Seadoo Gtx help

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Water Crafts
2000 Seadoo Rx, 97 Seadoo Gtx
#1
Hey guys I have a 97 Seadoo Gtx I’m having some problems with. Guy I picked it up from said carbs were rebuilt and he replaced the coil and trigger but it’s having trouble starting. Sometimes it fires up sometimes it just cranks. Also back fired on me once sounded like a gun going off. Today I was fooling with it and grounded the spark plugs hit the button very weak spark couldn’t hardly see it. I had it running like 6 times in a row then it will just crank, Where do I start in tracing the problem down? Is it possible whoever rebuilt the carb didn’t adjust it right? Any help is appreciated
 


Messages
49
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4
Water Crafts
2000 Seadoo Rx, 97 Seadoo Gtx
#2
Hey guys I have a 97 Seadoo Gtx I’m having some problems with. Guy I picked it up from said carbs were rebuilt and he replaced the coil and trigger but it’s having trouble starting. Sometimes it fires up sometimes it just cranks. Also back fired on me once sounded like a gun going off. Today I was fooling with it and grounded the spark plugs hit the button very weak spark couldn’t hardly see it. I had it running like 6 times in a row then it will just crank, Where do I start in tracing the problem down? Is it possible whoever rebuilt the carb didn’t adjust it right? Any help is appreciated
150 compression on both cylinders and clipped spark plug wires back
 
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IDoSeaDoo

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1995 Sea Doo XP800 (future project)
2009 Yamaha FX HO
1997 Seadoo Challenger 4tec
#3
I picked up a ski on the cheap because the ground to the coil was corroded and making poor contact. Check the condition of this wire, and if needed, make a new one. It's a short 2" wire that connects to the coil mount post. You should see a decent spark. Are you using NGK BR8ES plugs? Also, backfiring indicates a lean condition. The carbs could very well be not tuned properly. If you spray some fuel down the throats, does it fire up?
 
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Water Crafts
2000 Seadoo Rx, 97 Seadoo Gtx
#4
I picked up a ski on the cheap because the ground to the coil was corroded and making poor contact. Check the condition of this wire, and if needed, make a new one. It's a short 2" wire that connects to the coil mount post. You should see a decent spark. Are you using NGK BR8ES plugs? Also, backfiring indicates a lean condition. The carbs could very well be not tuned properly. If you spray some fuel down the throats, does it fire up?
I was looking at the coil today and noticed two wires one plugged on each side, is that the wires your speaking of? And yes sir br8es plugs. I got this thing cheap and it’s really nice guy was tired of fooling with it so here we go lol
 
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Water Crafts
2000 Seadoo Rx, 97 Seadoo Gtx
#5
Also what does spraying gas down in the cylinder prove if it makes a difference
 
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Water Crafts
2000 Seadoo Rx, 97 Seadoo Gtx
#6
Also when I have it running I get the idle on the carb and turn it trying to get it to 3000 it will go to about 3400 and then I will loosen it then it will fall low. Then I will turn it back up and it will jump to 4000+ I can’t get it right for some reason it falls or jumps
 
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Water Crafts
1991 seedoo sp
#7
Mine does the same thing!!!!! But it’s been doing fine lately. If you figure it out LET ME KNOW. It runs good but shut it off to go get a glass of water or whatever n then I need to use the starter to crank me back to shore.
 
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Water Crafts
2000 Seadoo Rx, 97 Seadoo Gtx
#8
Mine does the same thing!!!!! But it’s been doing fine lately. If you figure it out LET ME KNOW. It runs good but shut it off to go get a glass of water or whatever n then I need to use the starter to crank me back to shore.
It’s like it runs when it wants to you know? I’d love to know what the deal is
 

IDoSeaDoo

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#9
Also what does spraying gas down in the cylinder prove if it makes a difference
Not gas down cylinder, down carb throats. It would prove that your carbs are not feeding enough fuel. I trust you're choking it when you try to start it? One cause of hard starting can be when your rotary valve clearance is too much. The tolerances expand once the metal gets hot, and it allows one cylinder to pull air from the other vs pulling from the carb. These clearances can become too large on very high hour machines, or ones that ingested water (washed away oil long enough to wear).
But it doesn't sound like you're running till it gets all that hot, right? It starts once, then you shut it off, then it will not start again, right?
Also, I would check all your fuel hoses, especially the places where you have hose clamps. I had a loose hose clamp at the fuel/water separator, and it would suck air. It was intermittent too, as it changed based on how the ski was jostled. Air in your fuel line is compressible, and decreases the potential of the fuel pump. Having clear fuel line or maybe a see-through filter just before the carb can help you spot this issue.
As for tuning the idle, that must be done in conjunction with the Low Speed screw. There is a writeup on tuning these carbs at the top of the 2-stroke forums list (I think they call that a "Sticky").
 
