96 GTX dies at throttle up

[Jgriff687]

Hello everyone, Veiwed alot of the threads but first time poster. I'm sure this isn’t a new problem so I apologize for any duplication.

My 96 GTX (should be totally stock) had a problem in that it will be hard to start. I took the carbs off and other than dirty filters which I cleaned, looked to be recently rebuilt as onside was clean and parts seemed to be fairly new (just got this seadoo about a year ago used). I reassembled, set the idle out of the water at 3000 and set the high mix at 0 and low at 3/4 to begin with. When I took it to the lake, it was a little hard to start but seemed to run fine. After about maybe 30mins -1 hr of slow to full out running, I came to a stop with engine at idle and when I went to take off again it stalled. I could restart it and idle fine but again would stall when taking off. It then became hard to restart and only after a while could I get it restarted and giving it a very easy light throttle, could I get going. After about 1/4 or more throttle, it ran fine. I have noticed that if I let it idle for any significant time it will die when trying to go again. If it doesn’t idle long it seems to be ok taking off for the most part. My impression is that its getting loaded up with gas but hard for me to tell to be honest.

To answer some of the normal ideas given here. Fuel lines have already been replaced prior. Water/ fuel filter up front has been checked. Rave valves recently been cleaned and diaphragms replaced.

I did notice the larger of the jets was like a 135 or something, definitely not what I think its suppose to be (142?). I could not get the smaller jet out as it was stuck and didn’t want to mess it up trying. I don’t know the pop off pressure sorry.

If I understand what I read, the low speed mix and the jet at what primarily run things at this speed.

Any suggestions on where to go from here? Low speed mix out more? Needle valve and smaller jet replaced?

Thanks again and sorry for the book
John

 

[Chris488994]

Have you read your plugs lately?

My 96 GTX runs great with the low speeds set at 1 1/4 and highs Mag 0 (all the way in, lightly seated) and PTO at 1/4. With stock Jets.

It might be leaning out.

Did you check your fuel selector valve for any junk?

Let us know what you find.

Good luck buddy.

 

[bruester420]

Lets start with your settings on your carb.

LOW 1 turn out
HIGH 0 on the mag and 1/2 turn out on the PTO.

Main 142.5
Pilot 70
needle 1.5

These are the factory specs.

 

[Jgriff687]

Did you check your fuel selector valve for any junk?

I haven’t checked it yet but I will. Figured the guy before me who changed the lines probably did that but wont hurt to try.

Ill set the carbs at the factory setting and see what happens. Wont get to it till weds. Cant change the jets as of right now so will have to go with what is in there. Will get new ones to replace those if the problem persists.

I also remember when I looked at the carbs that I noticed around the welsh plug on the mag carb that there was some dry putty like substance in it. I cleaned it out thinking it might be breaking loose and causing issues. Now thinking more could that have been there to stop a leak and be part of my problem? I didnt do any testing of it as I didnt until now know how to check it. Did not see any obvious issues with it though. thanks

 

[Jgriff687]

OK, finally got a chance to try boat. I adjusted the low to 1 and high stayed at 0 for now. Boat would not start. Not even sounding like it wants to try. I pulled the gas return line after the juncture of the lines from both carbs and it’s full of fuel so I think it’s safe to say I have fuel going to and thru the carbs. I pulled the plugs and I do have spark but doesn’t seem very bright. Not like what I’m use to seeing in car plugs. I’ll check to see if it needs trimmed back and redone. The plugs looked black with a light coating of a clear liquid (gas?). These were after my previous running the other day so I know they aren’t accurate to any particular throttle setting. Not sure if this helps any. I’m going to put new plugs in and see if I can start it over the weekend to do a proper plug check. Also going to check oil pump to make sure its setting are correct and I’m not getting too much oil. Any other suggestions?

 

[Jgriff687]

OK Update.... I got it started on the trailer in the water but it took a bit of experimentation of throttle and choke. Seemed to start when I had WOT and full choke. Also seemed to start instantly after initial start without any choke/throttle. Have both carbs low at 1-1/2 and high at 0 for now. Let it idle for several minutes and chopped it. PTO looked almost new with very little discoloration. MAG looked ok but had some oli/carbon fouling I think. I still notice a clear liquid im assuming is oil on the plug end. I also noticed it seem to be missing some and running a little rough. I pulled the plug wires and the engine wanted to die on each cylinder so I know I am running on both. I did a check of the battery before I started and it was about 12.6v more or less but less than 13v to start with. When I ran it up to 5500 rpm it did not move. Im assuming I have a bad rectifier. I pulled the red plug on the rectifier and there was no change in its running. After a long idle I tried to throttle up only to get the same ole hesitation and then run fine. After several times doing this the hesitation would get worse until it would bog till it died. Once it did that I had trouble getting it started to the point where it would not start anymore under any throttle/ choke setting.

Questions...
1. could rectifier be causing all this to happen?
2. with my battery on the low side, could this be affecting my ignition spark?
3. Carb rebuld? (which i am thinking I will need to do if anything to get factory jets back in and make sure pop off and needle/ seat are good.)

