Fuel coming out the gas cap

I filled up my Kz700's gas tank the other day to about 4/5 - there was
still some room left. I was riding for about 5 minutes when I noticed
gasoline was running down the sides of the tank and it was coming out
the cap! What could cause this?

 

Even if the cap was grossly leaking - how would it be pushed out the
top? ( a new cap is like $80...gah)

 

Some gas caps have vents. If the gas tank is overfilled, the cap would
leak gas out the vent hole.

But later models would have unvented caps. You should check to see if
your machine had an evaporative control system that used an unvented
cap.

Check the parts diagrams on www.partsfish.com to see if your machine
had a charcoal canister.

During the mid-1980's, evaporative control systems were added to many
motorcycles.

If your machine had an evaporative control system, it would have a
charcoal canister and some hoses going from the gas tank to the
canister and a hose with at least one anti-backfire check valve
connected to the carburetor. Fumes would be stored in the charcoal
canister until the engine was started and then the fumes would be
sucked into the engine when it was started.

Look on the back side of the side cover for a decal that shows how to
hook up all the evaporative control system hoses. Kawasaki color coded
the hoses with different colored tape and the decal has dots of those
colors to show where the hoses went.

 

A leaking filler cap, duh....

 

And this would cause gas to be pushed out the top of the tank?

 

Thanks for the reply.

I think the california model had a canister but my model does not. It
does have the anti-backfire check valve though.

 

If it's leaking, it's leaking..... ;-)

 

If everyone's on the same page, please accept my apologies; however:

It seems like Masospaghetti wants to know _why_ the gas is coming out of
the top of his tank, perhaps as a simple inquiry, perhaps as a means of
determining whether the gas cap is truly at fault.

If it's the second reason, I'd think that the leaking gas cap is a
problem that needs correcting irrespective of its "true" cause. If
there's another problem, the gas will overflow out of the vent hose
(it's still there, right?) instead of all over your tank. This is
preferred for several reasons. ;-)

I'd say, replace the relevant bits of the gas cap (dunno whether it was
suggested to replace the gasket only, or the entire cap) first, then see
if the problem recurs. If so, get back to us.

Let me know if I've gotten anything wrong, and happy riding.

--
Later,
John



'indiana' is a 'nolnn' and 'hoosier' is a 'solkk'. Indiana doesn't solkk.

 

Gasoline expands when warmed. The gas in the
Underground tank is at about 50 F. On a hot day it
can expand a surprising amount.
I had this happen once, touring on an old Honda with a
center mounted filler cap.
Gasoline on your scrotum fells cold at first.
Then there is a uncomfortably strong impression of heat......
Wakes you right up!
Rode FAST to the next rest stop...

MadDog

 

P.S.
Check for wasp larva in the overflow hose.
They tend to leave them there if the bike is stored out-doors.
MadDog