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Water Crafts
2000 Seadoo Rx, 97 Seadoo Gtx
#10
Not gas down cylinder, down carb throats. It would prove that your carbs are not feeding enough fuel. I trust you're choking it when you try to start it? One cause of hard starting can be when your rotary valve clearance is too much. The tolerances expand once the metal gets hot, and it allows one cylinder to pull air from the other vs pulling from the carb. These clearances can become too large on very high hour machines, or ones that ingested water (washed away oil long enough to wear).
But it doesn't sound like you're running till it gets all that hot, right? It starts once, then you shut it off, then it will not start again, right?
Also, I would check all your fuel hoses, especially the places where you have hose clamps. I had a loose hose clamp at the fuel/water separator, and it would suck air. It was intermittent too, as it changed based on how the ski was jostled. Air in your fuel line is compressible, and decreases the potential of the fuel pump. Having clear fuel line or maybe a see-through filter just before the carb can help you spot this issue.
As for tuning the idle, that must be done in conjunction with the Low Speed screw. There is a writeup on tuning these carbs at the top of the 2-stroke forums list (I think they call that a "Sticky").
Thanks for the information. Yes I shut it off when it hits I know better. And it has clear fuel lines, yes I’m choking it bud. Idk it just seems to me like that spark is what’s doing it I feel like I should be able to see it.
 

IDoSeaDoo

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#11
Thanks for the information. Yes I shut it off when it hits I know better. And it has clear fuel lines, yes I’m choking it bud. Idk it just seems to me like that spark is what’s doing it I feel like I should be able to see it.
Well, then pouring a little fuel down the carbs will not make any difference. Worth a try if you have the air muffler off.
You can buy a spark tester at advane auto. It plugs into the boot, and has a ground clamp. It also has an electrode that you can bring further/closer and measure how strong your spark is. I recall mine could be separated damn near an inch and still arc.
And yes, earlier, I was talking about those wires on the bottom of the coil. I would definitely check those real well for corrosion. Maybe even replace the ground wire for good measure. Is the coil cracked anywhere? If you try to start it with the lights off, sometimes you can see a faulty spark plug wire. Mine got old and started to fray around where they come through the electrical box. I found out because they zapped the hell out of me when I was touching them and it was running.
 
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Water Crafts
2000 Seadoo Rx, 97 Seadoo Gtx
#12
Well, then pouring a little fuel down the carbs will not make any difference. Worth a try if you have the air muffler off.
You can buy a spark tester at advane auto. It plugs into the boot, and has a ground clamp. It also has an electrode that you can bring further/closer and measure how strong your spark is. I recall mine could be separated damn near an inch and still arc.
And yes, earlier, I was talking about those wires on the bottom of the coil. I would definitely check those real well for corrosion. Maybe even replace the ground wire for good measure. Is the coil cracked anywhere? If you try to start it with the lights off, sometimes you can see a faulty spark plug wire. Mine got old and started to fray around where they come through the electrical box. I found out because they zapped the hell out of me when I was touching them and it was running.
You the man. And thanks I will go by autozone or somewhere and grab one. The new coil the previous owner put on. One side is a white wire and other is a grey wire I noticed he has the grey cable from coil spliced into the black wire on the starter solenoid plug? Why would it be like that?
 
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IDoSeaDoo

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2009 Yamaha FX HO
1997 Seadoo Challenger 4tec
#13
One of those wires is a ground. On my 787 SPX, the ground wire was about 3" long, one end had a female connector, the other a loop connector. There were several other loop connectors, including one ground from the battery. They were all connected at the bolt at the bottom of the coil. Not sure if this is the stock setup, as that ski clearly was "repaird" by the previous owner.
Are you sure that coil is for a 787? If it's been replaced, I'd check the part number and make sure. You say he replaced it with a "new" coil... where the hell did he find a new part for a 20yo ski?
 
