5,000 RPM Maximum on 1996 GTX

[gtxnoclue]

After running decent for the last few years I once again have an issue with not being able to run anything over 5,000 rpm. The forum has been a great resource in the past & wondered if you might come to my rescue again. Sequence of events & symptoms below.

I cleaned (but did not rebuild) the carbs and it ran great for a few outings. After about 3-4 good rides it started capping out at 5,000 rpm.

I then replaced the fuel selector switch, replaced the gray fuel vent lines with black fuel line (remainder of fuel lines had been changed ~8 years ago), and installed a new pressure relief valve as well as check valve for the fuel system. Still had the same issue.

Checked the voltage regulator - was only getting 12.7 volts when at 4,000-5,000 rpm. Replaced the regulator with an OEM part, now it gets to 12.8V. Read where it should be between 13.4-14.8.

So not sure what to do at this point. Cleaned the rave valves last year. Fixed a broken pickup coil in August of 2014. Any ideas on what would cause the symptoms described (including what would cause lower than expected voltage at the battery at 5,000 rpm with a new voltage regulator installed)?

Thanks so much for your help!

 

[soccerdad]

Do you know what the compression is on each cylinder? If even and ~150 PSI, then I would open up the carbs again. Maybe something came through from the fuel selector. What did it look like when you replaced it? Lets see. Its either air, fuel, compression or electrical..... So just fix all of those... But seriously, check compression and report back. I assume you plugs look OK? Does your water regulator look OK?

Do you ride at lake Hickory? Never ridden there but it is on my list.

 

[gtxnoclue]

Didn't think it potentially being a battery issue since the seadoo has been starting up with no issues at all. Pulled it out & the charger says it was only about 43% charged (~12 V). Would a bad battery or low charge cause the symptoms described? Will try again after its fully charged. I'm sure I won't be that lucky, bUT you never know. Any advice is appreciated!

 

[gtxnoclue]

Just saw your post. Thanks so much for the info. Yes - actually have a home on Lake Hickory, but don't enjoy it enough. The fuel selector had a 1/16 inch piece of rubber in it. Didn't realize how hard it was to turn until I put the new one in. So I know it was an issue. Was actually surprised when the problem was still there. I'll check compression. Last time I checked (last year I think), both were at 148. Just replaced the plugs (after my post). I think they looked OK - normal to me. Not sure what I should look for on the water regulator - advice would be appreciated. Is it normal to get only 12.8V at the battery with it running?

Air, fuel, compression, or electrical - at least that narrows it down for a novice like me... ; ) I get excited when I can actually fix 1 thing...

Thanks again. I'll let you know about the compression.

 

[gtxnoclue]

Well - I was way off. Took both plugs out, grounded the caps, & the front was 124 & the back was 122. The battery had been charging for a while & maxed out at 65%. Off to get a new battery then will test compression & the voltage regulator again. Thanks for the advice!

 

[gtxnoclue]

Bought a new battery - Super Start ETX16L from OReillys. Compression on both cylinders is 130. Test of voltage regulator still shows 12.8 at the battery.
* Is 130 compression OK being that they both test even?
* Should I try riding with the red wire to voltage regulator unplugged?
* Is there something I should look for with the water regulator?
* Anything else to check or is it time to do an actual carb rebuild?

Thanks again for all the help!

 

[1983]

unplug red wire and go ride, make sure new battery has at least a decent charge on it for this test. system will not be being charged, just a quick ride to vreify yes or no problem is fixed.

water regulator diagphram could be pierced and leaking water, will cost you a few hundred RPM but wouldnt restrict you to 5k rpm.

lastly, only do one test/repair at a time, you want to ultimately determine why this is happening.

 

[gtxnoclue]

Lost momentum & focus on the Seadoo as we just had our oldest graduate from college - Woo Hoo!

