1997 GTX wont go past 1/3 throttle

[cloudmaster_321]

Trying to bring this ski back from the dead. Completed a minor restoration and replaced a lot to new.

Took the ski out the other night for the first time, and the throttle won't transition past 1/3rd throttle in the water. About 20mph or 3,500 RPM's. Brought it back to the trailer. Runs normal with no load with the hose on the trailer.

Spark plugs are soaked, and looks and sounds like it's running super rich. These were new plugs installed since the first run on the trailer on the hose this year.

I pulled the carbs back off and went through them to see if I missed something. Checked everything per book. Most I found was the high speed needle on the pto was set at 3/4 turn out instead of 1/2 turn. The pop off's were in the range of 32-35. I had one needle not able to hold 10 psi for 30 seconds. I'll change that out. Arms heights were correct.

I'll reverify the fuel pump check valves. Diaphram test was good. What else would cause a stupid rich condition?

It was suggested to me that the new voltage regulator i got from OSD might be limiting throttle. I was suggested i try unplugging the red, which is the charge output, just to try and see if the rpms go up.

Also snipping the ends of the spark plug leads and screwing the caps back on. I can do that.

I did verify the water pressure regulator setting, and the rav valves were removed, cleaned, and reinstalled.

Anything else I should be looking at? I thought it was a carb issue, but now i'm not so sure.

 

[mbellomy]

I've got the same issue that I haven't had time to figure out yet as well so I'm watching! If you're on the water try bouncing the ski or jumping a wake to unload the pump and see if it jumps past the 3500 barrier. Mine does and then runs at full RPM until I slow down then it's back to the 3500+- RPM barrier. You've hit all the common "fixes" that I've heard of, besides checking the new-style slotted Rave valves? (That's the one and only thing I've tried so far and it didn't work). I personally don't feel like it's a Rave valve issue... either fuel or ignition?

 

[Venturian1]

I've got a similar problem with a 98 GTS, single carb that has an accelerator pump, and discovered that pulling the choke out a little bit while riding it makes it rev up properly. I've been through the whole fuel system a few times. I'm starting to wonder if the restriction in the return fuel line is not holding back enough fuel (needs more restriction).

 

[cloudmaster_321]

I've got a similar problem with a 98 GTS, single carb that has an accelerator pump, and discovered that pulling the choke out a little bit while riding it makes it rev up properly. I've been through the whole fuel system a few times. I'm starting to wonder if the restriction in the return fuel line is not holding back enough fuel (needs more restriction).

i'm not familiar with the "restriction" you speak of in the return line.

 

[etemplet]

Replace the needles and seats and use the 80gr springs. Close the high speed adjusters. Generally when you have good needles the pop-off resets and holds within 5 pounds of pop-off. You should be able to see the needle leaking or determine if the o-ring on the outside of the seat is leaking. I never have trouble getting to carbs to hold pressures close to pop-off.

Sounds like you have a transition issue. Test the nozzles inside the carb throat to make sure they are spraying properly. Should be strong steady streams.

 

[Venturian1]

i'm not familiar with the "restriction" you speak of in the return line.

The book calls it a recharge jet. I think it there to slow the recharge time of the accelerator pump, so it doesn't starve the engine for fuel during this recharge (when you let off the throttle, a spring under the diaphragm pushes it back up, thus filling the accelerator pump chamber with fuel)

 

[cloudmaster_321]

The book calls it a recharge jet. I think it there to slow the recharge time of the accelerator pump, so it doesn't starve the engine for fuel during this recharge (when you let off the throttle, a spring under the diaphragm pushes it back up, thus filling the accelerator pump chamber with fuel)

97 gtx doesn't have an accelerator pump

 

[cloudmaster_321]

Replace the needles and seats and use the 80gr springs. Close the high speed adjusters. Generally when you have good needles the pop-off resets and holds within 5 pounds of pop-off. You should be able to see the needle leaking or determine if the o-ring on the outside of the seat is leaking. I never have trouble getting to carbs to hold pressures close to pop-off.

