96 XP Dropping a Cylinder

[motogotro]

I have a weird intermittent problem with a 1996 XP. Most of the time the ski is freaking awesome, pulls hard and will peg the speedo at 60mph but then it will feel like it drops a cylinder and just runs on one. I believe the problem is electrical because if I can get to someplace where I can mess with it while it is doing it I can get it to start with the rear plug wire on either cylinder but neither cylinder will run with the front wire. I believe the ignition system is the same all the way up to the coil so the last time out I replaced the coil with one that I had from a GSX Limited that is apart right now. The ski initially had the same problem but about 2 minutes into the day it cleared up and I ran 3/4 of a tank of gas through the ski and it ran flawlessly and then, just like that it dropped a cylinder and it didn't come back all the way back to the ramp. I have another coil on order and will try another one to confirm but other than the coil I cannot think of anything in the ignition system that will affect just 1 cylinder.

Now here's another weird thing that makes me think it might be carb related. When it does have the problem, I can turn it off and sit for about 30 seconds and then when I crank it up it will hit on both cylinders for about 10-15 seconds and then drop the cylinder again. That makes me think that one carb is running out of gas and when I sit there it is somehow filling with gas but cannot keep full under load. Also, even when it is having the problem it idles fine and will run okay up to about 1/8 throttle which makes me think its a main jet problem of some sort.. So I pulled the carbs thinking there was something floating around in the carbs that was occasionally blocking a jet but they were clean as a whistle.

Now I'm starting to think the rev limiter is kicking in way early and causing the problem but I don't know of a way to test that other than replacing the computer.

So I'm stumped. The fact that either cylinder will run on the same plug wire and neither will run on the other make me think electrical but replacing the coil didn't help. I've replace plugs and it doesn't make a difference either. If it is electrical, why does it idle fine?

Other than just throwing money at it does anyone have any ideas?

 

[Matt Braley]

This has failed in your front grey electrical box. See if you can get your money back for that coil.

Fits Sea Doo Regulator Rectifier 787 800 XP 95-96 GTX Black 90 Day Warranty | eBay

 

[mikidymac]

Mine did the exact same thing and it was the voltage regulator as Matt B. said.

An easy test is to open the gray electrical box next to the gas tank and disconnect the red wire from the voltage regulator. The ski should run perfect if ti is bad but your battery will not be charging.

 

[motogotro]

Thanks guys. I found a thread that had that same fix so I have ordered a regulator and will give that a try. This makes the most sense of anything so far so I'm hopeful that this will fix it. I never would have found that on my own!

 

[mikidymac]

Why not try pulling the red wire and see if it helps before buying a new one? I would make sure the old one is bad before moving on.

 

[motogotro]

Because mine is inconsistent the test would not prove anything. It ran perfectly for 2 hours with the red wire plugged in so if it runs good with it unplugged it could be because it's unplugged or maybe the problem is just not there at that time. The regulator is cheap enough that I'd rather just change it and remove the possibility.

The regulator is already here and already been installed. The coil should be here today so I'm hoping for a lake test this weekend and if it runs good the entire time then I'll believe the problem is fixed.

 

[Captain24]

That is interesting you are having that problem down in Texas. My 96 behaves almost exactly the same. If I blend out of the throttle when the front cylinder stops producing power the motor will continue to run clean on the other cylinder. This also helps the non-firing plug to avoid fouling to an extent. Eventually the boat comes off of plane and the motor will run clean on idle and up to about ten percent of power. Never enough power or duration to pull the boat back onto plane. It can take significant time before the motor will run normal again, allowing the mind to wonder off, as one idles around the lake contemplating all possible causes. Putting brand new gapped plugs really helps to mitigate the problem for me. But the correct solution has eluded me for years. I buy plugs by the case. When Matt mentions the rectifer has failed, it might be more accurate that the part cannot always tolerate its normal operating temperature. If you have success please let me know.

 

[motogotro]

I took it out this weekend and while it ran great, I got a battery warning light shortly after I left the dock. I pulled the ski and opened the electrical box to make sure everything was plugged in good and while it looked good it smelled like fried electronics so I suspect the VR is fried. I'll do some testing this week and see if I can determine what happened.

 

[motogotro]

Well, the VR was definitely fried. There was a dead short on the battery with the VR plugged in. It looks like the battery failed too as it wouldn’t charge over 9.5v. Not sure what failed first but a new battery and new VR and the ski ran great today. Shout out to Chromebattery for standing behind their warranty on the battery. And thanks to this list for helping me find that problem. I don’t think I would have found it on my own.

 

[Matt Braley]

Your welcome. Happy to help.