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Gas tank vent hoses, help needed! '97 M750

Started by Mike Qube, February 16, 2010, 03:15:21 PM

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Mike Qube

February 16, 2010, 03:15:21 PM
I have a '97 M750. Lately I've noticed a gas smell in the shed when I go in there. Tonight after I started it up and ran it for a bit, I lifted the tank and there was gas dribbling out of one of the vent hoses coming from the tank. There are two hoses, a smaller one that runs down by the rear brake pedal and then a larger hose that was in that same area, the larger one was the one with the gas coming out. When I lifted the take even further, gas started pouring out of it. To me, it doesn't seem that it sound be pointed at the ground if gas can pour out like that. Where does that one go?

ducpainter

#1
February 16, 2010, 03:20:50 PM
Quote from: Mike Qube on February 16, 2010, 03:15:21 PM
I have a '97 M750. Lately I've noticed a gas smell in the shed when I go in there. Tonight after I started it up and ran it for a bit, I lifted the tank and there was gas dribbling out of one of the vent hoses coming from the tank. There are two hoses, a smaller one that runs down by the rear brake pedal and then a larger hose that was in that same area, the larger one was the one with the gas coming out. When I lifted the take even further, gas started pouring out of it. To me, it doesn't seem that it sound be pointed at the ground if gas can pour out like that. Where does that one go?
There are three hoses total on a carbie tank.

One is the fuel supply.

The other two are a vent which was originally connected to the charcoal canister, and a drain.

If fuel is draining from those hoses either the fuel is warm and expanding and coming out the vent, or the cap leaks and it's coming out the drain.

Either way gas is supposed to come out if the tank thinks it should happen.
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
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Mike Qube

#2
February 16, 2010, 03:23:46 PM
The canister was removed by the previous owner. The bigger hose looks as if it should go somewhere. Was something supposed to be done with this hose when the removal was done?

ducpainter

#3
February 16, 2010, 03:26:35 PM
Quote from: Mike Qube on February 16, 2010, 03:23:46 PM
The canister was removed by the previous owner. The bigger hose looks as if it should go somewhere. Was something supposed to be done with this hose when the removal was done?
Exactly what was done...vented to the atmosphere.

If you still had the canister the bike would run like ass because the can was loaded up with fuel.

It's not really an issue...honest.

Unless of course your tank is leaking at the hinge.
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."


Mike Qube

#4
February 16, 2010, 03:28:56 PM
It doesn't seem to be leaking from the hinge. I could see it coming out of the hose when I lifted the tank up. It seems that the further the tank is lifted the more pours out.

ducpainter

#5
February 16, 2010, 03:30:04 PM
Quote from: Mike Qube on February 16, 2010, 03:28:56 PM
It doesn't seem to be leaking from the hinge. I could see it coming out of the hose when I lifted the tank up. It seems that the further the tank is lifted the more pours out.
Don't lift the tank.... :P









































;D
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."


Mike Qube

#6
February 16, 2010, 03:30:47 PM
Come to think of it, I recently filled up. Is this line some sort of overflow that comes from near the cap?

ducpainter

#7
February 16, 2010, 03:34:49 PM
Quote from: Mike Qube on February 16, 2010, 03:30:47 PM
Come to think of it, I recently filled up. Is this line some sort of overflow that comes from near the cap?
Yes....

The two hoses on the tank bottom come from the cap area. The fact you just filled the tank is evidence everything is working as planned.

I know it's winter...

try not to worry. ;)
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."


Mike Qube

#8
February 16, 2010, 03:35:50 PM
Quote from: ducpainter on February 16, 2010, 03:34:49 PM
Yes....

The two hoses on the tank bottom come from the cap area. The fact you just filled the tank is evidence everything is working as planned.

I know it's winter...

try not to worry. ;)

Everything makes sense now. Thanks for replying so quick!

koko64

#9
February 16, 2010, 03:48:39 PM
Quote from: Mike Qube on February 16, 2010, 03:30:47 PM
Come to think of it, I recently filled up. Is this line some sort of overflow that comes from near the cap?

+1 or +2 one is an overflow and one is a breather.

You may hear the breather on a hot day venting evaporated gas when the bike is sitting there with a hot engine or if the bike is sitting in the sun. The breather should vacuum into the tank with the fuel pump operating.

The overflow hose is linked to that hole on the inside of the neck of the gas tank, so a fuel overflow spill goes on the ground and not all over your gas tank and then down onto a really hot engine.

A really full tank when lifted up may drain a little fuel down the overflow hose. Mine used to but doesn't any more since the seals have swelled nicely!

It's worth making sure they are not kinked or blocked.

Cheers [drink]
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