DESS issue 96 GTX 787

Ardilla

Ardilla

Active Member
Hi,

I rebuild the carbs of my 787 96 GTX with Mikuni kits included needles. Now throttle response is good with no issues or any strange hesitation and starting is fine. Fuel line is directly connected to full buttle on reserve to avoid any issue from this side. Ski is stock. I also cleaned the RAVE valve and water regulator.

The problem is that the ski has no power, I can push throttle WOT but ski is not accelerating and has no power. Max rpm once starting are 6800-7000 rpms but ski is not moving strongly. Max speed is really low and it take a lot to take off.

I check the wearing and impeller as I change it couples if year ago and they both look totally new. I moved the drive shaft manually, but it is totally free and moving smoothly.

Thanks for the support as I do not know where to go now… Engine can be wrong? reaching max RPMs?

Thank for help
Frederic
 
Ardilla said:
Hi,

I rebuild the carbs of my 787 96 GTX with Mikuni kits included needles. Now throttle response is good with no issues or any strange hesitation and starting is fine. Fuel line is directly connected to full buttle on reserve to avoid any issue from this side. Ski is stock. I also cleaned the RAVE valve and water regulator.

The problem is that the ski has no power, I can push throttle WOT but ski is not accelerating and has no power. Max rpm once starting are 6800-7000 rpms but ski is not moving strongly. Max speed is really low and it take a lot to take off.

I check the wearing and impeller as I change it couples if year ago and they both look totally new. I moved the drive shaft manually, but it is totally free and moving smoothly.

Thanks for the support as I do not know where to go now… Engine can be wrong? reaching max RPMs?

Thank for help
Frederic
Click to expand...
Rpms are good, check the clearance between your impeller and wear ring., specs and procedure is in the manual. If that checks out, perhaps a worn driveshaft
 
Thanks

Clearance between impeller and wear ring is good.

What do you mean with worn driveshaft? i have no noise or anything strange. How it can be and went wrong? anyway to check it?

Thanks again
 
Also could be sucking air into jetpump causing cavitation. Check the condition of the carbon ringl and stainless steel hat. Could also suck air if the ride plate and shoe are not sealed to the hull properly.
 
If you are seeing 6800-7000 rpm and the ski isn't acceleration then it is a pump/driveline issue.
90% of the time it is a bad wear ring.
5% Impeller
4% neoprene seal
1% driveshaft.
Or some percentage like that :D.

Pull the pump and you should find your issue.
 
I checked again the impeller, wear ring and all ok. I checked again drive shaft and moved with the hand and look fully free.
Carbon seal looks also good so I do not understand or see from where cavitation is coming.
 
Ardilla said:
I checked again the impeller, wear ring and all ok. I checked again drive shaft and moved with the hand and look fully free.
Carbon seal looks also good so I do not understand or see from where cavitation is coming.
Click to expand...
Did you check impeller to wear ring clearance with feeler gauge or just visually? Maybe measure and see what you have, to have proper rpms and not moving, there’s not much else
 
The ride plates on the 96 and 97 GTXs were known to leak air. Pull the pump AND remove the ride plate.You may be surprised how easily it will fall off. Clean and reseal with good silicone and see if that vastly improves your problem.
 
Thanks for the info I Will have a look if problem is not fix. I replaced Carbon seal and need to test be jet.
 
jchance said:
The ride plates on the 96 and 97 GTXs were known to leak air. Pull the pump AND remove the ride plate.You may be surprised how easily it will fall off. Clean and reseal with good silicone and see if that vastly improves your problem.
Click to expand...
Just trying to pick your brain, not second guessing you cause I’ve seen this response before but how does the ride plate not being sealed good cause cavitation due to sucking the air? Is the ride plate not beneath the water
 
Take a good look at it. The leading edge of the plate actually rides right at the water/air interface. If it leaks then it will suck air and cavitate. I didn’t believe it either until I had to reseal all 3 of my GTXs. Go to PWCToday.com and search for my posts with Bill O’neal at Watercraft Magic. He is who told me about it and it really does occur. If you remove all of the bolts and it falls off pretty easily then you will see. The mastic used in ‘96 and ‘97 just didn’t last. If it doesn’t budge then you are probably good.
 
