1999 GTX Limited bogging and lurching at WOT

[DQuinn]

Hello,

I am new to the world of PWC, at least as an owner. This 1999 Sea Doo GTX Limited was given to me about 4 months ago and ran fine... until last week.

Symptoms:

Motor (951cc) idles fine and doesn't seem to miss.

At part throttle, the motor powers the craft fine, up to 35-40 mph.

Giving it more throttle (close to WOT) the engine will gain RPM up to 5600 then "Bogg" down to 4500, then back up to 5600 and down again. This bogging and lurching happens rhythmically at about 1 second intervals. This problem came on in a matter of hours, getting steadily worse but has since plateaued.

No trouble codes or beeps are noted from the computer.

Found a broken stud in the bottom of the craft, all head studs are accounted for and I cannot find where it came from.

What I've tried thus far

Changed the spark plugs - no improvement

Cleaned the RAVE valves as per forum instruction (Thanks to the author!) - no improvement

RE-assembled the water pressure regulator (the metal band had come un-screwed) - no improvement

Any advice would be appreciated at this point as I am sort of baffled. I am new to PWC but not new to two stroke motors, or mechanics in general, so nothing is out of reach.

Thank you,

Dan

 

[timmyboy76]

carb/s, fuel selector ,and replace grey lines if in there...:cheers:

 

[DQuinn]

Update

While removing the exhaust (not fun) in order to replace the fuel lines, kit the carbs... I found where the mystery stud is from. It was the broken piece of the 4th exhaust pipe bolt which is usually the toughest to remove (according to reading other threads).

My question is can this exhaust pipe "leak" cause the symptms that I have described?

 

[bz1mcr]

If when you say "stud" you mean a bolt with a head on one end and part of the threaded end broken off, then what you have is the same as mine. I have the same "will not run at steady high speed. It lurches back and forth as one cylinder fires for a while and then stops firing (like the ignition was being shutdown). The other cylinder fires continuously. And, I also found a broken bolt in the bildge. It was just laying in the bottom of the boat. The bolt has a 13 mm head an 8 mm shank and the broken length is just over 25 mm from the bottom of the head. Where did that come from?

 

[bz1mcr]

My broken bolt was the one holding the exhaust pipe to the angle bracket on the front of the engine. I do not think it is related to my inability to sustain full speed.
Don

 

[DQuinn]

Problem solved

After many setbacks, including filling the motor with water, I have put the Doo back together and successfully ran up to WOT with out problem.

I removed both carbs and rebuilt them both, which is actually quite easy once the carbs are removed. The internal filters were plugged pretty good and I do not think enough fuel was getting through.

I also replaced all the gray fuel line with new, black fuel line. If you are about to do this project, take a sample of the line with you to the auto parts store to match it up. Sea Doo uses a metric size fuel line which will be hard to find. I ended up using a close match SAE line.

The external fuel filter as well as the water seperator were also changed.

Just writing this to help others who may have the same problem.

Thanks to all for your imput and help, Good on you!

 

[bz1mcr]

Thanks for letting us know. I gave mine to a mechanic, but so far it sounds like it is going to turnout a lot like yours.
Don