1996 Seadoo Gtx bog over 3/4 throttle

[Skhrris44]

I have a 1996 Seadoo GTX and am having an issue with bogging down at WOT and when making sharp turns or changing directions quickly. I have replaced fuel lines, rebuilt carbs genuine mikuni kits (2 years ago), rave valves, fuel selector, fuel separator, rectifier, new plugs and clipped spark plug wires back, carbon seal, new battery.

If I give the ski 3/4 throttle it will run fine at about 6300/6400 RPM's, but if I go WOT it falls on its face and then recovers and begins to Rev up then fall on its face again and continues this cycle. Idles great but also bogs down if I go WOT out of the hole. If I pull out the choke while holding at 3/4 throttle it tries to die so I don't think its running lean.

This started on the last ride of the summer last year and would only bog down if I was running along and cut the ski to one direction or the other, now still does that but also while going straight. Any info or help would be greatly appreciated!

 

[GGuillot]

Have you played with the HS needles yet? Turn them out and see if you can change it, sounds like its staving for fuel at WOT. I had a bad fuel selector, brand new and the rubber inside had twisted restricting flow. You can also try a fuel selector bypass and see if that changes anything.

 

[JeremyD615]

Take a look at your water control valve, and all of your exhaust hoses as well. I’ve seen some high rpm issues that stem from those things as well...

 

[Skhrris44]

Have you played with the HS needles yet? Turn them out and see if you can change it, sounds like its staving for fuel at WOT. I had a bad fuel selector, brand new and the rubber inside had twisted restricting flow. You can also try a fuel selector bypass and see if that changes anything.

Havent messed with HS needle since i rebuilt carbs, is it possible for it to vibrate out of adjustment? Ill def give that a try tho! Thanks for the reply!

 

[Skhrris44]

Take a look at your water control valve, and all of your exhaust hoses as well. I’ve seen some high rpm issues that stem from those things as well...

I read somehwere that the exhaust hose can collapse, is that what u mean? Also by water control valve is that the race valve looking thing on the exhaust?

 

[JeremyD615]

Yes. The WCV is the thing that looks like a rave valve on the exhaust. You want to make sure the diaphragm inside of it is in decent shape with no holes or water leaking from the housing. The exhaust can collapse, but it’s not very common. Usually after a WCV fails, you’ll see the hose melt between the pipe and water box first.

 

[Skhrris44]

I have noticed a drip where the valve screws into the exhaust, is the piece that valve screws into called the water box?? Could i have an internal issue causing it to leak? Whats the best way to fix or service that WCV like a rebuild kit? I def think my bog is a flood condition.

 

[JeremyD615]

Yes, you can get replacement parts for the WCV valve, and yes, the thing it screws into is called a water box. It acts as the muffler in your exhaust. If you have water leaking there, I would suspect that you have a leaking diaphragm inside that thing, and may have a small exhaust leak at one of the hose couplers. Exhaust fumes in the boat will choke the motor out, and will cause you to go rich, as it displaces the air in the hull.

 

[Skhrris44]

Ok i dug into the WCV and i do have a hole on the bellows so i have one ordered. I inspected alot of the exhaust and dont see any blatant issues. The exhaust hose from the water box to the exhaust outlet is pretty soft, like i can squeeze it closed. Not sure if thats normal or not. I dont feel a hole in the piece that connects the water box to the exhaust. Another symptom that i noticed when it was bogging is when i pulled the filter in the water separator it seemed to be collasped a good bit, not sure thats normal.

 

[JeremyD615]

The soft hose is probably normal. They weren’t a very stiff hose even when new. As long as it’s still springing back to open after you squeeze it, it should be fine. It’s generally the coupler between the pipe and water box that goes, and for some reason it always seems to be on the back side where you can’t see it... I’d pull the coupler and take a good look at it.

 

[Skhrris44]

Ok id like your opinion on something i noticed when im having these bogg issues. I pull water separator bowl and noticed the filter was starting to collapse on itself. Im assuming that means the carbs are sucking more than is being supplied from the tank. So i noticed my gas cap gasket was in horrible shape so i replaced. I also replaced my fuel tank vent hoses as they were the only grey lines i had left on the machine. I noticed that my gas vent that goes out the hull seemed to be clogged, i put compressed air through it until it would vent freely one way. I have also put an entire new OEM fuel separator on the machine. Havent gotten a chance to ride it yet with these changes. Have you heard of the hull vent being clogged cause bog at WOT?

 

[JeremyD615]

It’s possible for the vent line being clogged to cause a bog, but you can check for that by riding with the gas cap cracked open. If the problem goes away with the gas cap venting, you’ve found your culprit.

 

[Fufu89]

I have a 97 seadoo GSX with the exact same characteristics listed.
Have had the issues since purchasing summer 2019.
This winter I decided to rebuild carbs, replace fuel lines & fuel selector. Got it out early this spring, no change in behavior whatsoever. Decided to clean raves, no results. I believe i've got it narrowed down to a couple issues stated above. Exhaust leak or possibly going to check and replace air/fuel check valves. I've spent more time and money chasing this problem than I care to think about to no avail. But this thread along with info gathered from a few others seams to narrow the issue down quite a bit. Going to work on it this evening and hopefully get back soon with good news.

