This seadoo is one problem to the next. 97 GTX 787

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motoXman

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I've decided to start a new thread because my problems no longer relate to carb issues and the thread is dead. I need this running and out of my shop.

In the compartment up front with the computer and regulator/rectifier there is a blown out 15 amp fuse. I replaced the fuse and soon as I plug back in the rectifier the fuse blows again. Bad rectifier right? Well the machine is shut off and blows the 15amp fuse. I don't think the rectifier does anything until the engine is running. A battery alone won't pop that fuse on the back side of the rectifier. Anyone run into this before? I'm thinking there has to be a dead short in the harness... But I can't find anything.


Last but not least, with that fuse fuse blown out will that cause the engine to not perform past half throttle? It accelerates up to 5500 rpm and does nothing more. No bog, no sputter just sits there at 5500. Carbs Are good. Fuel supply is verified, raves are clean.


Here's the old thread for those following along http://www.seadooforum.com/showthread.php?63975-Carb-issue-1997-seadoo-787

Thanks
 
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that 15 amp fuse blowing could be a bad rectifier or a stator coil that has shorted out. as long as the battery is good and charged, having the rectifier not charging shouldn't affect running.
 
Thanks for the fast reply. I should also note of all the fuses only the one 15 amp in the box up front blows, all the others are ok. I read about bad stators shorting out from the starter.. In those cases all fuses were blowing which I'm hoping leads me away from that problem. So that being said, I'm yet to see a bad rectifier cause a fuse to blow with the engine off... Anyone ever find different?

If there is a dead short to ground and not caused by the stator, Where might I look? The harness is clean. Arrgg

Thanks
 
yes, and i believe that when the stator is shorted it blows only when you first start the engine due to shavings off the starter bendix. i'd ohm the connectors to the stator to make sure they're in spec. if they are, i'd replace the rectifier and see if it fixes the fuse blowing issue.
 
A blown fuse in the charging circuit is most likely IMO due to a shorted diode in the rectifier. Also, connecting the battery backwards will cause this, and damage the rectifier.

If the rectifier is good, no current can flow in reverse from the battery into the stator, only out of stator through rectifier as it should be. If the rectifier is shorted then battery current will flow into stator through the rectifier and hopefully the charging fuse will blow before the stator windings insulation is burned.

Sometimes stators can corrode due to water trapped in the stator housing.

I don't know how a bad stator can damage the rectifier though, can't think of how that could be possible. I can see how the stator can be physically damaged by lose parts stuck to the flywheel magnets or possibly the stator can be damaged by a shorted rectifier if a fuse too large is installed by mistake in the charging circuit.
 
"I'm yet to see a bad rectifier cause a fuse to blow with the engine off... Anyone ever find different?"

Yes, if the rectifier is shorted current will flow backwards through the rectifier into the stator.

"If there is a dead short to ground and not caused by the stator, Where might I look?"

The rectifier most likely has a shorted diode, IMO. Check stator winding resistance before replacing rectifier b/c it's possible both may be damaged. If the charging fuse blows, in my experience it's almost always due to a shorted rectifier. If the stator is damaged, then it could be due to a shorted rectifier unless the damage was caused by physical damage such as corrosion or lose parts stuck to the flywheel.
 
Have you checked for a short to ground? It sounds like something is completing the circuit past the rectifier / causing the fuse to pop (IE you're completing the circuit when you connect the rectifier)

What completes the circuit for the rectifier to power... I don't have a wiring diagram - Is it power or ground side switched?

If it's power side, the short would be between the rectifier and the fuse, but I'm thinking ground side switched as you're not getting smoke with the rectifier disconnected..

Try checking for a short to power or ground on either side of the connector for rectifier..
 