jchance said:
Take a good look at it. The leading edge of the plate actually rides right at the water/air interface. If it leaks then it will suck air and cavitate. I didn’t believe it either until I had to reseal all 3 of my GTXs. Go to PWCToday.com and search for my posts with Bill O’neal at Watercraft Magic. He is who told me about it and it really does occur. If you remove all of the bolts and it falls off pretty easily then you will see. The mastic used in ‘96 and ‘97 just didn’t last. If it doesn’t budge then you are probably good.
Click to expand...
It’s not that I didn’t believe you, the ride plate is the piece right at the back beneath the pump/Venturi? Is that right? It’s not the intake grate is it?
 
Not the intake grate that covers the impeller. I’m talking about the entire metal plate on the bottom of the Seadoo.
 
Check impeller for pitting from cavitation, and that blades are not damaged or bent, and wear ring for gouges or signs of wear that's not uniform. If impeller shaft bearings are a little loose, the wear ring will wear unevenly and the seal will leak, and you may find water in the nosecone instead of oil.
 
i checked impeller and it is perfect also wear ring is untouched
impeller is rotating properly with the hand.
i changed the carbon ring and gasket but... my DESS key is not working anymore a non ending story...
 
I have now issue with DESS and cannot use the jet.

When i press the start button without the key i have the long bip, je is asking for key as it is missing.
When i connect the DESS KEY no signal no sounds, like nothing.
When i connect the key to another ski, key is reconise but i can't start that ski.
When i connect multiples times the key on my ski, after many fails i have sometimes the double beep and i can start the jet. this happens perhaps 1 out of 30.
i have also another key for this sky and same issue
I cleaned the connector from the battery and battery is fully charge.

What is the issue? it is the MPEM or the connector from the DESS? how i can test it or know from there issue is coming from.
is there any other part to check the fuse or connections

thank for the support i am going crazy with my 96 gtx
 
DESS post failures are not uncommon. Probably not the MPEM. Swapping posts while making sure all of the connections are tight and clean may be your only option unless you have access to a programmer like a Candoo Pro or Seadoo programmer.

I doubt your issue is a bad chirper but they are also known to go out. If you plug the key onto the post and it will crank without the beeps then it could be the chirp instead. That problem can be intermittent.
 
M
Ardilla said:
I have now issue with DESS and cannot use the jet.

When i press the start button without the key i have the long bip, je is asking for key as it is missing.
When i connect the DESS KEY no signal no sounds, like nothing.
When i connect the key to another ski, key is reconise but i can't start that ski.
When i connect multiples times the key on my ski, after many fails i have sometimes the double beep and i can start the jet. this happens perhaps 1 out of 30.
i have also another key for this sky and same issue
I cleaned the connector from the battery and battery is fully charge.

What is the issue? it is the MPEM or the connector from the DESS? how i can test it or know from there issue is coming from.
is there any other part to check the fuse or connections

thank for the support i am going crazy with my 96 gtx
Click to expand...
My bet it is you dess post
 
jchance said:
DESS post failures are not uncommon. Probably not the MPEM. Swapping posts while making sure all of the connections are tight and clean may be your only option unless you have access to a programmer like a Candoo Pro or Seadoo programmer.

I doubt your issue is a bad chirper but they are also known to go out. If you plug the key onto the post and it will crank without the beeps then it could be the chirp instead. That problem can be intermittent.
Click to expand...
ok thank you!
I checked the connections of the post but all looks ok on this part. honestly it happens from time to time that i had to add water to the key to start in the past.
i will try to swap de DESS post from another ski and try it this way.

thanks
 
Hi,

I connected the key on my gtx 96 with another DESS post that is working 100% on my 99 spx. Ski is not starting every time but i can start it 1 of 8.

On the other hand it happens that I can start the ski without the double beep. Sometime there is the double bip and works normally, sometime double beep is interrupt with the long beep (i cannot start the ski), many times i have not double beep (it happens that i can start it without double beep 25% of the time in this case).

What are the next steps?? Is the MPEM having an issue? any fuse to check? or any additional wire?

thanks for the support i do not want to look for MPEM with Key that are here very expensive (more than the ski)

thanks again
 
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