1994 GTX Project

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Nilet6149

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Hi there! I have owned this ski for a few seasons but at new to digging into the repairs on my own. There is a similar thread which is old that almost exactly depicts the issues I am having titled “1995 gtx cuts out stalls full throttle” (sorry, forum won’t let me post link)
But that thread is dead. I followed all of the same steps that the gentleman in that thread did, but to no conclusion. I will post pictures later today, but wanted to lead turn it. In summary: the ski will start and idle fine, but as soon as throttle is applied, just produces a low rumble with no rpm increase. If I feather the throttle I can get an initial RPM spike, but then the ski immediately goes back to the fore mentioned behavior. So far I have:

1. Cleaned/inspected all fuel lines
2. Cleaned/inspected all fuel check-valves
3. Pulled the dual-carb assembly. Cleaned all ports, checked gaskets, inspected diaphragm, cleaned screens.
4. Cleaned flame arrestor.
5. Replaced spark plugs and checked good spark
6. Cleaned fuel sediment bowl
Any more suggestions or directions to similar threads would be greatly appreciated! Thanks!
 
If you didn’t rebuild the carbs using new Genuine Mikuni parts then that’s where we will direct you first.
 
If you didn’t rebuild the carbs using new Genuine Mikuni parts then that’s where we will direct you first.
I haven’t actually rebuilt the carbs at this point. I just cleaned them out. There weren’t any real red flags with the carbs that would warrant a rebuild from my perspective. It looks like the guy before me had probably rebuilt it and the entire assembly is genuine parts. I am also creating a video as I go which I’ll be posting to YouTube so I can get a visual look as well. I’ll probably order some carb parts to have on hand though so thanks for the tip!
 
Thanks. Just ordered a carb kit. I’ll post the results. Are there any other smoking guns to look for in addition as I pull it apart the fuel system in addition to what I have covered thus far? Definitely not trying to be a one off “help me” situation. I want to give good step-by-step “how I fixed this” tips for others in my situation, and be thorough.
 
Update:

Finally received the Genuine Mikuni Carb kit after it being on backorder (Darn Virus), and followed the carb rebuild guide on this site. Used SeaDooSource to find the original specs and followed those in setting the screws, and pop-off.

Results:

Still having issues at higher speeds and throttles. The ski goes right up to the limiter off the line, planes out, and then has massive throttle cutbacks at two noticeable times. First, if ANY amount of turn is initiated, the throttle starts to cut back commensurate with the amount of turn. Second, about 3-4 seconds after planing out it starts to cut back to about ~10MPH. Additionally, it won't reach max rpm again unless you let it idle for ~30 sec or so. Then back to the start., Otherwise, it fires right up, idles properly, and runs smoothly.

EDIT: After reading as much of the shop manual as I could last night, I’m thinking the high speed screws could be the culprits, but I’m not sure and even the shop manual talks about avoiding tuning the high speed screws. Right now they are set to defaults, any tips on this? Thanks.
 
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No, you are starving for fuel and will seize the engine if you keep running it that way.
1. Did you replace the needle and seat?
2. What carb spring did you use?
3. Did you replace the fuel lines?
4. Did you replace the fuel selector?
5. Did you replace the fuel strainer and/or strainer o-ring?
 
Go through all of the above, and pay extra attention to the fuel/water separator. It’s a common place to get air leaks, and if the threads on the cup are worn or it’s not screwed on tight, it can do some weird things when turning as the fuel sloshes from one side of the bowl to the other... It’s not common at all, but I’ve had one get loose after jumping a wake and it took quite a while to figure out since it was such a fluke thing...
 
No, you are starving for fuel and will seize the engine if you keep running it that way.
1. Did you replace the needle and seat?
2. What carb spring did you use?
3. Did you replace the fuel lines?
4. Did you replace the fuel selector?
5. Did you replace the fuel strainer and/or strainer o-ring?
Thanks for bringing that up, I did replace the needle and seat.
2. I used the original spring. It’s the darker colored one and slightly different tension than the ones provided with the rebuild kit so I didn’t want to change them.

3. All new fuel lines after I bought the ski.

4. Originally had bypassed the fuel selector, but put a new one in when I did the Genuine Mikuni carb rebuild.

5. this is actually an Interesting point. The fuel strainer cup screws on, but has a “sweet spot” where I can tighten it, and if you screw a hair more it pops off of the threads. I did not check the o-ring on that either.
 
Definitely replace the water separator then. That’s how mine was when it started acting up.
UPDATE: JeremyD615 & mikidymac... You guys rock!

I took your advice and paid attention to the water separator. Fired it up and noticed sloshing in the bowl. I pulled the bowl off and noticed the O-ring was swollen majorly, and the top round of threads to the cup were pretty well shaven off.

