2000 gtx stalls

[chefguy]

Ok. With a little help reading here i was able to fix my 98 gsx.Starter gear assy...Thanks guys..
new problem with my 2000 GTX w/ rotax. We had issues with the plugs fowling this spring went to a hotter plug. Now it stalls out at 50-55 MPH. consistently. it will start immediately after stall and as long as you stay below that speed no issues my dad rides it all day. But if you try to get top end out of it it will bog down and stall. seems like fuel... I have checked the fuel filter it is ok. really stumped... Any thoughts?

 

[seadoosnipe]

Welcome back!

I'm glad the forum was able to solve your last problem, lets see if we can help you out again.
First, when you come in, gather as much information about your PWC as you can. There are 3 models of the GTX for that year, the 5653, 5648 and the 5515 and 3 different engines, the 717, 787 and the 947.
Let me see if we can look at it generically first. If it runs fine except it won't hold top end, I would think it could be a couple things. Here I'd have one more question first, when you apply full throttle, does the engine first accelerate to maximum RPM's and if so, your saying when you go over a certain speed, it shuts down on you?.....I'd first suspect fuel pressure or a lack there of. Then, the PWC could be shutting down if your leaning out with the higher speed (upper end torque), and third, depending on what model you have, incorrect throttle position sensor........
My first bet, if it's running smoothly through all the other ranges but top end, would be on a drop in fuel pressure.....

 

[chefguy]

it has the 951 rotax engine. I can ride it at all ranges no issues ..only when i push it to full throttle ...it reaches about 54 miles per hour then cuts out. what would cause it to lose fuel pressure only at 54 miles per hour? it has been a great machine.. we have had no engine problems with it till this summer. could the rave valves be sticking?

 

[seadoosnipe]

Rave Valves!

I don't think so. Depending on if they were stuck open or closed, they won't let the engine operate at peak efficiency, but they shouldn't shut the engine down.
I'm at work right now, I'll do a little more research when I get home tonight with the new info you provided..........