Super Jet Thrust issues...

So my buddy and I were riding last Saturday when he said his ski lost all power and the engine start hitting a much higher pitch (noise) than normal. He said he sounded similar to when he threw a belt on his car for what that's worth. We towed it back to shore and I took a look at the insides and everything appeared to be connected and in good condition. When i started it there holding it I could hear what he was talking about. Much higher pitch like high rev noise but didn't have the brap sound. Didn't sound good.

The engine was also very hot to the touch. I let it cool down a bit and started it again and ran it for about 10 seconds and was not able to get any water to come out the pisser. As all the lines were hooked up I thought this might be a pump issue.

I let it cool down again and put it into deeper water and was prepared to get yanked off my feet. I started it up again and the engine sounded about normal this time. However, the ski went no where, I revved it pretty high and was able to hold it just fine, there was some water getting pushed out through the prop but not enough to move the ski while i was holding it.

This made me think again that it was the pump. So tonight I pulled the pump out hoping to see a broken/stripped driveshaft or broken impeller and from what I can see the drive shaft, impeller are all in good working order. I then checked the midshaft and from what I can see without pulling it all apart they are hooked up and when i turn over the motor it spins just fine.

At this point I am at a loss for what it could be. The engine sounded fine out of the water in my garage and it spun the midshaft fine. Could it still be stripped and it only freespins under load? If the midshaft is spinning fine and motor running fine now the crank etc should be ok?

We recently replaced the head gasket on this ski, has maybe 2 rides on it since. I don't see how that could be connected but I figure the more info you guys have the better.

The ski is a '92 SN with a stock motor, a/m electronics, and Bpipe.


I was about to take the motor out and disassemble it all to take a look at the crank and take a closer look at the midshaft but I figured I would ask you guys before I did all that work.

Appreciate any input you guys can offer.

Thanks!
 
Sounds like it could be the seal between your pump and pump shoe is bad. Causeing cavitation maybe

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Last edited:

DarkWater

Down Side Up
Location
waterford, MI
So the coupler on the motor is spinning fine.
The drive shaft, impeller and pump look OK.

That leaves the splines in the mid shaft, did you pull the mid shaft to examine?

Did you remove the impeller? It might be stripped but you might not be able to spin it like the motor can.
 
Heres some pics of the drive shaft splines. They look a little funky to me but I have never seen any up close before to know if they should look like this. Whats the verdict?

2012-06-21_19-59-28_7.jpg


2012-06-21_19-59-16_869.jpg


2012-06-21_19-59-01_572.jpg


2012-06-21_19-58-51_165.jpg
 

DarkWater

Down Side Up
Location
waterford, MI
That is stripped my friend.
Here is a good shaft next to a stripped
uploadfromtaptalk1340336013560.jpg

The splines should be even all the way, not 2 stage like our stripper here.
 

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Fantastic...well at least I know what the issue is! Thanks for your help sir!


In your opinion would it be better to buy just a new shaft or a whole new pump setup? I have heard it is a absolute bitch to get impellers off drive shafts.

Annnnnnd is the midshaft safe to use or is it probably stripped out a bit too from the shaft spinning inside it?
 
Last edited:

DarkWater

Down Side Up
Location
waterford, MI
Hey no problem! I help as i can!

I have had a few nightmare pumps and a few that weren't so bad.
You can buy an entire pump these days for pretty cheap. Many people are buying AM, and with the solas "MAG" stator out now, more people have oem pumps laying around.

I would try to remove the impeller either way, that's $$ that shouldn't be thrown away!!
Its tough to say with the midshaft, you need to examine it carefully.
If its in the budget, it should probably be on the shopping list.

Glad to help. Wish you luck!
 
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