96 XP low speed bog

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Dman142

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This problem has just recently crept up in the last week or two. It almost seems as if the exhaust is being blocked as at first start of the day, the engine will not accelerate out of the hole. No matter throttle position, I just get a ‘bwaah, bwaaaaah” with a stutter can be felt, almost like it’s running on one, but it’s not. I can hit the kill button, then upon pressing the start button and giving it 75%-100% power, it will try to plane out and repeat this until it planes out and it’s good to go. It can take up to 6-7 times in order to plane out and continue. At times, I’ll get about 20’ and seems ready like everything is good, then I get the same bwaaaaah. This is almost simultaneous procedure. Instant it starts, hammer the gas. Sometimes it will clean up and run great until it sits too long, then starts the pattern again.
It starts and idles great. I don’t suspect it’s anything like compression, or carb issue. It’s similar to a a snowmobile having the exhaust plugged with snow.

Runs great for the day with no issues, except for a long break in riding. Spot on otherwise. No issues to note. Heck of a ride, but gets old, always having to wrench.

I am curious how anyone keeps these jetskis running as each and every time, a new problem creeps up. I can count on one hand in two years how many rides I’ve had that included a 100% problem free day. Might be heading to the burn barrel shortly. I’d have to guess literally 100 plus trips to the lake trying to get it to run right. Sorry for the rant, but I am so frustrated.
 
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Check your battery first,,,do a load test on it,,,check your plugs,,,check your spark,,check that it is charging.
 
The battery was pulled out a GP800 and is very strong indeed. Have not had a issue with that yet. Can crank the motor over easily and for many attempts if need be.

I can check for spark while in the driveway. Plugs have been replaced recently, but who knows, it may have one fouled plug, when down low in the RPMs. Stator and VR have been replaced while chasing other problems. After riding 2-3 hours, the battery is good, it stays charged otherwise I imagine it would be dead by then if not charging. I can check that too.

You think it’s more electrical than something else?
 
That sound sounds so familiar to an 800xp i once was diagnosing,,,turned out be the coil,,,it would start on land no problem,,,but fall on its face 40 feet out in the water.
 
Had the exact same symptoms on my 96’ XP, it was the voltage regulator.

Try disconnecting the red wire from the regulator. Worth a try even though you already replaced it. Easy and free to check.
 
If you do decide to give up on it, give me a call. I sent you a PM with my number the last time you had trouble getting it running.

I agree with Miki. Pull the red wire and see if the problem persists. Careful as the battery won't charge while it's disconnected. Remember, champ out of water, chump in water. Nearly any seadoo that's kinda running can rev out of water. To really find the problem you have to have the impeller submerged. I had the same problem on my 96 GTX... Then it got worse and wouldn't go above 20 mph ever. Replacing the rectifier solved it.

In terms of "how does anyone keep these running", I've gone through my 96 GTX and fully restored the mechanicals. I'm down to the last couple of things (new gas piston for the hood and replace the aftermarket starter). So far, 40-50 trouble free hours. But I've always bought OEM or top quality parts from osdparts, and I've even swapped a couple common failure parts that were working (fuel selector and o-rings). I've probably spent $400 on new parts to replace old ones that were operational, because when it's time to play, I want to play, not wrench. I treat it a bit like a plane: replacing parts on a maintenance schedule instead of when they fail.

Compared to the cost of a new or newer seadoo, I'm still WAY ahead, even spending a little extra money and going through everything to look for problems. Also helps that I live on a lake... Testing doesn't take too long.
 
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Thanks for all the suggestions! I really do appreciate the help and advice. I am hoping to test out these suggestions today.

I did get your message with your number Lothsahn. I will keep it in mind. The ski is in really good shape all around. I waffle back and forth on dumping it as but is so fun to ride compared to the big rig 4 strokes.



My question is: Why would it be the coil or VR? What role to they play as the possible cause? I’m always up for learning the “why” part.

I am “fairly” competent at 2 stroke operation as I hobby in outboards and boats. They seem more simple to me. Again, my thanks to all who replied.

Update: it went great with the Red VR wire disconnected!! I am super pumped!!!!!
Connected the reds again and the same symptom showed up. Runs awesome. Now into find the other VR.
About how long could it sustain not having the battery charging? Having family up tomorrow and wondering just in case I can’t find the old VR.
 
