Gas Cap Leak

A few months ago I purchased a new fuel cap from our favorite vendor. Removed the old crappy one and threw the new one on. For some reason, when I fill the bike up it still leaks from under the cap and down the right side of the tank. I don't fill it all the way to the top, just to the bottom of the little sleeve thing inside the opening. Anyone have an idea of how to stop this or what I did wrong putting the new one on? I tried googling/searching the forum but did see anything that comes close.

 

You'll need to do two things:

Carefully inspect the neck of the fuel tank where the seal sits for damage or corrosion, and correct as needed;

And align the cap.

Loosen the holding screw, line the hinge tab up so it's nice and straight/square, and tighten it up. Then loosen it, and "snug" it back up. Close the cap (gently) and if it needs to "draw" the holding tab a little off center one way or the other, let it. CAREFULLY open the cap and fully tighten the screw fully being careful not to disturb the position it just chose.

Repeat if necessary. The hole in the hinge bracket is larger than the screw by enough to allow quite a bit of adjustment, and every fuel tank is slightly different.

 

my gas cap did that too only because the the little box pushed on the fuel and had to force the fuel somewhere so obviously out of the tank

 

Could a missing ball valve in the gas cap vent be causing the leak?

 

http://www.xj4ever.com/gas%20cap.pdf

 

Can you show us a picture of the filler opening, and also of the inside of the cap?

dave F

 

I'll snap a picture today after I get back from the vet with the puppy and post it. I know that it isn't the ball valve, and as I mentioned before, the cap is brand new from chacol.

Fitz may be on to something since the screw won't stay tight so the cap is free to move into whatever position it needs. I'll play with it some and see what I can come up with. I kinda thought with a free range of movement, it would be ok and wasn't too worried about it moving.

EDIT:
Here's pics of the cap, hole, etc.

 

Sorry dude, I misread your original post; didn't realize you replaced the entire cap assy. What Fitz said...

 

no worries. Even though the opening looks clean/smooth, I'm gonna clean it up some more and do the adjustments.

 

It does?

I see rust, crumbly paint edges, etc.

Take the cap off; and take a Scotchbrite pad and CLEAN the flange where the cap mates so it's shiny smooth.

Then do the adjustment as I described. If the screw won't tighten up, perhaps it's too long?

 

Understood.

 

On some of my bikes, I must press down fairly hard on the front of the cap as I turn the key.....if I don't then it can leak. If I do the 'press&turn' thing, then they stay nice and dry. I'm now in the habit of doing that on all of them all the time.

Maybe something as simple as that...........maybe not.

Dave