97 GTX can't get over 4k rpm w/o viloent sputtering and cutting out

[rawdog2386]

What are we working with:
1. New SBT 787 installed and pump rebuilted by a pro early this year.
2. Ran for 8 hours on it no problems.
3. Problems started acouple months ago. Took the ski out and couldn't get on plan/over 3k with out the rpms dropping super low in sputtering fits and then would cut out... Would ALWAYS kick back on and do the same thing.
4. So what did i do?
- Rebuilt the carbs to spec and factory settings. -Checked fuel system for blockages -New spark plugs -New gas. -Battery checked to be 12.7v with out it running -Didn't check voltage at battery when running.
5. Took it out and had same problem couldn't get over 3.5K-4k this time. Anytime i try to throttle higher then 4k rpm the motor would sputter violently and drop.
6. Read about the rectifier going bad. Replaced it with the cheapest one i found on ebay.
7. Ran like a dream!!!!! 6500 rpms at 51 mph.
8. Acouple weeks later, while keeping the ski connected to the battery with no trickle charger. I took it out, sputtered at 3k again but as the battery got charged up by the stator while riding around on it below 3k all of a sudden it's like the ski was 100% again. I went through an entire tank of gas no problems! This time when i put the ski up i disconnected the battery and kept it on a trickle charger.
9. Took the battery off the trickle and put on the ski, ran it it for about an hour and the same thing started happening again. Couldn't get over 3k. Sputter and sometimes completely die but would always start right back up. Then this time it was as if the battery just died and couldn't turn the motor over. I was stranded. I thought the stator has gone bad which made the battery die out. Walked the ski home.
10. Charged the battery back up, ran it on the trailor, read 12.7v without the motor on. Took the ski out and from the beginning the ski couldn't go over 3k.

Questions: What should the volts read at the battery when the starter is starting and when the motor is running?
How can i determine if the stator is not providing enough juice to the battery? Are there other components between the stator and the battery that could hinder the battery from getting charged? Is it possible that the aftermarket rectifier, that seemed to originally fix the problem, go bad and i just need another new recitifier?
What to do?

 

[jts32]

Disconnect the red wire from rectifier. Test with a multimeter. Positive lead on red wire and negative lead to a ground. With ski running about 5500 rpm, DC voltage should be between 13.5-14.8. It ran good after installing the cheap aftermarket rectifier, so my guess is it also went bad.

 

[etemplet]

I will be following this thread. I just swapped out a rectifier on my 96 GTX with one from another 96 GTX. Mine is having the same problems but after the ski gets past the initial running bad (around 3k - 3500) it comes on pretty strong. Kinda strange cuz it does it more when it is cold. Good Luck man !!

 

[rawdog2386]

Disconnect the red wire from rectifier. Test with a multimeter. Positive lead on red wire and negative lead to a ground. With ski running about 5500 rpm, DC voltage should be between 13.5-14.8. It ran good after installing the cheap aftermarket rectifier, so my guess is it also went bad.

Since I will have to do this on a trailer hooked up to the hose what should it read at the say 3000 rpm? Thanks for the help!

etemplet- I've been reading your posts recently about your problems with similar skis. The problems you have on the top end definitely rhyme.

 

[mikidymac]

On the trailer with the ski off it should be at least 12.5V and running at about 4,000 rpm 13.5-14V. WHen cranking t should not drop below 12V.

 

[kswiatk]

Had a similar issue with a very weak battery. Would cut out at 4000ish rpm and randomly would work fine after riding for a bit. Replaced the battery and all my problems went away. Im guessing my rectifier maybe on the way out soon, so I am keeping an extra OEM handy.

 

[rawdog2386]

Update: Replaced the rectifier.
-Measured the Voltage at the BATTERY:
-Motor not running =12.5v
-Start motor = 11v
-Motor running 2900 rpms = 13.5v

Replace the battery?

 

[rawdog2386]

On the trailer with the ski off it should be at least 12.5V and running at about 4,000 rpm 13.5-14V. WHen cranking t should not drop below 12V.

Should I replace the battery knowing the previous post's info? 11v at start.

 

[rawdog2386]

I think I'm going to replace the stator/magneto. Are their electrical checks to see if the magneto has gone bad?

 

[skiasylum]

If you have doubts about your battery replace it.

 

[etemplet]

I think I'm going to replace the stator/magneto. Are their electrical checks to see if the magneto has gone bad?

Yes there are checks you can do but I'm not sure they are always 100%. They are in the manual. The recommended a test plug on my 96 GTX but I was able to get in there and get readings.

 

[mikidymac]

If your at 13V running at 2,900 rpm your stator, magneto and regulator are working fine. Don’t replace it if it ain’t broken.

The 11v could be the battery, starter or cables. Keep it simple, if the battery is old replace it first and/or have it load tested.

 

[etemplet]

Hell if I'd go for the stator without good reason. There are some good tests with the engine running to identify which part is bad... if any.

 

[rawdog2386]

Ordered a new battery and ordered two new aftermarket Rectifiers. Hopefully one of those will work. I could not find an OEM rectifier with Part number 278 000 443. I only saw rectifiers that were advertised to "fit OEM"

 

[GGuillot]

What should the volts read at the battery when the starter is starting and when the motor is running?

Starting, 11-12 volts, running 13.5 volts..

 

[rawdog2386]

Replaced the rectifier and the battery.
Ran the ski on super flat water first time this season.
Ran at 5k rpms for 10 mins. Then 5500. Then 6k rpms. All smooth running rpms.
As soon as I punched it to max rpms (6700rpms) it shut off completely.
Started right back up.
This time I could only run a max of 5500rpms without it sputtering. If I gunned it above 5500 rpms it would shut off completely.
THIS IS THE PART THAT MADE ME THINK I HAVE A SHORT.....
Any time I hit chop or would "dolphin" it would sputter or shut off while running anything above 4500rpms. I got two wires too close to each other and when it shakes the wires short.