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Turns out I don’t have an extra VR here. I have one from an outboard that matches wires—3 yellows and one red. Dare I use it?
 
You should be able to run most of the day with a fully charged battery and not starting all the time with long cranking. It's basically known as a "Total Loss" system and is what most of the race skis were back in the day. No harm will come to the ski but just remember once the battery is dead so is the ski.

The issue with the VR is when they go bad they send AC voltage into a DC system so it freaks out all the electronics and not every ski reacts the same so the symptoms can be different. I have found the Aftermarket VR's to be hit or miss but for the price I just buy a couple and try them until I get a good one.
 
Do these have a rectifier also? Are they one in the same?

I spliced in the one I have here that matches the wiring perfectly.
be going to test it shortly.

However, if we could ride a couple hours with the VR not plugged in (red wire), that should suffice for the weekend.
 
Regulator and rectifier are the same on these, we just use different names for the same part.

Given the potential to fry the MPEM's on these I wouldn't just start splicing in random parts.
 
I have the proper one ordered and will probably just unhook the red for tomorrow.

I can’t believe it really was the VR. I’m still in shock. This is the first time in history was given advice and it actually worked!

Most of the time, my problems are the one in a million scenarios. I really think I’ve found the best PWC forum! You guys know the stuff in-depth and dang, it’s impressive. Many times advice is very generic and common sense stuff, which for some people, is the answer. But for the nitty gritty, this is the place to be.
Once I get to ride it more than 2 days in a row, I’ll post an update.!
 
Well, that lasted about 1-2 minutes. With the VR red unplugged, it still bogs and gurgles around.

I tested yesterday with my make shift VR and went fine. Then I put the OEM back in and left the red unplugged, just for peace of mind and advice from here.
So what exactly do the yellow wires do? They come from the stator I believe and that power goes to the VR to be controlled to a steady level? That system ever fail like this? If the stator is good and producing energy, the VR would do its thing with it without charging the battery? Or by unhooking the red, that eliminate the charging aspect only? Perhaps the red does something else too?
Sorry for the questions and lack of knowledge on the details.

Begin rant: At this point, It has taken so much time and energy away from my life, if running, it’s gonna be WOT until it blows up, sinks, catches fire, or falls off my trailer. I’m not even sure I’d wish this ‘ski on my worst enemy.
End rant.

Calmed down: I really hope it works well the next time out. It sure is fun to drive and the information I’ve learned is very valuable. I anxiously await more knowledge to come so I can fix the space shuttle if I’d need to.
 
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The stator produces AC power when the engine is rotating. That power is produced in separate coils, each of which is attached to one of the yellow wires.

Unfortunately for the stator, sea doos don't run on AC. The electronics are all DC based, which means the AC has to be converted to DC. This is what the Voltage Regulator (VR) does. It's also called a rectifier.

It's job is to turn the AC current into DC current st the right voltage. The systems on the sea Doo are designed for approximately 11-14.5V DC operation. When the sea Doo is off, the lowest voltage a healthy battery produces is around 11V DC. When it's on, the voltage regulator should not output above 14.5V, even at WOT.

Each yellow wire connects to a stator coil but the red wire supplies the DC power to the rest of the electrical system, which powers the seadoo and charges the battery. When you disconnect the red wire, you isolate almost all problems caused by the stator or voltage regulator.

If the voltage regulator fails and starts providing AC current into the DC system, or provides DC power above 15V, the computer will either malfunction or enter a safety mode where it cuts the ignition, and the sea Doo will bog. Disconnecting the red wire allows you to diagnose if this is going on.

If the red wire is disconnected, it doesn't matter if you're using a good, bad, OEM, or aftermarket VR. It's essentially a paperweight at that point. Since you're having problems when the red wire is disconnected, you have problems outside the VR circuit.
 
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As for your specific issue, you've tried a lot of things. When it runs rough, does pulling the choke help at all?

Did you ever replace the fuel selector?

Do you have access to a replacement mpem you could try?

Have you checked compression when the engine is cold? Maybe as it warms up something changes?

