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I have a 2004 ST3 and I have a strange thing happening. There is gas seeping out around the tank cap assembly onto the tank itself. I first noticed this when I filled up my tank until the fuel just touched the bottom of the tank opening as I rode to my next destination I noticed that fuel was leaking out around the outer edge of the cap assembly as well as the overflow tube. I had filled my tank to this level multiple times before without this happening. I did have it worked on and the mechanic said that he had rerouted the overflow tube in a better fashion. Thinking that he might had changed something to cause this condition I called him and he insisted that what he did had nothing to do with the leaking. So I started putting less fuel in at fill up. This solved the problem, but reduced my ST3's range somewhat. Yesterday, I had to raise the tank to work under it with the tank 3/4 filled and I noticed that gas was seeping out around the cap assembly again.

Does anyone have any ideas as to why this is happening? I checked the parts manual and didn't see any replaceable gaskets. Do I have to replace the whole unit to fix this?
 

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Are you securing the gas cap? After you lock the gas cap and remove the key, press down on the cap with your thumb until you hear and feel it "click".
 

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Hello Bill, wouldn't it be great if that is all that it is. I checked it out and it's hard to get it to "click" into place. I'll test it and let you know if that's it.
 

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The filler assembly screws directly to the tank and there's no gasket at all, there's only two places the fuel can come from then.
1. The rubber seal at the filler neck
2. The breather nubbin thing (vent) that sits at the rear of the filler assembly under the hinge.
#2 is the likely offender as you say the filler takes some effort to close and "click" so it should seal properly. you can check with some grease around the lip which couldn't hurt.
So that vent has a hose connected inside the tank that connects to the fuel pump assembly base, if it has a crack or split fuel will fill that hose and when you lift the tank or fill it it will leak out the top onto your tank.

To fix it you need to remove the tank, turn it upside down and remove the fuel pump assembly, replace the hose between the vent and the base and reassemble making sure you check the O ring carefully (i'd replace it) lube it with rubber grease and torque it correctly.
Make sure you use fuel submersible hose.
 

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There is one other place the fuel can get out, the o ring around the keey barrel just finished replacing mine 1 hour ago and filled the tank no leak now.
Interesting, i've never seen that before, did it leak much? It sounds like really bad luck, must have leaked into the mechanism by the grub screw on the side?

OP's description of leaking out the cap assembly makes it sound to me like it's coming out all around the gap between the fuel cap and the outer ring.
 

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Interesting, i've never seen that before, did it leak much? It sounds like really bad luck, must have leaked into the mechanism by the grub screw on the side?

OP's description of leaking out the cap assembly makes it sound to me like it's coming out all around the gap between the fuel cap and the outer ring.
Yes there was a decent amount of fuel came out. Enough to run down the sides of the tank and give the appearance hat it could be coming from the flange.
 
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