Why do I have a short? It's a fact that when voltage increases-> resistance decreases.
The higher my rpms = higher voltage = lesser resistance = higher probability of shorting between wires.
Is my electrical logic sound?

If so, where do I start chasing the short? What are the major wires that I can change out to shot gun the answer? The water tight electrical box that houses the rectifier has wires looking like a rats nest. They are everywhere. Let me know your opinion.

Battery Info:
Resting volts of battery not hooked up =12.8v
Hooked up to the ski = 12.67v
starting volts = 12.4v
Running volts 2900 rpms = 13.54v
4000rpm running volts = 14.5v
After running the ski for 30 minutes battery hooked up to ski not running = 12.83v
Rectifier, battery, stator all running good.

 

[GGuillot]

It sounds like a fuel delivery problem, not electrical. I'd have a look into the carbs and do a bypass on the fuel selector. Do the bypass first, see if anything changes.

 

[rawdog2386]

I ran vacuum checks on the carbs all the way back to the selector and the tank last year when this problem started. How would you bypass the fuel selector? Run a fuel hose directly from the carb's to the tank? All the fuel lines are brand new and carbs rebuilt last year with muniki parts.

 

[GGuillot]

I ran vacuum checks on the carbs all the way back to the selector and the tank last year when this problem started. How would you bypass the fuel selector? Run a fuel hose directly from the carb's to the tank? All the fuel lines are brand new and carbs rebuilt last year with muniki parts.

Just remove the res line off the fuel selector and run it to the input on the fuel strainer under the steering. The line you removed from strainer loop it back to spot where you removed it from selector and turn the knob off. Or take the res line off the selector and go directly to the carbs. You can do that direct connection to test if the strainer is good or not.

Narrow it down basically, I had a brand new fuel selector causing an issue as you describe. I couldn't reach WOT without it wanting to shut down. I opened the fuel selector and found the rubber insert inside had twisted causing a restriction.

 

[rawdog2386]

Update.
All three hoses have been replaced from the gas tank, to the selector, to the carbs, & by passed the strainer and used a custom inline filter. Took it out and the exact same thing happened.
If you bring up the rpms really slow I can go 6500 rpms at 50 mphs no problem. As soon as i hit the gas hard, whether I'm at 1500rpms or 5000rpms starting out, it sputters and sometimes dies. After it sputters I will go back to half throtal and it will steady out and no sputter.
Conclusion: hit the gas hard at any rpm and it will sputter and might completely shut off. Even after replacing gas lines and fuel selector by a shop.
Cost me 165 in parts and labor.

 

[GGuillot]

Remove the custom inline fuel filter then go try it. Totally unnecessary and you're gonna lean it out. You already have 3 fuel filters in the system and don't need a 4th.

 

[GGuillot]

Update.
All three hoses have been replaced from the gas tank, to the selector, to the carbs, & by passed the strainer and used a custom inline filter. Took it out and the exact same thing happened.
If you bring up the rpms really slow I can go 6500 rpms at 50 mphs no problem. As soon as i hit the gas hard, whether I'm at 1500rpms or 5000rpms starting out, it sputters and sometimes dies. After it sputters I will go back to half throtal and it will steady out and no sputter.
Conclusion: hit the gas hard at any rpm and it will sputter and might completely shut off. Even after replacing gas lines and fuel selector by a shop.
Cost me 165 in parts and labor.

I went back and reread this thread. Here's some questions....when you say carbs "rebuilt with mikuni parts and to factory spec". Are we talking genuine oem carb kits? The kits alone for a dual carb w/needle seats is about $125 -$136. Did you pressure ck and ck pop off? Carb torn down to just body with all passages cleared and blown out with compressed air? 4 holes in low speed circuit clear? Jets removed and clear? All ck valves replaced and properly installed with film concave face down? Carbs sync'd perfect? Original spring used? Or verfied 80 gram spring installed?

Each carb LS needles 1 turn out and HS needle 1/2 should yield a solid 6700 on top end and safe setting to deter a lean condition.

Carbs and the fuel system is finicky on these skis, it must be right or issues can occur. I've done 2 skis with 787's and if you're through on carbs and related, it'll reward you with great performance and reliability.

 

[Sportster-2001-951C-Stock]

Revs out with no signs of hesitation then dies like the DESS key was removed? Tough to say if fuel or electrical but pull the red rectifier wire and see if it repeats. If yes, it's a charging system issue.

 

[rawdog2386]

Hey thanks man. Here's the low down. Did exactly what you said. Bypassed the seadoo OEM fuel filter. Kept the online paper filter. Ran it on the hose and watched the fuel lines. Absolutely zero bubbles! Adjusted the high and low screws on carbs. Replaced properly gapped spark plugs. Then...
Took it out on the water. Brought the rpms up slow and it did 52 mph at 6700 rpms again. Good enough for me! BUT then when I would start to punch it from a dead stop would sputter. Never could get back up to 6700 rpms and hold.
Plan is now to go through carbs. Set/ balance pop off pressure between the two and all the other checks the shop manual tells me to do.
AND replace the inline paper filter with a screen inline filter that looks more like the OEM filter. I'm guessing the paper is a lot more restrictive then necessary. What do you think?

 

[mikidymac]

Get rid of the inline filter, there have been many people here that had fuel starvation issues with them.

The factory one works great and is only $22 for the entire assembly. It is also a water separator which is important on a watercraft.