Any other ideas are surely welcome. This thing is becoming my nemisis I want to slay lol

 

[Jgriff687]

No one has any ideas? I changed the rectifier and am going to see if it make any difference. Got a feeling I may have a stator out but we'll see on the test ride.

 

[Jgriff687]

new test results

Ok took it out today and started it. Low speed at 1-1/4, High at 0 on both carbs. Let it warm up with old plugs then stopped it and put in new. Idled it or ran below 1/4 throttle for about 15- 20 minutes then pulled plugs. These are what they look like. (see attached pics) I still get the hesitation and bogging when I let it idle for a while. I took the new plugs out and put old back in to play with bog issue. Would bog/ hesitate but if I eased the throttle then it would run fine all the way to WOT. I get 7000 rpm and around 45 mph with 2 people on it.

Rectifier is now new and I attached a volt meter to battery. 13.2 volts stopped. When started and ran it dropped to about 12.8 with it holding at 12.7ish during idle test mentioned prior and a few mid to WOT runs. Total running time about 30 mins or more off and on. I was getting a 12v low warning when I would run it for an extended period of time prior so not sure if I ran if long enough. Do these numbers sound like I have at least that issue taken care of? Not sure when it kicks in to charge the battery. I’m assuming when battery gets to a certain voltage it turns on and lets the charge in. I’m going to do more extended run on Monday to see if it drains battery. I’m not sure what to think of the plugs. The MAG looks fine with the PTO maybe a little rich or oil fouled? Any plug experts out there who can help? LOL thanks John

 

[Young-SC-Owner]

No, it should be constantly charging while the engine is running.
Id be sure to make sure your battery is good.....Maybe your charging system is bad? Thus causing the battery to draw down and cause running issues? Then after sitting the battery "recovers" and lets it run for a bit again?
Just throwing out ideas. When you start your ski, it should have between 13.5 and 14 volts at 3000 RPMs. You can check and see...and post back

 

[djredman99]

I am certainly no plug "expert", but that first pic to me does not look good. I would thing that it is running lean. I see almost no coloring whatsoever on the ceramic inside and the metal arm looks "white-ish".

To me, a nice looking plug has a tan/coffee color to it. If it was my ski, I would be worried to run it too much with a plug like that, afraid to blow that MAG side piston.

 

[poolpumpguy]

compression test and spark test, might be a bad spark plug wire boot. i have had the wire in the boot corrode , it can send ya on a wild goose chase .. ya know

 

[Young-SC-Owner]

To me, a nice looking plug has a tan/coffee color to it.

That is correct in use with a 4stroke engine, but being a 2stroker you need to take in the account of oil being burned,....The plug should be black, but not carboned up with gunk (fouled).

 

[Young-SC-Owner]

Jgriff687,

Your either having carb problems, in turn being a fuel delivery issue. Or if thats all kosher, you may have an intake leak, after the carb. Try adding some 2stroke to the fuel and see how the plugs look.

 

[Ninetok]

I had the same issue. Found out some dummy put the wrong springs in the diaphram arms. Changed them to the 80 gram I think and now she runs like a champ.

 

[Jgriff687]

test results

Thanks for everyone’s input. I took it out today and it seemed to actually run fine. Still had some hesitation/ bog (still can’t figure out the correct way to define those terms) but would work through it by a slow addition of the throttle. To answer a few items brought up by your posts:

1. Compression is supposed to be good. Originally took it to a seadoo mechanic whose prices I didn’t want to pay and he told me in his initial evaluation that the compression was fine. He wanted to just replace just about anything instead of fixing the issues.

2. I cut the spark plug wires back 1/4 of an inch and though spark isn’t as strong as I have seen in cars, it is definitely there.

3. Volt meter showed 13.2 with engine off. Running was at 12.8 that eventually dropped to 12.4. Did not go lower than this while running for almost 2 hours. With new rectifier in it, I'm thinking stator isn’t putting out enough to charge it totally but barely keeping up? Have checked all fuses and all are fine.

I did run it until it ran out of gas (even when I switched to reserve).... or so I thought. Checked gas/ water separator and it had no gas in it but the tank appeared to have some which in fact it still had around 6 gallons as I put another 9 in the 15 gallon tank when I refilled. Cranked the engine to see if the separator would fill but no go. I now am thinking I have a fuel delivery issue somewhere. Fuel pump, clogged in tank pick up screen or air leak in the hoses somewhere. I don’t think its plugged carb filters as this would not cause the separator to not fill as the hoses by pass the carbs if they can’t put gas in and go back to tank right?

Before anyone asks yes all lines have been changed and the selector has been looked at and cleaned. Not sure tank was ever cleaned out as well as in tank pick up as this was a used boat and previous owner had lines done.

I’m assuming that if I’m getting intermittent gas delivery, then that could be my culprit or is this just another issue along with the others? lol

Any other ideas are welcome.

 

[Ninetok]

Go and get some Mikuni kits I know they are high priced but well worth it. Mine was having the same issues and when I put the new kit it it ran like a champ. I used the bigger spring and it made a world of diffrence. I think someone before me used the wrong springs that was causing a rich conditon my plugs looked the same as yours. After the kit they came out dry tan. Hope you get right because mine worried me to death.