 

[Fether4789]

Have you found a fix yet? I have a 97 spx that acts very similar.

 

[Fudea0691]

Not a clue, I believe I have a leak in fuel line and losing pressure but havent tested yet

 

[rsmkenshannon]

Welcome to the club. I have a '96 GTX. Picked it up for free a few years ago in pristine condition but needed a lot of TLC inside since it had sat for a few years. Spent some cash with a guy who fixed some stuff I couldn't/didn't want to (sator, etc.) ran great a couple of vacations and then it died. Guy wanted stupid amount of money to fix so I decided to do my homework and see if I could fix it. I have replaced all the interior lines, rebuilt carbs, replaced oil tank sensor gasket, oil and fuel filters, check valve functions, rebuilt WCV, replaced regulator/rectifier. rebuilt rave valves, new plugs, clipped spark plug wire ends, replaced voltage regulator. Basically I have pretty much completely replaced all working components inside the ski. Took it to the river two weeks ago and it fires up and idles like new. Hole shot WOT is insane power! but then a second later it throttles down to 3k rpm and won't go over 10-15 mph on wide open throttle. release gas and then WOT again and again insane power and second later shuts down to same again. pull choke while WOT and ski stalls out. I have not tested since I replaced WCV and rectifier but maybe someone has an opinion on this scenario. I'll post what happens next time I take it out with the latest replacements.

 

[rsmkenshannon]

Just an additional note to my comment above...
If you are capable of working on your own ski then all the work I did above cost less than $500. Basically the ski is brand new on all the internals except for the actual engine block which was like new when I picked up the ski. Well worth the money if I can figure out the top end issue.

 

[GGuillot]

Just an additional note to my comment above...
If you are capable of working on your own ski then all the work I did above cost less than $500. Basically the ski is brand new on all the internals except for the actual engine block which was like new when I picked up the ski. Well worth the money if I can figure out the top end issue.

Carbs....or fuel delivery problems is where I'd focus. Specifically, expand on what you did when you "rebuilt carbs"? They need to be perfect, oem kits, ck pop off, etc. Once those are perfect I'd do a fuel selector and maybe also a fuel strainer bypass. The slightest hint of air in the lines causes issues when higher fuel demands are needed.

 

[Donkendave]

I have a 1996 Seadoo GTX and am having an issue with bogging down at WOT and when making sharp turns or changing directions quickly. I have replaced fuel lines, rebuilt carbs genuine mikuni kits (2 years ago), rave valves, fuel selector, fuel separator, rectifier, new plugs and clipped spark plug wires back, carbon seal, new battery.

If I give the ski 3/4 throttle it will run fine at about 6300/6400 RPM's, but if I go WOT it falls on its face and then recovers and begins to Rev up then fall on its face again and continues this cycle. Idles great but also bogs down if I go WOT out of the hole. If I pull out the choke while holding at 3/4 throttle it tries to die so I don't think its running lean.

This started on the last ride of the summer last year and would only bog down if I was running along and cut the ski to one direction or the other, now still does that but also while going straight. Any info or help would be greatly appreciated!

I picked up a clean 96 GTI, all original, low hours (assuming) a few weeks back, ran perfect first 2 trips out, 52 mph. 3rd trip out it started bogging above 30 mph. I checked my fuel filter, it was clean then I went through the daunting task of removing my carbs. to check out their filters and my rear carb's filter had a bit of gunk in it, the front carb was pretty clean; cleaned it up a bit, put it all back together and bogging issue was gone surprisingly. I say surprisingly because the filter wasn't all that bad, but apparently enough when going over 30 mph. Now I just need to figure out my latest issue that has me dead in the water...

Last Saturday I found myself in 6" of water with sand below, unfortunately I panicked and rather then killing the motor, I hit reverse and then proceeded to get back in forward and drove out. Within 1 minute I heard a loud, high pitch winding sound (only one time, lasted about 5 to 10 seconds) and the ski began idling extremely rough and lost power. I tried cruising back with no throttle but within 5 minutes the engine temp light came on, I shut it down and got towed in. Since then I have done a compression test (137 on both cylinders just like before the incident), examined the spark plugs, bumped the starter with plugs out, examined the shaft, impeller & wear ring, blown out the the water intake line (felt clogged for half a second and then blew through, thought that was it but no cigars), ran water through the coolant system in both directions, runs fine in the driveway but horrible when you put it in water. Next, I guess I will check out the impeller shaft reservoir and bearings to see if sand got in there possibly. I would have thought this would've been a common, easy to diagnose scenario, but I'm not finding anyone else that has experienced this problem, ever heard of anything like this?

 

[rsmkenshannon]

Carbs....or fuel delivery problems is where I'd focus. Specifically, expand on what you did when you "rebuilt carbs"? They need to be perfect, oem kits, ck pop off, etc. Once those are perfect I'd do a fuel selector and maybe also a fuel strainer bypass. The slightest hint of air in the lines causes issues when higher fuel demands are needed.

Thanks. It is a brand new fuel selector so sure that's not it. New fuel filter also. It is possible there is some air in the line but wouldn't that bleed out after running it for a while?
After rebuilding carbs we took it to the river and ran it for about 45 minutes even though we could only do about 3k rpms.