help.

Wear rings are wearable items (no pun intended). I'd be more surprised if a 1990 didn't need a wear ring and impeller.

 

[Will S]

Your welcome and I'm glad to help.

Wear rings are wearable items (no pun intended). I'd be more surprised if a 1990 didn't need a wear ring and impeller.

Sorry, if this sound dumb, I have not really worked on these before.

I googled wear ring, and kinda understand what it is. When i took apart my pump, I don't recall even seeing the wear ring in the housing? The gap between the impeller and the housing was kinda big. like 1/8 to 1/16 of a inch.

Does this mean that I might have lost the wear ring completely, and that is causing this issue?

 

[Tyler Zane]

No need to apologize. I'd rather someone admit they are new and in experienced than pretend like an expert. I learn new things everyday. And we have all been where your at.

The wear ring is the plastic or stainless steel housing around the impeller. Its like a shroud on a fan. It forces the impeller to pull and push rather than blow outwards. Per the superjet manual impeller to wear ring clearance should not exceed .02 inch or .4 mm. I figure your guessing at the gap because of the range you gave.

Now let's talk more about wear rings. If its plastic, then the wear ring is the wearable item. Some skis came with a stainless steel wear ring and in that case the impeller typically is the wearable item. It could have either because it's most likely been changed at least once.

Plastic is preferred by those that ride sandy conditions because you can change the lwear ring liner out yearly for 30 bucks. People who don't ride in sandy conditions normally prefer stainless because it last a long time. The problem with stainless is salt water can cause it to swell and sieze up the impeller.

Even if the impeller to wear ring clearance is fine, the impeller could be damaged to a point that it doesn't work effectively. It would have to be pretty messed up to do what you describing though.

You could also be sucking air from the pump cavity or bilge also.. There is a seal in front of the pump that seals against the pump shoe. If this is damaged or missing it would have a similar issue to your description. Your midshaft is to be sealed as well so the impeller can't pull air from the bilge.

I know this is a ton of info. Please ask questions if you need explanation on anything.

 

[Tyler Zane]

Also id like to welcome you to the X! I just noticed This is your first thread. There is tons of info in the tech FAQ, I advise you to read them all. There is also a search function thats helpful and we appreciate newcomers to use it but we also dont want you to hesitate to ask questions. Thats why we are all here... to learn and converse.

I hope we can get your ski diagnosed soon so you can worry about gas instead of wrenches.

If you do decide to go further with your project id like to introduce you to the one stop shop with great prices, @JetManiac. http://www.x-h2o.com/index.php?thre...new-used-yamaha-and-custom-build-parts.85372/

 

[Will S]

I was able to work on my ski this past weekend. Thanks to your help, I found that the seal between the pump and the hull was worn. I was able to save the seal by super gluing back into place on the pump. That seemed to work without having to by a $30 seal. It looks like the clearance between the impeller and the wear ring was still in good shape.

Thanks for the advise.

 

[Tyler Zane]

lmao, you used super glue? it aint dumb if it works but I would of just replaced it so I didn't have issues in the future. If a pump seal is too much then your in the wrong hobby.