GTX Fuel Issues... what comes next? "long"

[gsxkydd]

Want to say hello to everyone first as I just entered this sport last week as well as this forum. Thanks to JPX, KustomKarl, and SeadooSnipes for all the previous info I have already used to help me troubleshoot this problem.

Bought 96 GTX last weekend from a very honest guy I knew previous to purchase who owned it 10 years. He has top end rebuilt about 4 years ago he said and had the guy leave the oil screw out a bit so it wouldn’t run so hot and lean and be more reliable. Every season since the first time in the water it would bog or seem to load up so his resolve was to restart with WOT for 1-2 seconds and then it would run fine. He showed this to me when I test rode as it was the first time launched this season. It worked great and I proceeded to run it as hard as I could for 20 minutes to make sure it ran smooth.

First time I put it in the water the problem got so bad I couldn’t WOT at all. Would start bogging after 3-4 seconds of WOT and get worse every throttle 5k, 4500, 3500, ect ect. I have since replaced correctly gapped plugs, cleaned fuel filter, cleaned rave valves, removed together and cleaned filters in carbs, cleaned fuel selector valve and replaced all grey lines outside the tank.

Problem has become less often but still frequent when selector is “ON” position more then when its “Reserve”. When on “reserve” after a minute or two I could get it to run WOT at 49mph, 7060 rpms as well as vary the throttle at any rpms with just a small misfire still at 4k but will increase right past it no problem. Idle is a little low I think at 1300rpms. I pulled selector apart using small set screw but didn’t know if maybe they can go bad (rubber inside them or something). Also tried to remove in tank unit but couldn’t get it loose even with both clamps removed. Is there something in the tank that could cause this… maybe something with the “ON” in tank line. Also when I cleaned the RAVE valves one is newer with two grooves in it and a green rubber baffle where the other is flat with no grooves and a red baffle. This one was completely clogged and wouldn’t open at all with baffle half off when I cleaned them they are both moving freely. Which should I have?

Sorry this is so long, I never post on forums but wanted to state everything and see where to go from here. Thanks for all the help already this forum rocks!

 

[seadoosnipe]

Fuel baffle.....

What are the position of your set screws on your RAVE's. If not all the way in, try that.

On the mag carb, you should have 3 lines. The line in the middle is going to the engine block, this is the pulse line. The one on the bottom is your fuel from the tank. The one on the top is the fuel return line. Take that line off and see if you can blow through it.

Repost...........:cheers:

 

[gsxkydd]

Raves valves are flush. I unscrewed the red caps marked one slot on each and screwed back in flush and equal on both. I will try turning them down hard.

I pulled the carbs out together hoping to leave them in sync. Seeing the trouble with those dumb clamps I was able to buy a few clamps at Walmart to put on the grey lines between the carbs while they were out so I could replace those small lines anytime while in the ski later. Napa was closed and I couldnt wait to try it with the filters cleaned so I replaced the new clamps and cleaned the small grey lines coming from the platstic "T" and the black rubber line going into the engine block which I think you are calling the "pulse line". Today I purchased and replaced all other lines except those little grey ones on the carbs. This would include both lines from tank to selector, selector to filter, filter to mag carb, "T" return line to tank. and tank vent I assume as well.

What rave guillotines should I have, will the grooves in one and not the other make a difference? Thanks

 

[gsxkydd]

I had a chance to turn in the red caps all the way today on the Raves. I had a little bit more throttle response up until around 4k rpms where the bogging begins. It idles fine but to get it to rev past 4k I have to restart it and then I get one or two rev outs 3-4 seconds each before it bogs again. After about 15 restarts it will come right up to speed randomly and I can run it at any speed including WOT for a bit then it will suddenly bog again. I did lose about 3 mph and 300 rpms with the caps screwed all the way down.

Like I mentioned before I have one that looks to be newer green rave rubber piece and one older red one. The red one will not stay on even if I change to a tighter spring clamp/tie. It keeps coming right off and jamming that Rave somewhat open. I order new rubber cups from SBT.

Could this completely solve the problem? And again is it a huge deal to have one guillotine with grooves and one without. Thanks

 

[seadoosnipe]

RAVE's......

Yes, there are different styles of the guillotine valve made for the cylinders of the Rotax engines. You must have the correct slide valve (guillotine) in for them to work properly. The reason you popped the bellows is because you built up to much pressure behind it, due to the slide vavle not working properly.

When the engine is running and throttle is applied, the pressure in the exhaust system is what pushes opent the slide. When that happens, that pressure is relieved by exiting the heads through the tuned pipe.

So yes, to answer your question. The wrong slide valve will cause your problems.:cheers:

 

[gsxkydd]

Since this properly started about 4 years ago the previous owner said right after he had the top end rebuilt I'm guessing the newer green rubber with the grovved guillotine is the incorrect one. Maybe that one broke and cause the motor to fail. Is there a way to find out which guillotine is the correct one for 96 gtx.

