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Cannot accelerate past 50%, vibrations

k_dog345

New Member
Messages
7
Water Crafts
1996 seadoo spx
Hey guys,

New to the forum here. I recently replaced the carbon ring on my 1996 seadoo SPX. I noticed it was bad after I had it docked and it just about sunk on me (80% submerged), the area around the carbon ring was leaking badly. I had to pull the plugs and pump water out of the engine block when this happened. It ran fine after I had drained everything.

Last time I had it out, after replacing the carbon ring, it was running fine and no leakage. I hit a large wave, it seems that after this happened I started to experience issues. Throttle range from 0 to about 50% was OK. Past that, I could not get further acceleration and it would vibrate pretty badly. It felt like 'slippage' or something of that sort. I went ahead and pulled the pump again, checked the wear ring, seems OK, but I may not have the best eye for it. I checked the drive shaft, does not appear to have any damage. I also replaced the spark plugs just in case. Still no luck. Any ideas where to look? Should I just proceed with replacing the wear ring and see what happens?
 

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AKnarrowback

Active Member
Messages
535
Location
Fairbanks Alaska
Water Crafts
94 xp
94 sp
94 gtx
If the drive shaft looks straight I would put it back together, confirm you have rubber bumpers on both ends of the drive shaft, give a shot of grease on both shaft ends, then run it again. See how it runs.

It is pretty common to pull a small stick or solid object into the pump. The object can wrap around the leading edge of the impeller or wrap aroung the drive shaft and cause a horrible vibration and horrible performance. I have it happen almost on every ride. Most of the time you just shut the machine down, rock it back and forth or lift and drop the rear to " flush" out the pump, start it up and it runs fine. Sometimes you have to reach inside the intake with some mechanical fingers to clear things out.

The attached picture was a piece of heavy grass that took my gtx from a perfect runner to a vibrating monster that topped out around 10mph.
 

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POPPS

Active Member
Messages
405
Location
Grimsby Ontario
Water Crafts
96 XP 800 Limited Class
AK,has good advice, and before you install the pump, roll the shaft on a flat piece of glass, it could be out of true, The normal wear limit on the space between the prop and wear ring is 1 mm.
 

k_dog345

New Member
Messages
7
Water Crafts
1996 seadoo spx
I'd like to bump this thread, still experiencing the vibration after getting the jet re-installed. The shaft seems to be straight. Wear ring not too bad, but will attempt replacing it next. Is there any other possible reasons for the vibration and lack of power past 50% throttle?
 

gazzaskirepair

Active Member
Messages
548
Water Crafts
RXT. RXT IS SPEEDSTER 2006 REPAIR SEADOOS WEEKLY FOR CUSTOMERS
Your engine could be out of alignment
Also check your engine mountings for any damage the plate on top of mount sometimes separates from the rubber
 

POPPS

Active Member
Messages
405
Location
Grimsby Ontario
Water Crafts
96 XP 800 Limited Class
Okay, do you have the neoprene seal between the pump and the intake, if they are worn, you will definitely experience vibration.
 

k_dog345

New Member
Messages
7
Water Crafts
1996 seadoo spx
Thanks @gazzaskirepair I will check alignment.

I'm not sure @POPPS, I will check that when I get home

Could it also be possible that I overheated the new carbon ring assembly and need a new one? I realized I skipped over greasing the drive shaft when re-installing the first time. I guess the proper term of what I'm experiencing is cavatation (I'm a bit new to the jetski world)
 

POPPS

Active Member
Messages
405
Location
Grimsby Ontario
Water Crafts
96 XP 800 Limited Class
If the pump is good and the prop spins freely, then that should not cause a 50% lack in power. Does it rev freely on the trailer?
 

gazzaskirepair

Active Member
Messages
548
Water Crafts
RXT. RXT IS SPEEDSTER 2006 REPAIR SEADOOS WEEKLY FOR CUSTOMERS
Sounds like running on one cylinder
Pull the spark plugs and compare the two
Take a picture and post on here
 

k_dog345

New Member
Messages
7
Water Crafts
1996 seadoo spx
Well, maybe my drive shaft is not straight. I was inclined to see what would happen if I ran it without the propeller. Saw a lot of movement , and in the video you can see the shaft is not turning straight. Engine revs freely on the trailer. I guess all I need to do is replace my drive shaft then? Any other things I should consider replacing while I’m at it?
 