After a new battery got us out on the water (mostly my 16 year old son), performance hasn’t been that great. Initially it was ok at high rpms, but seemed to lose power at the high end over time. Seemed to also get worse each time out. Last time out 5,000 rpm was the max he could muster. Thought I needed to check the high speed adjustment screws. As I was taking the carbs off, noticed that the mag carb was loose (1 of the female threads that the carb attaches to was stripped out). When I removed the carbs, noticed that the mag gasket was extremely dirty where the PTO side was pretty clean (see attached picture). I assume having a carb that loose would impact performance at high rpm.

So now on to the fix. Below is what I plan to do based on reading several posts on the forum. But I would love it if someone can verify or let me know where I’m headed for trouble.

Looked up specs for my 1996 GTX. Bought a 8 x 1.25 helicoil kit & 21/64 inch drill bit. Once I find a low profile drill to use I’ll drill out the hole (will measure & use tape to ensure I don’t go too deep), tap it with the helicoil tap, insert the helicoil as deep as I can get it, then use the original bolts to reattach the carbs.

A couple things I still need to research a bit:
• I’ve seen some posts that talk about breaking the tang of the insert – need to find instructions on how to do that (plus ensure I need to do that).
• The inserts are ~1/2 inch in length (~12.7mm). I’ve read a post about using 16mm inserts. I assume the 12.7mm inserts are reliable?
• Use of Loctite 242 or Permatex Blue Threadlocker (OReilly’s had Permatex so I bought it) when I insert the insert (is it needed?).

Confirmation or redirection would be appreciated. Thanks so much!

 

[gtxnoclue]

Still having high end rpm problems after getting the one bolt hole heli-coiled for the carb bolt. From standstill, it immediately goes to 5,200 rpm then slowly climbs to a max of about 5,800 rpm.

Did notice that the water regulator was leaking bad from under the cap. Also noticed that there is a slight tear in the exhaust hose between the exhaust pipe & muffler (I've read that the leaking may have caused overheated exhaust which may have ripped the hose). Going to take the water regulator off to see if there is anything visually obvious. Will also order the exhaust hose to get it replaced as well.

Good advice, 1983 - should have listened from the start & worked on 1 thing at a time. At this point it sure does seem like one thing leads to the next. When will it stop? ; )

Thanks!

 

[gtxnoclue]

There was a big tear in the bellow. And a rusted out metal clamp that holds the bellow to the housing. The largest piece that came off was about 1/8" in length. Will order the parts now. Hope it solves the rpm issue! Thanks for the advice.

 

[1983]

Yup I knew it was water regulator. Plus the exhaust hose leaking is actually a bigger issue than WR. You are inducing exhaust fumes into air intake of engine which kills the engines power.


Rob

 

[gtxnoclue]

Just replaced the exhaust hose between the exhaust pipe & muffler & put a new bellows in the water regulator. No more leaking from either! Had a limited amount of time on the water, but most times I gunned it from a standstill, it immediately went to ~6,700 rpm, then went to ~6,100 rpm before climbing back to ~6,400 rpm. Seems like it was running like it used to. Problem is, it didn't seem to do that 100% of the time. Several times it would immediately go to ~5,500 rpm then climb. Not sure what might cause it to not react the same way every time. Will spend more time riding it tomorrow & Sunday to give it a good test. Any ideas would be appreciated.

On a side note, after riding it for about 20 minutes, I noticed a little water on the engine itself, on the carbs, & on the air intake. While it was on the trailer but still in the water took the seats off to see if I could find a leak from somewhere, but didn't see anything. It may be normal, but don't remember seeing water after riding it in the past (but then again I wasn't really looking).

Thoughts/comments about the intermittent takeoff rpm & water would be appreciated. Thanks!

 

[gtxnoclue]

Well - about to give up at this point. Ran great for a few hours. From standstill, went to 5,400 rpm then climbed to 6,400 consistently. Good speed. Let it sit a few hours. My son then took it out & said it started running poorly. Would only get to 5,200 rpm max. Not sure what to do now. Any ideas before I try to sell it as is? Thanks!

