Fuel cap leak

[greenbarn]

Well, I was hoping to find mine loose, but not so lucky.   Good seal impression all the way the "Laborinth" so I don't think that's the leak I had on mine.  I just hope to not fill it far enough to fine out!

[Troll]

See, I told you taking that cap apart wasn't for the faint of heart...That set of passages are officially called a labyrinth. That super thin black rubber gasket is where mine was leaking. The little phillips screws were loose.....

[greenbarn]

Greenbarn,
I've got a '99 Drifter.  And my plate will reverse. You can also see indents where me, or someone else, had tightened it, after it had slipped from its mount.  Yes, they are little marvels of over-engineering!

Mine "will" reverse also -  But it won't fit right.  I meant it will only go together one way "correctly" - every piece I saw had some way to tell it was the right way or wrong way, like those locator pins.   

[Gordo]

Greenbarn,
I've got a '99 Drifter.  And my plate will reverse. You can also see indents where me, or someone else, had tightened it, after it had slipped from its mount.  Yes, they are little marvels of over-engineering!

[CDNRatMan]

  remind me never to take that apart.......

[greenbarn]

I did not devote the time to studying what possibly could be the reason for all those internal passages.  Some of them just appear to go back and forth within the tank for no reason.

[greenbarn]

Wanna know something weird?  The cap on my 1500 is completely different. Similar, but the innards are different.  I haven't seen anything so unnecessarily complicated.  My 2002 800 ad 2003 1500 appear the same inside.  What year is your 1500??

Mine has not leaked from the key hole, but just leaked gas around the fuel cap.

I did notice that (in regards to your plate on backwards) everything I saw would only go together one way - any other way would not fit properly.  I wonder what the story is on yours being put together wrong??

[Gordo]

With the plate mounted with the stamped pins down, the plate does not completely seat against the vent tower and key/lock tower.  I figured fuel was travelling between the two.  In the pic, you can clearly see that the plate is not seated.
The second pic shows proper assembly, with stamped pins up.  I put a bit of grease on the top side, and placed it into the housing.  The grease held it in place while I assembled it.  Screwed everything back together and a test ride confirms no more fuel venting through the key hole of the cap lock.
So I don't know if originally had 2 problems, the vent seal and the plate reversed, or if I reversed the plate when I took it apart several times looking for the original leaking.
I hope I've beat this beast for good!

[Gordo]

So it is finally warm today.  I filled the bike  up, not stupid overfill, just really filled.  As I rode off, fuel bubbled out the key hole when I was stopped in traffic.  Obviously a venting issue.  Back to the garage, and pulled the cap off, again.  What I found was that the plate inside the cap was upside down.  Note that the 2 indents, or locator tits are down when I pulled it apart. (Down on the bench, but actually other way up when installed.  OK?)  Also note that I have already removed a tiny cylinder that rests on the pin of the lock assembly, just above the orange rubber seal.  Don't loose that!
On the second photo you can see the 2 locator stamped pins on the plate.

[Pilgrim]

third pic looks like mine...I don't think my bike is a california model.

[Gordo]

First pic shows no gasket.
Second the gasket over the vent.
Third one shows what it all looks like together.
I've included a bunch of pics from various angles for reference as it seems quite a few have disappeared over the years.  This is Canadian bike.
Watch out for all the little "O" rings.  I put a towel in the tank to prevent a fishing trip.

Can't seem to get them rotated properly, sorry.

[greenbarn]

Oh, I saw it all right....  saw it real up close and personal, I did....

[CDNRatMan]

Sorry Big Foot but he is easily distracted, he can not even see a moose on the road.

[greenbarn]

Now solve Big Foot's issues.......

Hey, you're the one that got us off topic with a geography lesson. 

I thought we were still working on fuel cap leakage...  I don't know if his is the large main cap seal leaking?  could be - or could be loose screws inside the assembly, like Trolls.   Or evidently there is another mode of interior failure.

[CDNRatMan]

Now solve Big Foot's issues.......

[greenbarn]

Ok Moose let me educate you, if "CA" stood for Canada it would have been as CDN but the manual was an American printed book so the "CA" stands for California.

[CDNRatMan]

 

So that explains the "CA" on the drawing.....  Here I thought maybe it was for CAnada...

Ok Moose let me educate you, if "CA" stood for Canada it would have been as CDN but the manual was an American printed book so the "CA" stands for California.

[greenbarn]

So that explains the "CA" on the drawing.....  Here I thought maybe it was for CAnada...

But seriously, even so, I've thought more about this.  My screws were not loose - I checked them about a month ago, after I had fuel run down my let twice after filling up.   Maybe I was over-filling, but if so I've been over-filling the whole time I've had the bike.  I (used to) fill to about half-way up from the "baffle" at the bottom of the fill-neck, to the top of the fill neck - on the side stand, of course, so when you tip it up, the right side gets more full- undoubtedly splashed up against the fill cap.  The main cap gasket appears to be fine, so I thought perhaps gas is leaking through the innards of the cap, and out through that hole (which goes to a drain line to the ground). So, maybe if it had a rubber gasket on that nipple, it would drain to the ground, not down the side of the tank.

So I took the cap apart again tonight (I had taken it apart a month ago), and I still do not see anything wrong.  Of course, it hasn't leaked since I took it apart last month --but then again, I've been careful to only fill it to the bottom of the fill neck.

SO there must be more than just loose interior cap screws that can cause this problem - and after seeing the innards of this thing again, I can see it's very complex.  There are no less than 3 check valves, of sorts, numerous chambers and passages.  It seems WAY more complicated than it needs to be - rivaling the complexity of some modern EVAP and other  emissions systems on automobiles these days.

So having found nothing to fix on mine, I will install the CA seal, in hopes that perhaps if something inside the lid is not working  properly, maybe there's a chance any leaked fuel will still go to the drain.  In the mean time, I plan to continue to fill it lower.

[CDNRatMan]

  now I can sleep.......this must be another thing like the labels we get on items from California, it tells you the following

the following items are known in the state of California to cause cancer or to be hazardous to pregnant or and nursing females. That is why I am staying away from California.

[Troll]

Ok, ok...enough! It's a California only part, meant to seal the fuel system completely to prevent vapor loss. When my cap was leaking, I got one, and put it on. It goes under the cap hinge, inside the ring...but it didn't help a bit. The screws holding the center of the cap to the cover were loose, and the VERY THIN rubber gasket that is supposed to seal the cap was leaking. I took the cap completely apart (not for the faint of heart) and found the REAL problem!

[greenbarn]

Moose, eh?   Smart A$$.
From what I can tell, it has to go under the gas cap hinge piece, between the tank and the hinge.  Otherwise it would fall off when you open the gas cap.  A phillips screwdriver is all we'll need to install it.

If we could just get some kind forum member to snap a picture that still has this little gem installed, I guess we'd know for sure.   Sounds like a lot of them have disappeared over the years....

[CDNRatMan]

  Hey Moose check out the picture....for me and let me know....

[greenbarn]

I just ordered 4 of them from Partzilla. $4 plus shipping --  $5.85 each with the shipping split 4 ways.   I need 2, so if anyone needs one, I can either bring it to Wisconsin (assuming I get them in time) or I'll drop in the mail. 

[JagLite]

Huh?   
Well look at that!   
There is supposed to be a seal there...   
No wonder my tank seeps a tiny bit when the tank is full.   
Thanks for asking, and thanks for the answers!     

[CDNRatMan]

  now I have to get dressed and go out to the shed at o dark hundred and see if there is anything in mine.....thanks GB......