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Rapptorman

Member
Messages
14
Water Crafts
2001 GTS
1994 XP
The driveshaft will do that without the impeller installed to hold it in place. Aside from rolling it on a flat surface to verify it straight if you want to check it in the machine put the pump and everything back together and crawl underneath it while it’s running so you can see the shaft through the intake
 

gazzaskirepair

Active Member
Messages
548
Water Crafts
RXT. RXT IS SPEEDSTER 2006 REPAIR SEADOOS WEEKLY FOR CUSTOMERS
If you run it without the pump you’ll destroy the carbon seal and drive shaft splines + + +
Not a great thing to do
 

cocacola

Member
Messages
49
Location
Texas
Water Crafts
1997 SeaDoo GTI 720
1998 Lavey Craft Sebring 20.2 with 200 Mercury
did you ever find out what's wrong?
 

POPPS

Active Member
Messages
405
Location
Grimsby Ontario
Water Crafts
96 XP 800 Limited Class
Okay, never run the motor with just the drive shaft in, replace that neoprene seal, and make sure the shaft is true, it's possible that when you hit that wave, you did bend the drive shaft. Try rocking the engine from side to side,, bad alignment,from loose motor mounts or loose rear bracket will not give you a tight seal with carbon ring, and cause vibration.
 
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k_dog345

New Member
Messages
7
Water Crafts
1996 seadoo spx
Thank you all for the responses. Unfortunately, I have not yet got the ski running correctly yet. I have not had the time to work on it the last few weeks. But I can confirm that the engine is stable, and tight so I doubt it's an issue with the mounts.

I didn't realize I was making a mistake running the engine without the pump on! Yikes! Hopefully, no damage was caused.

I've also heard that if the accordian boot is not tightened properly around the carbon ring it could also cause cavitation?

I'm going to re-check the drive shaft, replace the neophrene seal, double check the accordian boot/carbon ring assembly. And verify that the teeth are OK on the drive shaft (they were on last inspection). I'll be sure to update here with any info.
 

k_dog345

New Member
Messages
7
Water Crafts
1996 seadoo spx
Also, @POPPS, there was only silicone where the neophrene seal should be. I didn't even bother replacing it. So maybe that's it? I'll order a new seal, and clean off the old silicon. Slap her back on and see how she runs. I hope it's as simple as that!
 

POPPS

Active Member
Messages
405
Location
Grimsby Ontario
Water Crafts
96 XP 800 Limited Class
Had a jet boat once, twin 720's, lots of vibration that the owner described. So, I went on a test run with the owner, and the vibration was nuts! I pulled the pumps, and both were missing the neoprene seals. Put in the seals, and what a happy customer he was, he chased that vibration all summer. Sometimes, it's something easy and cheap. And sometimes, the shaft protecters will cause ( some ), cavitation when they start to break, so I removed them.
 

etemplet

Premium Member
Premium Member
Messages
2,583
Location
Louisiana
Water Crafts
1996 SPI, 1996 GTX, 1997 GTX
Did you place a pry bar under the engine and try to lift it? I generally grab the engine by the exhaust and try to shake it. What you can do is remove the drive shaft and run the engine uncoupled. That would reveal and engine vibration issue if there is one.
 

IDoSeaDoo

Well-Known Member
Messages
3,018
Location
Davie, Florida
Water Crafts
1995 Sea Doo XP800 (future project)
2009 Yamaha FX HO
1997 Seadoo Challenger 4tec
Missing neoprene seal guarantees you're sucking air from outside the pump. This will cause massive cavitation which causes vibration. I'm 95% certain this is your issue. Seals are cheap, buy a spare when you order.
 

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