Sounds like you have a transition issue. Test the nozzles inside the carb throat to make sure they are spraying properly. Should be strong steady streams.

needle and seat in both carbs are new. 80 gram springs are installed. I did test the needle and seat per the book, and they both hold pressure accordingly. I'm not exactly sure what you are referring to with the "nozzles". Are those the three little holes in the body by the butterfly?

 

[etemplet]

Yes, the 3 in line down the middle and the larger one off to the left when looking down the throat. Pop off should be 36-38 psi with the recommended springs. At 30-psi the carbs flood and won't transition. The ski (GTX) gets stuck at 35mph on won't accelerate. If make a small jump or the impeller gets unloaded the engine will transition and the ski will take off for top speed.

 

[cloudmaster_321]

Yes, the 3 in line down the middle and the larger one off to the left when looking down the throat. Pop off should be 36-38 psi with the recommended springs. At 30-psi the carbs flood and won't transition. The ski (GTX) gets stuck at 35mph on won't accelerate. If make a small jump or the impeller gets unloaded the engine will transition and the ski will take off for top speed.

If i hold my finger over the bigger hole in the carb body that is next to the three little ones, i can get a good flow of carb cleaner through them.. If i don't hold my finger over the bigger hole, they will not have fuel go through them. My pop off is right in that 36-38 for each.

 

[Stevie96xp]

Your high speed screws should be at seated all the way down that is factory spec. Also pop off but my guess would be carb settings

 

[Venturian1]

i'm not familiar with the "restriction" you speak of in the return line.

Oops, my mistake. What I previously described is the recharge jet in the feed line to the accelerator pump on my 98 GTS. But there is restriction
in the return fuel circuit on these Mikuni carbs. It's listed in the 88-03 seadoo specs document. Most of the figures are 0.031" and its built into the carbs.

 

[etemplet]

If i hold my finger over the bigger hole in the carb body that is next to the three little ones, i can get a good flow of carb cleaner through them.. If i don't hold my finger over the bigger hole, they will not have fuel go through them. My pop off is right in that 36-38 for each.

I'd say that's a win. Pop-Off spot on. If you have trouble now work your way back to the fuel baffle. I've fought some wars on that end and just finished one. I block the lines closest to the fuel baffle and pressure up the system or pull a vacuum. If I find a leak it is generally in the fuel selector, but there are other issues as well. Good Luck

 

[cloudmaster_321]

Little update to this thread. I've toyed with punting, and selling. Had many low ball offers. Decided to pass on those.

I decided to winterize the jetski yesterday, fired it up, ran on the hose. Then ran on antifreeze. All went well, and ran as normal on the trailer. I decided then, to start pulling components so i could pull the motor to rebuild over the winter. One of the first thing i removed was the exhaust output hose, after the waterbox. Took it out, and water ran out of it. What the heck. I had a stream of RV antifreeze come out of the exhaust, how could this be. The hose was squishy in the middle, and felt like something was in it. I cut the hose in two, and found the hose was separating and coming apart. Not sure how restrictive this was when the machine was running, but certainly not right. I'm going to get a new hose, and install and run the ski on the water again. Not sure if my issue was this all along or not. I just figured since smoke and water came out the exhaust, all was well.

 

[Stevie96xp]

Yeah that would be my bet that is your issue

 

[cloudmaster_321]

Yeah that would be my bet that is your issue

We shall see. I ordered a new hose. Will try it when i get it; and then winterize again.

 

[cloudmaster_321]

Turns out, the exhaust hose was the problem. Runs up to 7,000 RPM's and 50ish MPH.

 

[Stevie96xp]

Good man glad that’s fixed it

 

[tobytd]

Thanks for posting problem solved

 

[burtshaver2021]

Good job Ryan