 

[soccerdad]

Sorry it is such a pain. Did you try unplugging the red wire from the regulator/rectifier in you front electrical box? A bad voltage regulator could easily do what you are seeing and does it inconsistently which will drive you nuts. Do that test first. If that is not it, you could now be having a fuel delivery problem. Either the carbs are dirty again or you are sucking air. The air is the easier one to check I guess. Still a little pain though. The test that will take all the factors out at once would be to run a new fuel line from the RES spout on the gas tank manifold directly to the inlet of the front carb. (where the current line attaches). This will bypass your water separator and fuel selector switch which both can be sucking air. Do that test and report back.

 

[gtxnoclue]

Thanks, soccerdad, for the quick response, guidance, & for calming me down. Although it's actually been fun working on it, frustration has just built up as we seem to fix things over a long period of time but never seem to make much progress.

Went to put it in to unplug the red wire & my son noticed that there were 2 bolts missing where the head pipe assembly connects to the exhaust manifold. That answered the question about where the water was coming from. Figured if the hole in the exhaust hose was bad that this needed to be fixed as well. Found the bolts in the hull & replaced them with new lock washers (will Loctite them in now). Put new plugs in & my son said that it's running better now than it has in a long, long time. From standstill, it went to ~7,000 rpm. The whole family is holding their breath, to see how long it will run well (it was just a quick test). Never did unplug the red wire, but I know where to start when it acts up again (I just hope it's not for a few years).

Thanks again for all your guidance & help! And send a post if you ever do make it to Lake Hickory - would love to show you around the lake.

 

[gtxnoclue]

Well - the saga continues. The next day had to tow my son back in. He said it was riding great then the rpm's went way down & he heard a "Grinding Noise". Just now put it in the water to try starting it so I can see/hear what's happening. It turns over but won't start (although it occasionally did start then die after a few seconds). It sounds "rough" to me but I didn't hear grinding. My son thinks an odd sound is coming from near where the stator is located. How in the world do I troubleshoot this with the least amount of effort? As usual, your advice is appreciated. Thanks!

 

[soccerdad]

That sucks... Pull the plugs and try turning it over by hand using the PTO flywheel. Try to find out where it is scraping, front of motor or pump. If you can't spin it over by hand, then you may have to pull the pump. Then, if you still cant turn it over, the starter may be hung up or something is amiss in the stator area. If he is pretty sure it is in the stator area, then I think you will have to go in deeper. I have never done a stator with the motor in. Hopefully someone else will chime in.

 

[gtxnoclue]

Finally had some time to get back to it. Pulled the plugs & turned the PTO flywheel by hand. It seemed to turn fine in both directions (although I don't know what "Normal" feels like). But it definitely didn't feel like anything was binding. Also, did not hear any grinding/scraping noise in the front or back. Did hear a slight "metal clanking" noise when the pistons were in the downward position (maybe connecting rod bearing?). Wondered if it's typical to hear a slight noise like that. With a small rod riding the top of the piston, my son felt like 1 piston (rear) lagged in the most downward position before changing direction. I didn't feel the difference but he's got a pretty good feel when it comes to this kinda stuff.

It still turns over but won't start. We did test & saw spark on 1 plug.

Wonder if I need to step back from the original "heard grinding noise" comment to help with troubleshooting. We discussed it again & he said it was running great then rpms went down to 6,000 for no reason then he heard a noise & then it cut off.

Not sure if I'm in over my head at this point. Definitely don't mind trying, just don't know how to troubleshoot or where to start.

Thanks again for all your help.

 

[gtxnoclue]

Just checked compression. 120 on the front. Leaked down to 90 in 12 seconds. 40 on the rear. Not a good sign. Not sure how extensive fixing it at this point is. Or how costly. Any ideas/recommendations? Thanks

 

[Coastiejoe]

Likely a top end rebuild will solve the issue. Common and cheap.

That said, if you have or are approaching 300 ish hours on the crank, then doing a top end doesn't make much sense.

Reason is, top end is so strong the bottom end fails shortly thereafter.

 

[soccerdad]

Well that sucks. Sorry for the problems. You can easliy pull the head off and look at the top of the pistons. That will tell you a fair amount.