Also have been following another fuel thread closely as I too think my selector valve is no good. I did clean it out but I was leaning toward it having some kind of rubber inside the valve as it didnt go back together very easily and I think that is a problem too. It will run randomly in "ON" or "reserve" but its funny as the more I play with the valve the more random it gets. Will run a direct line and check the pulse line again once I install the new rave parts.

 

[Dennis]

rave valve

SEADOO came out with a updated rave valve and bellow ( green rubber thing)
a few years ago. The old style bellow was black and the old style valve had NO groove in it. The NEW style bellow is green and the NEW style valve has a groove in it and is supposed to be more durable. Some old style valves would break and fall down on top of the piston causing severe engine damage.
DAWG

 

[gsxkydd]

I have one green bellow paired with a grooved valve and one red bellow(the one that keeps coming off) paired with non-grooved valve and looks much older. So the grooved one is just a newer model but will still work with my 787 engine correct? If I replace any valve it should be the older more worn one then so that I have two grooved ones correct?

I also seem to have a good amount of oil blowing past the old worn red bellow, thought it was because the previous owner had the oil injection high. Is this oil blowing past the rings or something, I will have my compression tester this weekend to check on that cylinder. Is it normal to have oil leaking there if the bellow has come off?

 

[gsxkydd]

I did get the old red bellow to stay on the rave valve using a tighter spring clamp... they both move freely up and down with no problems and no jamming. I also checked the water injector on the exhaust for cooling(brass fitting was clean).

Bypassed fuel selector/ect. by running line from tank to fuel filter straight to carbs. Cleaned and reinstalled pulse line with new clamps, as well as readjusted mid carb setting. Still have the same bogging/sputtering at 4k rpms after one or two revs of the engine.

I don't think I missed anything on the troubleshooting checklist, so I am looking either at something clogging in the tank itself or maybe I have spark cutting out at higher rpms? Checked all wire connections and looked in the black box in the back to make sure there was no moisture in there. Whats next as I will soon have all winter to work on this thing!

 

[seadoosnipe]

Plugs?....

What do your spark plugs look like?

It sounds like you may have the carbs out of sync. You may need to remove the air box and take a look, do some tests to see if they are synced.:cheers:

 

[gsxkydd]

I will look at the plugs tomorrow when I get a chance. They are new as of three days ago. I had the carbs off together when I cleaned the filters in them the other day. I didn't move the rod or anything that connects them. Today I did just the mid speed settings out 1 1/2 turns on both and lined them up as good as I could using a mirror. I'll read up on syncing the carbs as I have the airbox and everything off right now.

What I don't get is how random it is. For example yesterday when turning in the rave red caps I sit in the water with it bogging for 4-5 minutes trying everything from fuel selector positions to restarting with WOT to slow acceleration, and then just one of 20-30 revs it just goes right past the bogging point of 4k and takes off.... will run like that anywhere from 10 seconds to 10 minutes at 50 mph. Sometimes I can't get it to bog again for 10-15 minutes straight no matter what I try with stopping and starting and slow acceleration. Shut it off and restart it an hour later and same thing.

 

[derek]

back to the origional question. the fuel pickups. there are anti-siphon check balls in the bottom of the fuel pickups. they stick fully or partially shut. pull them out, carb cleaner them up.; you can usually get them free.

 

[gsxkydd]

Derek,

Are these check balls directly under where the four fuel lines go into the tank. I did read about the check balls/in tank filter but after watching a video showing the in tank unit I thought it was just a unit for the fuel gauge(that little magnet that falls off showing fuel low) so I figured those check balls must have been for another ski. I attempted to get that off the other day when I replaced the lines but even with both clamps completely off I couldn't get it loose but I'll try again.

I'm leaning towards electical/ignition now maybe just because I'm running out of fuel otpions. Just seems like once it does run WOT then it will just cut out and reproduce the same symptoms like an electrical part going bad. I'll finish up the fuel issues first to make sure. Thanks

 

[gsxkydd]

Seems like after chasing all the fuel issues down (still glad I did all that) as of now I am 99% sure it is a bad rectifier. I was able to pull the 15 amp fuse for the rectifier and ran it on the trailer and it revved up freely each time, I then ran it on the hose for about 5 minutes and still revved freely no bogging until I plugged the fuse back in while the ski was running. Immediately dropped about 200 rpms(enough to hear a difference) and would bog just like normal. Took out on the lake and ran the crap out of it for about 6-8 minutes and couldnt get it to bog once with the fuse out. Soon as I put the fuse back in it starts the random bogging again.

Someone once said the rectifiers are hard to diagnose with a voltmeter because sometimes they only break up higher up in the rpm range. I will be ordering one tomorrow.

My last question for now is, how long can I run the ski without the rectifier? Reason being that this weekend is the one weekend I wanted to run the ski the rest of the summer. Didn't know if the rectifier did anything else besides charge the battery. Is the battery only used for starting or is there a draw the whole time. Thanks for all the help!