After plugging in a new fuel strainer, the ski runs like an absolute champ. New bowl fills completely, and no lag from the throttle in any regime! Thanks a ton to everyone on this forum - even other threads. You guys are life savers! Still have some additional updates to the ski I am going to make, and will continue to update the thread with any new lessons learned along the way. Thanks again.
 
New Issue:

Thanks again for all the help over the past few weeks! Took the ski out last weekend and had a blast. Noticed now a red battery light will stay on when running the ski. Not sure if it is continuously discharging, but had a full day of good use with no problems starting or running. Could this be due to a faulty rectifier? I’ve read some other posts on the forum about this being an issue, but can find no mention of it in the shop manual, or maybe I am just missing it?

Edit:The battery light stays on even with a fully charged battery.
 
First check the battery voltage while running. You should see 13.5-14V. If it ran all day, it’s probably a fault in the gauge itself, but let’s verify you’re charging before we make that assumption.
 
So right after we got it running, A dude wrapped a ski rope around the drive shaft, and now the jet ski is grinding and popping. Checked the visible areas of propulsion from the drive shaft down to the impeller and it’s all free of debris, unbent, and tight. Assuming/hoping all that got stripped was the rotary gear. Any chance anyone has any other insight, or can point me in the direction of a thread to remove and split the case? Thanks!
 
Pull the pump and driveshaft and inspect the splines on both ends before you start planning on pulling the motor. It may be something far simpler than a stripped rv gear.
 
Pull the pump and driveshaft and inspect the splines on both ends before you start planning on pulling the motor. It may be something far simpler than a stripped rv gear.
So I finally got around to pulling the pump off tonight. When I was in the process of pulling it, I had been just poking around, and found that I could wiggle the impeller around pretty noticeably with everything installed, which I found odd.

The guy before me had caulked the pump onto the jet ski, so it took some elbow grease to separate it from the hull. When it came out, the entire drive shaft had rusted into the pump and the drive shaft ripped out from the front with it. I was finally able to dislodge the drive shaft from the impeller shaft, and I will post a picture of it tomorrow to see what you guys think (whether or not it looks ok? I’m not 100% sure if it is in ok shape or not). What was super troublesome was that when I removed the cap off of the pump to try to troubleshoot the play in the impeller, it was a giant mess of rust and goo, and by grabbing onto the impeller shaft, I can easily shake it around. It seems like whatever bearing is in there is completely shot. I watched a video about doing a pump rebuild, and the guy uses a giant press and a ton of tools i don’t have around. Does anyone have any knowledge on this? Should I just buy a new pump? I know I can get a press for about $250, but am curious if the rebuild is worth it? The only pumps I can find online are about $450 and don’t have the two tubes on top of the pump? Not sure what those tubes are for either. Thanks in advance!
 
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You dont need an giant press or much in the way of special tools. Just makes for an easier install and a more impressive thread or website to read online.

The two tubes are just screwed in. Yours will come right out. Just be careful, since most are plastic.

That ski does not have a removable shoe so those earlier pumps are siliconed in. Takes almost a whole tube of ULTRA BLACK to seal one back on.

Your pump is most likely all aluminum or could have a brass core. Tear apart and check all machined surfaces.

The shaft has a flange that a flat needle bearing rides on. If yours has taken too much heat, it will actually mushroom really bad. The needle bearing will be totally disintegrated. The thrust washer will be anything less than pretty.

If there is still signs of oil in there you may be lucky and the pump housing is not damaged where the flat thrust bearing washer rides. So can possibly rebuild it.

The shaft can be discolored and still salvageable. Preferably no pitting or diameter of shaft. Definitely none on the thrust face tho. After polishing will determine the condition. Discoloration is common.

No noticeable groove where seal rides on the shaft. If it polishes out then you are good.

The needle bearings can be knocked out of the housing with a large flat washer.

The best way is each one comes out that end, not both on the same end.

You need a thick steel washer just under diameter of needle bearing. Flats need to be cut on both sides so it can be turned and inserted in between the first bearing being removed. Then socket and extension can be used on the other one.

New bearings will be installed from each end. Be careful careful not to collapse the rolled edges if trying with a hammer and socket. Not the best way.

I prefer a press. Alternate is using a piece of all thread and pulling one in from each end.

A manual arbor press works the best. Hydraulic not so much.
DSC04850.JPG
This is the little giant I use. It is amazing how much feel you get when using an arbor press. Not the same with a hydraulic one. If you find a shop with one large enough for the pump to fit under then will work fine.
 
The 94 GTX ski is the first really high performance three seater. It has enough horsepower to run well, even with a passenger. The hull stays planted in the water. This is something that wasnt so good with the smaller engines in same hull.

The deep foot wells are perfect for someone that wants to go fishing somewhere secluded or even scuba diving. It is an all around solid ski well worth riding. It is more than capable to pull a slalom, tubes, kneeboards or a wakeboard.

I have wondered what this hull would handle like with a 951 in it. It had crossed my mined doing an engine swap for offshore racing.
 
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