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Water Crafts
2000 Seadoo Rx, 97 Seadoo Gtx
#14
One of those wires is a ground. On my 787 SPX, the ground wire was about 3" long, one end had a female connector, the other a loop connector. There were several other loop connectors, including one ground from the battery. They were all connected at the bolt at the bottom of the coil. Not sure if this is the stock setup, as that ski clearly was "repaird" by the previous owner.
Are you sure that coil is for a 787? If it's been replaced, I'd check the part number and make sure. You say he replaced it with a "new" coil... where the hell did he find a new part for a 20yo ski?
I noticed it doesn’t have any wires under the mounting
Bolts it just has one wire running from each side
 
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Water Crafts
2000 Seadoo Rx, 97 Seadoo Gtx
#15
One of those wires is a ground. On my 787 SPX, the ground wire was about 3" long, one end had a female connector, the other a loop connector. There were several other loop connectors, including one ground from the battery. They were all connected at the bolt at the bottom of the coil. Not sure if this is the stock setup, as that ski clearly was "repaird" by the previous owner.
Are you sure that coil is for a 787? If it's been replaced, I'd check the part number and make sure. You say he replaced it with a "new" coil... where the hell did he find a new part for a 20yo ski?
This may help you see what I got going on somewhat. Out of the solenoid plug someone has spliced the ground to the coil to it and ran another wire to the ground on the battery.
 

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mikidymac

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#19
It looks like some of the wires are not run correctly and yes, there should be a water proof plug on the top of the box. Don't run it like that as it will just fill all your electronics with water.

The wiring diagram is in the service manual that can be downloaded for free online.
 
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2000 Seadoo Rx, 97 Seadoo Gtx
#20
Thank you I ended up fixing the wires I looked up as to what one should look like and followed it, but now I’m just getting cranking. It was running earlier it still isnjust running when it decides to. I have spark I can actually see now
 

IDoSeaDoo

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1997 Seadoo Challenger 4tec
#21
The coil wiring looks to be correct, but that coil looks a bit different from the average seadoo coils I'm used to seeing. I would try to cross reference the part numbers on it. You said you can actually see the spark now, you're saying it's improved over the original configuration? Have you confirmed that both wires are sparking? You can actually plug both plugs and they should both fire at the same time. Also, it looks like your red cable from the battery is frayed at the terminal. Is it okay? Does the ski crank fast when you turn it over? It should crank around 300rpm, with gusto. Your voltage shouldn't drop below 11V as you're cranking. Perhaps your battery is getting tired from all the testing. I usually jumper a big car battery to it if I'm doing a lot of testing so as not to kill the tiny ski battery.
 
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Water Crafts
2000 Seadoo Rx, 97 Seadoo Gtx
#22
The coil wiring looks to be correct, but that coil looks a bit different from the average seadoo coils I'm used to seeing. I would try to cross reference the part numbers on it. You said you can actually see the spark now, you're saying it's improved over the original configuration? Have you confirmed that both wires are sparking? You can actually plug both plugs and they should both fire at the same time. Also, it looks like your red cable from the battery is frayed at the terminal. Is it okay? Does the ski crank fast when you turn it over? It should crank around 300rpm, with gusto. Your voltage shouldn't drop below 11V as you're cranking. Perhaps your battery is getting tired from all the testing. I usually jumper a big car battery to it if I'm doing a lot of testing so as not to kill the tiny ski battery.
Yes sir I can see spark coming from both plugs now. And it cranks fast. When it starts I can cut it on and off like 6 times in a row a run it on a hose but like yesterday I did that and left it and came back later to start it and nothing but a fast crank and still had good spark. And yes both batter terminals are fine.
 

mikidymac

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#23
If you have spark every time and it cranks every time but doesn't run every time then it must be something mechanical or fuel related.
 

mikidymac

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#25
Rotary timing or stripped rotary gear, DESS post losing contact, stator pickup coil. Remember, you need compression (good) spark (good) and fuel to run.

After seeing all the cut wires, missing connections and missing plug, questionable coil I would still suspect it is something electrical.
 

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