Thx guys. Btw I'm not a repair shop, this is my brother inlaws machine... I'm helping him solve his 2 year battle with this thing. I'm currently looking for a clean XP for myself. Again thx for all the tips
 
Yeah honestly I don't see why there's a 15 Amp fuse in these crarging curcuits when supposedly they aren't capable of more than 10 Amps I've been considering installing a 10A fuse in mine just to protect the regulator in case of something weird happening, a 10A fuse seems safer but then again maybe running with no load if the fuse were to blow would be harder on the regulator b/c it would have to shunt all the excess that ordinarily would be absorbed by the boat.

I'm not sure yet which is the weakest part of the RR, if it's the shunt regulator or the rectifier diode section. This may even vary from regulator to regulator, some are just 2-wire single phase and others are three-wire three-phase.

I've also been considering installing a separate regulator in my boat instead of the MPEM internal regulator, would hate to see the internal regulator take down my entire MPEM, whew, that design makes me nervous.
 
I've read on these PWC forums that a bad VTS can blow fuses. Assuming yours is bad, try disconnecting its wiring and see if that stops the fuse blowing. Both of my 96 XPs have non-working VTS systems but neither ski blows any fuses.

Bad rectifiers will cause low WOT RPM. I don't know if blown fuses will or not.
 
Sportster-2001-951C-Stock said:
Yeah honestly I don't see why there's a 15 Amp fuse in these crarging curcuits when supposedly they aren't capable of more than 10 Amps I've been considering installing a 10A fuse in mine just to protect the regulator in case of something weird happening, a 10A fuse seems safer but then again maybe running with no load if the fuse were to blow would be harder on the regulator b/c it would have to shunt all the excess that ordinarily would be absorbed by the boat.

I'm not sure yet which is the weakest part of the RR, if it's the shunt regulator or the rectifier diode section. This may even vary from regulator to regulator, some are just 2-wire single phase and others are three-wire three-phase.

I've also been considering installing a separate regulator in my boat instead of the MPEM internal regulator, would hate to see the internal regulator take down my entire MPEM, whew, that design makes me nervous.
Click to expand...

the charging system can't produce more than 10A, but if you short to ground the battery can send a lot more than that through it. the fuse is there based on the rated amperage of the wiring connected to it. Its purpose is to burn instead of some printed circuit in the MPEM.

[MENTION=66128]dannyual767[/MENTION] - there's no VTS on this GTX
 
I'm pretty sure that most people will highly recommend that you buy a genuine Sea Doo rectifier and not an aftermarket unit. Just sayin'.
 
For those still following the thread here's an update


I just found a closed circuit (ground). On the 6 pin connector on the engine going to the stator there is a full out ground between 2 of the yellow wires and the engine ground or block. From what I've read this is supposed to always be open circuit. I'm going to go ahead and attempt to pull the stator with the engine still in the machine...... Arggg
 
Yep, the dreaded stator short to ground. A short to ground on a yellow stator wire is cause for concern and a good reason to consider pulling the stator cover. I hope to never see this on my 951 engine.

Good luck, hope it's easy enough to get to.
 
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Problem solved?!? Drumroll please...


298.jpg




299.jpg
 
^^ Aw, you make it sound like that's bad.. lol. Those loose bolts just serve as counterweights..

Nice find though. Your bro in law owes you a few cases of good beer. Tell him we all think so.

I'd try and find good used parts. Minnetonka4me might have what you need.
 
Strizzo said:
the charging system can't produce more than 10A, but if you short to ground the battery can send a lot more than that through it. the fuse is there based on the rated amperage of the wiring connected to it. Its purpose is to burn instead of some printed circuit in the MPEM.

[MENTION=66128]dannyual767[/MENTION] - there's no VTS on this GTX
Click to expand...

Of course the purpose(and location) of the fuse selection is to avoid damaging components such as wiring, I guess my question is along the lines of "what if...." , say the battery was connected in reverse does the fuse blow before the rectifier diodes fry, or after they fry? If the fuse capacity is 15A then certainly that would be exceeded by attempting to convert the boat into a "chick magnet" by reversing the battery polarity? ;)
 
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