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I purchased this 99 GPX 760 last year and it wasn't running. The compression was good and it had spark so I figured rebuilding the carb would do the trick and it did. Ran it some last summer but not a lot and more early this summer and it ran great. This last trip it stopped on the water while my daughters where riding it. Had compression and spark so I figured must be a carb issue again. Pulled it apart and there was mostly water in the "float bowl" (I'm more of a dirt bike guy, not sure what they call them on these but where the gas is pumped to and where the float needle is). I thought it was odd and figured a little may have accumulated. I cleaned the carb, primed it and it fired up but would only burn the prime. It was as if no fuel was being pumped into the carbs. This was on the trailer and no hose water hooked up to it. Checked all the usual suspects for fuel supply and found no problems. Pulled the carb off a second time and it again had water in it. I also noticed that the intake manifold had what looked to be a light coating of white creamy foam on it, like when water is mixed with oil.

It sure sounds to me like I must have water in the fuel tank but in modern times that would be surprising, at least out of a station gas pump. So, my question is, is there another way the carb could be getting water in it other than pumping it from the tank? We weren't (and haven't been) riding it in really rough water or wildly, more kids and friends just tooling around. We've really have had very little water ever accumulate in the hull at all. Has anyone had a head gasket leak and water actually made it's way up into the carb? That would surprise me but maybe. Also, having tracked all the lines coming out of the tank the vent line looks like it is designed to also catch water in the plastic white "bottle." It was bone dry. What does it do and how does it work (I assume it's for condensation from the tank)?

My plan of attack at the moment is to thoroughly clean the carb again, pump all the gas out of the tank and replace it with new gas but wanted to check here and see if anyone more familiar with these has other ideas.

Any input or suggestions would be greatly appreciated.

Thanks!
 

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My thought is either one of 2 possibilities. 1) the fuel cap was loose allowing water in when running no wake zone or slow speeds. Or, 2) you have a bad seal on the cap allowing above scenario.
I know of no other way for water to get into the carb other than through the tank.
 

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Thanks for the reply Dave. As high on the hull as the fuel cap is I find it hard to imagine water got in there but I too can't think of another way for water to get in the carb other than from the tank and, unless I got some bad gas (again, not all that likely these days) you scenario seems like a reasonable one. I did have that happen once on one of my stand ups but I forgot to put the gas cap on at all! Please don't tell anyone. Do you know what the white bottle on the vent line (at least I think it was on the vent line) does or how it works or does anyone that might read this?

If someone has any other input I would appreciate it. For now I will go through the carb and next week when we go back to the lake (3 hours away, brought carb home, ski is there) I will install it, get all of the gas out of the tank, put in new gas, cross myself and give it a go.
 

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The wht bottle on the vent line is a filter/water separator. There is a thumb screw on the bottom to drain it.

If there is that much water in the tank the fuel filter should show it. They are also a water trap by design.

The fuel cap on my GPr is quite high as well. At low speed its often under water riding 2 up especially.
 

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Discussion Starter #5
That white bottle was dry, like really dry. It is also on the vent line (I'm pretty sure, again, ski is not here). I am more familiar with Kawasaki stand ups and they all had a water fuel separator and filter combo mounted to the side of the hull where the fuel went in one side and the out the other and the water was captured in a semi clear container that screwed onto the bottom of it that. It held about 8 oz I would guess. You unscrew it every so often and dump it out.

Looking at the parts list for the Yam GPX 760 it appears to me that the inline fuel filter is also the water separator. All the fuel goes through it but the water does not pass through the element and collects on one side of the filter. At least, from what little info I can find on them (mostly that they are called filter/water separator and then reading how filter/water separators work) that is what I gather. Giving it more thought, I think the white bottle is on the vent line and is there to take the moisture out of the air that is vented into the gas tank to displace the fuel as it is pumped out of the tank. We are in New Mexico and the air is very dry so that may be why it's dry. Don't know for sure but giving it more thought and a little research that's what I come up with. I think I will also replace the fuel filter/separator. If you or anyone else knows more or has more info on these things please chime in with any thoughts.

Here's my guess. I will do carb, pump fuel out of tank, add fresh gas and ... have the same problem. Why? That's how my world rolls. :) But, you gotta try right? As my Dad always said, "if it was easy, it wouldn't be any fun."
 
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