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Rough idle on 1999 GSX RFI 787

changetires

Active Member
Messages
42
Location
Mobile Alabama
Water Crafts
1999 GSX RFI
1999 GTX Limited
What would cause a rough idle on this ski. I cleaned the fuel rail and the injectors. Also cleaned off the RAVE valves. Installed new plugs and gapped them at .020. Checked the voltage at 5500 rpm and was reading 13v. This is also on fresh gas and oil?

Tks
 

mikidymac

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The RFI skis can have a rough idle because they only idle on one sparkplug. I thought something was wrong on the first one I ever rode because it ran perfectly but idled rough. Once I found out about the single cylinder at idle I got over it and all the other ones I have been on did the same thing.
 

mikidymac

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No clue but I would think so.
 

changetires

Active Member
Messages
42
Location
Mobile Alabama
Water Crafts
1999 GSX RFI
1999 GTX Limited
Where can I get a new diaphragm for said RAVE Valve. Ski was doing 6200 rpm the other day and all of a sudden it dropped to 4900. You can give it more throttle but it acts like it goes into limp mode when you do. Had the seat off today running on the hose and noticed copious amounts of water coming from the piss hole out the bottom of the valve
 

mikidymac

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2001 Superjet
Directly from Seadoo.

420260721
Bellows
MSRP: $40.99
Dealer Price: $40.99
 

etemplet

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Messages
3,203
Location
Louisiana
Water Crafts
1996 SPI, 1996 GTX, 1997 GTX
Where can I get a new diaphragm for said RAVE Valve. Ski was doing 6200 rpm the other day and all of a sudden it dropped to 4900. You can give it more throttle but it acts like it goes into limp mode when you do. Had the seat off today running on the hose and noticed copious amounts of water coming from the piss hole out the bottom of the valve
A leaking diaphragm will cause a loss of RPM in the top of the range. I don't see where it could affect the bottom of the range at all but.... I'm no guru. LOL I'd check fuel pump pressure and consider replacing the filters if you have not already done so. You can also pull the #4 plug on the MPEM and start checking electrical components with your multi-meter. Have you ever sent the fuel injectors in for cleaning? Good Luck !!
 

changetires

Active Member
Messages
42
Location
Mobile Alabama
Water Crafts
1999 GSX RFI
1999 GTX Limited
I bought this Seadoo from PO and it appears they changed that water valve because the cap has 2 ears that look like mounting holes. Plus it was connected to he muffler with a 2 inch long piece of clear rubber tubing.
 

etemplet

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Messages
3,203
Location
Louisiana
Water Crafts
1996 SPI, 1996 GTX, 1997 GTX
I'd like to know what is UP with those ears. I hacksawed them off my person ski. LOL Freakin stupid idea whoever came up with that. LOL Unless I'm missing something. I told the guy yesterday, I"d pay good money for training on how to get those off and on. :D :D :D I have method but I still love hatin on them. LOL
 

mikidymac

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For some reason Seadoo changed the caps. It’s the only ones available.
 

changetires

Active Member
Messages
42
Location
Mobile Alabama
Water Crafts
1999 GSX RFI
1999 GTX Limited
The Dremel is gonna take care of mine and the piece of rubber tubing is not going back on either. I don’t know why anyone would do that unless it was to make it easier to clean out sand. I am gonna have to do new rings after this season anyway since my compression is down to 110 on each cylinder.
 

etemplet

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Messages
3,203
Location
Louisiana
Water Crafts
1996 SPI, 1996 GTX, 1997 GTX
I am a hacksaw man !! :D Then I use a coarse file. I'll tell you this whatever little bump you leave the spring will hang up on when you' re putting the top back on. Might be just me but I've though. LOL I just cut the one ear off that bugs me and leave the other one alone.

Dang 110psi and it performs OK on the water?? I always say mechanical equipment can't read. :) At that level of wear I'd be concerned of a ring hooking one of the ports if one hasn't already. I've seen a lot of cylinder damage and certainly piston damage at 130PSI readings. Save the ta-tas !!! Pull the head and have a look. Good Luck brother !
 

etemplet

Well-Known Member
Messages
3,203
Location
Louisiana
Water Crafts
1996 SPI, 1996 GTX, 1997 GTX
I just bought a 1999 GTX RFI and decided to pull the engine to do the top end. I've done several with th engine in the ski. I don't know which is the more lazy method, leaving the engine in or pulling it out.
 

changetires

Active Member
Messages
42
Location
Mobile Alabama
Water Crafts
1999 GSX RFI
1999 GTX Limited
I may have a bad gauge I mean it is from Harbor Freight. I have a friend with a snap on gauge I will use to verify with. At least they were reading the same with the HF.
 

mikidymac

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1996 XP
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1991 Superjet
2001 Superjet
Do not trust or buy the HF compression gauge. If you look at almost all the low numbers reported it's from a faulty HF gauge.
 

changetires

Active Member
Messages
42
Location
Mobile Alabama
Water Crafts
1999 GSX RFI
1999 GTX Limited
Got another gauge today and compression came up to 150 psi on both.....I guess I ought to find a better gauge
 

mikidymac

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That’s great. The HF ones aren’t even good enough for the trash can.
 

changetires

Active Member
Messages
42
Location
Mobile Alabama
Water Crafts
1999 GSX RFI
1999 GTX Limited
New diaphragm came in today. Dremel the mounting ear off and hooked the water valve all back up and ski sounds good just gotta get to the river and run
 

changetires

Active Member
Messages
42
Location
Mobile Alabama
Water Crafts
1999 GSX RFI
1999 GTX Limited
Ran GSX RFI ski today and the new muffler rave diaphragm let the rpm get up to about 5100 before it starts losing power the more throttle I give it. I let off the throttle rpm will of course drop off to around 3500 to 4000 and then I can give it throttle to ~ 5100 and the process starts all over.....where do I start?
 

mikidymac

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Location
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Water Crafts
2003 GTI
2001 XP
1996 XP
1996 HX
1991 Superjet
2001 Superjet
Fuel, either pump or injectors.

I would check compression and make sure you aren’t loosing a piston.
 

changetires

Active Member
Messages
42
Location
Mobile Alabama
Water Crafts
1999 GSX RFI
1999 GTX Limited
Miki.... see if this is a problem....I unbolted the injector rail but left the fuel line connected.. removed plugs and put plug wires on grounding bar. Had someone crank the engine over using the start button then they slowly started giving it throttle about half throttle the injectors quit pulsing a spray.


I installed a new Bosch fuel pump this winter.
 

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