Super Jet SN 650 random dying issue

[Sandeggo]

I’m chasing a random dying issue. I get a minimum of 30 minutes ride time before it happens. I’ll ride for 30 minutes, and the ski will shut off. At first I was thinking electrical, but I have also been able to squeeze the throttle and power out of it occasionally. When it stalls I can usually restart it while sinking. Last river trip I took apart the start stop switch, cleaned it and regreased it. Changed the check valve, and removed the heat sensor, and changed the plugs. Water separator was bone dry. I also changed the fuel filter. Went on a ride for about an hour and a half and had zero issues. That afternoon thinking I had solved my problem, we went down river and 30 minutes in, it stalled. Every time it stalls I get less and less run time on the restarts until it’s stalling every 30 seconds or less.
I replaced the start stop harness with an OEM harness.
Went on another ride, 30 minutes in it bogs and dies. Got to my buddies house on the river and BS for about 15 minutes hoping it cooled enough to ride another 30. The motor is not hot at all. I can put my hand on it no problem. Start rising back and it dies within 30 seconds. While riding one of the times I tried choking it slightly and it immediately died. Every time it dies it gets harder to start. Right now I can go in my garage, barely touch the start button and it fires up without any throttle or choke. The ski runs great in all rpms for 30 minutes of fun.
I have a stator that I’m going to try and while it’s apart I’m going to pressure test, but I’m not sure if it’s electrical or fuel related now. I replaced all the lines with transparent lines and I’m noticing some bubbles in the feed line, should the be solid with gas?

 

[e46erak]

Sounds like an exhaust leak, your engine bay slowly builds up with fumes and makes it difficult to run (lacking oxygen). Check your lines and hoses to the waterbox especially.

Make sure your tank check valve is orientated correctly (air should flow into the tank)

 

[Sandeggo]

Sounds like an exhaust leak, your engine bay slowly builds up with fumes and makes it difficult to run (lacking oxygen). Check your lines and hoses to the waterbox especially.

Make sure your tank check valve is orientated correctly (air should flow into the tank)

When I pull off the hood and let it air out, it’ll still stall after. It won’t go good for 30 minutes until it sits for hours. The check valve is oriented correctly and functioning as it should.

 

[e46erak]

Carb could be leaking excess fuel while running causing it to slowly flood until it evaporates after sitting for a while?

 

[Sandeggo]

Carb could be leaking excess fuel while running causing it to slowly flood until it evaporates after sitting for a while?

That’s a good possibility. I have a Mikuni kit I can throw together. Thanks.

 

[550headache]

Check the small fuel filter in the carb on the diaphragm side. When they get clogged it will do exactly what your describing.
Good luck!


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[Sandeggo]

Check the small fuel filter in the carb on the diaphragm side. When they get clogged it will do exactly what your describing.
Good luck!


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I got a kit but been waiting to do it since my research was telling me it may be electrical, and the previous owner said he did the carb. I’ve only had the ski a month.

 

[be_lain]

Could be fuel selector switch. Try bypassing it to see if it still happens. This happened to me while on the face of a wave (!!!) and after chasing the issue for a long time it ended up being a bad fuel selector.

 

[Sandeggo]

Could be fuel selector switch. Try bypassing it to see if it still happens. This happened to me while on the face of a wave (!!!) and after chasing the issue for a long time it ended up being a bad fuel selector.

I took it all apart and blew it all out. Oring looks good.

 

[mthomps]

Does it bog down and die then won't start or is it like someone yanked your lanyard off type of shut off? Will it fire then can't get out of its own way or no fire and an endless cranking?

If its a bog I'd start carb and tear it apart, note the shape of the diaphragm and needle and seat. Needle and seat does not come in a rebuild kit. If needle is worn in any way replace it. Stock is 1.5 for NS.

Otherwise inspect all ground and positive cables. Any sign of wear replace. Look inside and outside of ebox. Note If ebox is wet inside fix that problem before you ride it again. You said you are swapping stator?

Inspect plug boots. Detach and cut back if there's any doubt. Replace voltage regulator.

 

[Sandeggo]

Does it bog down and die then won't start or is it like someone yanked your lanyard off type of shut off? Will it fire then can't get out of its own way or no fire and an endless cranking?

I would say it’s like a lanyard pull mostly. It usually makes my chest pop my chin pad loose at the clip lol. The first few stalls I can fire it while sinking and still standing in the tray. It gets progressively worse until it will crank for about 20 seconds before it fires. Everytime it stalls there will be less and less run time before it does it again.

If needle is worn in any way replace it. Stock is 1.5 for NS.

I was shopping for one but wasn’t sure of the size. I plan to replace it anyways.

Otherwise inspect all ground and positive cables. Any sign of wear replace. Look inside and outside of ebox. Note If ebox is wet inside fix that problem before you ride it again. You said you are swapping stator?

Inspect plug boots. Detach and cut back if there's any doubt. Replace voltage regulator.

I was inside of the Ebox over the 4th swapping parts back and forth to diagnose a no spark issue on his 91. We were able to diagnose his as the CDI. The Ebox had some moisture inside it at some point as there was slight corrosion inside. Nothing major, but enough white dust to vacuum out of the bottom of the box. Put dialectic grease on all the connections when I put it back together.

 

[Shreditor]

I had one do this due to an air leak on the carb plate causing the fuel pump to run dry. Couldn't figure it out forever until I finally replaced that plate. Best of luck, it's always fun trying to troubleshoot these things..