Attempts to fix:
New fuel lines and filters
Stator-replaced
Voltage Regulator-replaced
Carbs from another machine. No change.
Factory carb settings and adjusted. No change.
Plugs/caps
Dielectric grease on all connectors.
Inspection of each electrical box. No visible issues. No blown fuses.
Cleaned RAVE
Compression at about 145-150
 
Strike all the info indicating it was fixed. Rode about 7-10 minutes and the problem came back. This was with my VR installed.

WOT does nothing except make the ski shudder and shake. On occasion, it seems to want to go, but can’t. Once in awhile, I can hear the Rpms surge just slightly

Compression: 145 warm.
Fuel selector taken off.
Choke does nothing except bog it more.
No spare MPEM.

I’m going to focus in other areas of concern. Perhaps the coils get warm and go haywire?

Lothsahn—-almost ready to call you…..

I have rebuilt countless outboards and sleds in my life and have been stumped on 3 rigs over the years. This might be 4.
 
POPPS said he had a coil do that once, so yes, it definitely could be the coil. My 96 GTX had this exact behavior, but it was the VR, which isn't your (only?) problem.

For now, I would definitely disconnect (and leave disconnected) the red wire from the VR while you troubleshoot. It's possible you have multiple issues, and leaving the red wire disconnected while you troubleshoot rules out a bad regulator. You really don't want to chase a problem from two causes. Once you get it reliably working, then you can hook a known good VR back up. Go methodically--one change a time.

You'll have to charge the battery between rides with an external charger. When you do that, be sure to remove a wire on one of the battery terminals so the battery charger doesn't hurt the mpem. The mpems can be sensitive to overvoltage or boost starters.
 
I happen to have a coil set from my Doo sled and it’s the same as the ‘ski. I put that in last night and will try today. I will test without the red wire hooked up to eliminate that part of the system. Will report back later today.
 
Well, so far so good with the new coils ! They match perfectly. Ran about 1/2 hour-45 minutes and went perfectly. The red wire is not hooked up. Tomorrow, I’ll hook it back together and hope for the best.
More updates to follow.
 
I’m going to count today as a success. Went out for about 2 hours, trading riders and such. Took a couple breaks of about 1/2 hour and each time, it did the usual garbled mess upon starting up. However, both times I was able to clear it out by starting ‘er up, and immediately pin it. Then it went fine for the rest of the session. So whatever it is, it creeps up when it’s sitting.

Should also add this was with the red wire hooked up on the VR.
I don’t know why but I keep thinking something with the exhaust system. Seems like someone is holding their hand over the exhaust. Would it make sense that when pinned to WOT immediately would create enough exit pressure to clear out the obstruction of sorts? I have no knowledge about how the exhaust on these works because of the water factor. I could be way off base too since I can’t figure it out. Just thinking out loud.
 
I thought of that today also. Don’t know why I ruled it out but I do have another set of carbs that I can throw on. Maybe it’s flooding itself out over time.

However, it went fine at the launch right away after sitting overnight, but on many occasions, it’s after a pause in riding.

There’s just so many could be this, could be that, try this, do this, what about this, etc. I swear I am reasonably competent.
 
It doesn't have a diagnostic computer, so it can't tell you what's wrong. There's always a bit of trial and error. On the plus side, it's simpler so there are less possibilities. Having to try things isn't about your competence... it's just reality.

My seadoo sometimes doesn't like to start when it's warm. Cold is fine, hot is fine, warm sometimes takes a little encouragement, but fires up after 2-3 tries (cranking for a second or two each time). It also loads up if I idle for 45 seconds or more, and will quit if I suddenly give it gas, which is apparently common for the non-accelerator pump models.

If you have two sets of carbs but have never rebuilt either set with genuine mikuni, it'd be good to do that. When I've pulled apart carbs on both of my seadoos each needle valve had a groove from where it sat and it didn't make a good seal. These things wear with age and often in the same way, so a second set that's also not rebuilt is not necessarily good.
 
Mechanical trouble shooting is a process of elimination. Imo first place to start is the fuel system. That includes more than just the carbs. You need to go through every inch of it. Fuel lines, both check valves need to be functional on the vent, fuel selector, water separator (especially the oring), rebuild both carbs with genuine mikuni parts new needle and seats. Leak down test the carbs verify popoff. These machines are really simple once you go through a few
 
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