2000 GS 717 runs out of fuel pressure after 40-60 minutes

[carlspeed]

Hello all, I'm hoping I can get this fixed before the end of my son's summer vacation. I don't understand how the fuel system works in this engine (2000 717cc motor) to be able to really diagnose this. Basically, I got the ski after it had sat for like 6 years. We cleaned the fuel tank, checked the lines, and did the same with the oil tank. The lines appear good from the outside, no leaks, cracks, still soft, etc. I checked the carb and it was flowing fuel well. We took it out, and it ran great. So nice, good bit of power surprisingly, and we had a blast on it. Ran it for about 45 minutes or so, and it starting stalling out. It wouldn't die, but it was clearly running out of fuel. Fuel was not going into the inline filter fast enough to get into the carb, and you could see with the seat off that under 2/3rd throttle or more, the inline filter would dry up before enough fuel accumulated to keep the rpm going. If you hold the throttle down, it will stall. If you let off when it starts to die, it would idle without issue at all. After a second or two, you can go back up to 2/3rd throttle, but no more, or the same problem happens. Anyway, I thought maybe there was a bad vent, so I tried to run it without the gas cap, and that was worse. I got home, read that the fuel tank runs on a pressurized system from the carb, and it needs pressure to go. I replace the inline filter and the fuel water separator, and we go out again. Like the last two times, runs perfect, 50mph on GPS, etc. After 40-60 minutes, it starts running out of fuel. Something is happening at that time frame preventing the tank from flowing fuel into the carb. Again, I understand fuel, but most gravity and fuel pump type stuff. If this is really pulling pressure from the carb I don't understand how it works, and if someone can explain it to me I'm sure I can get it going. Thank you so much for any help in advance! I'd be happy to send some cash to anyone who can help to get you a few frosty beverages for your time. Thank you!!!

Edit: Also, the fuel has always been over a half tank.

Carl
2000 Seadoo GS 717cc motor single carb

 

[JJinSC]

It sounds like your fuel vent is clogged. That will cause a vacuum to be created on your fuel system and cause your symptoms. Opening the fuel cap will equalize the pressure. You will probably hear a hiss from air rushing in when you crack open the fuel cap. Clean replace your vent line and also check the pressure relief valve on that same line to make sure it is functioning properly.

Edit: disregard. I see where you already checked that. One thing I would suggest right now is remove that inline fuel filter.

 

[JeremyD615]

The fuel pump is built into the carb, and is a vacuum operated diaphragm system. The fuel is pulled through the lines from the tank rather than being pushed by a standard pump.

So the first thing you need to do is replace all of the fuel lines if they are still grey factory lines. Even if they look good externally, they are not compatible with ethanol fuels and the inside coating melts into a green goo that plugs everything up.

Second, get rid of the inline filter. They are no better than the factory separator, and cause problems more often than they help.

You’re probably also going to have to rebuild the carb(s) using only genuine Mikuni parts. NO AFTERMARKET!! Follow the carb rebuild sticky and you should be good to go.

 

[carlspeed]

Okay sounds good. I've been trying to get in touch with OSD to figure out what size fuel and oil lines I need for an entire job, but I have not been able to reach them. Do any of you know what sizes and styles / lengths to buy? And from where? I was also told something about check valves in the tank pickup assembly. My fuel gauge doesn't work either, so if I do that I'd like to fix it all at the same time if possible.

Thanks again!

 

[JeremyD615]

Your fuel line is 1/4”, and you should use regular black automotive line from the local auto parts store. You’ll need about 25ft.

The oil lines that need changed are the 3/32” tygon lines that go from the pump to the manifold. Leave the larger lines in place unless they are leaking. You can get these from OSD, or a hobby shop that deals with RC cars and such.

Check valves you can get from OSD as well. He normally keeps those on the shelf, and he has the repair kit for the fuel float as well. They may be closed for vacation, but if that’s the case, they’ll reply via email in a day or two.

 

[carlspeed]

Thanks! I sent them an email Friday I think of last week. Would like to order from them but I still haven't heard back, so I'll probably get everything elsewhere.

 

[JeremyD615]

I think he’s a one man shop there, so he takes some well deserved time off on occasion... I will tell you their customer service is amazing when they’re open though...

 

[carlspeed]

Totally get it. Just need the stuff asap so I can try and get it fixed before the little dude goes back to school.

 

[JeremyD615]

Well I would try Westside Powersports next if you haven’t already found a source. You’ll have to call rather than order online, but they know their stuff and will give you genuine OEM stuff...

 

[carlspeed]

That's my current plan. I messaged Jess and he said he should have everything in stock. Calling him in the morning.