Fuel leaking from hose

Anyone know what this hose is? It's leaking fuel all over my floor in the garage.[You must be registered and logged in to see this image.]

The fuel is not all the way to the top, but it's almost full. I've ridden it 20 miles since refuel, could I have put to much in? Also, I put a screw in it for now and will drain it every few hours.

Follow the hose, it's either vent line or the cap gutter hose, comes out of each side of tank back behind batt box.

You don't want to cap it if it's the vent hose.

Looks like it goes to the tank. Any idea why it's doing that?

I took the screw out and put a jar there instead.

I just siphoned about a gallon out of the tank. I'm still seeing some come out, so I'm waiting to see if that was just what was in the hose.

Does your GRiSO still have the Evap canister? If it's blocked, it can cause the tank to pressurise.

I'm not sure...I saw this thing... But I thought it was a fuel filter.
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There are two nipples on the back of the tank. Parts 14 in this diagram.

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They are the tank vent/breather hose that should normally be connected to the charcoal canister. And the water drain from around the filler cap.

(I have to edit this to continue. Bear with me.)

This is the Vapor recovery system.

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As you can see the hose with the one way valve in, part #7 is the tank vent hose. Your bike has had the charcoal canister, part#2, which contains #1, removed. The purpose of the charcoal canister is to absorb vented hydrocarbons from the tank and store them while the engine isn't running. When the engine is running the tiny spigots on the inlet manifolds, parts#11, allow the negative pressure in the manifolds to draw a constant, but insignificant in terms of how the engine runs, amount of air through the charcoal element which gives up the stored hydrocarbons which are drawn into the engine and burnt thus reducing pollution.

When the canister is removed that vent hose goes directly to atmosphere and consequently, if the tank is filled to the brim, the fuel when it expands when the bike is parked due to heat from the engine or simply sitting in a hot environment like a hot garage or even weak direct sunlight, will escape out of the tank, down the tube and onto the ground or wherever the hose is pointed.

The charcoal canister, if fitted, also has a vent to atmosphere which is where the air to purge the charcoal canister when the engine is running comes in and it is this, coupled with larger amounts of expanded, expelled fuel within the charcoal element which sometimes leads to bikes equipped with the system being reluctant to start when hot. The amount of fuel in the canister to purge means that initially the mixture is enrichened to the point that the engine is reluctant to run. A bit like trying to start an old vehicle with a manual choke, (If you're old enough to remember them! ) with the choke on and a hot engine!

Once the charcoal canister and vapour recovery system has been removed it is important to.

a.) make sure that the spigots on the inlet manifolds are either capped or joined together with a hose so they are closed off from the atmosphere.

And b.) make sure you aren't over zealous filling your tank in hot weather by trying to squeeze the last drop in. If you do it will just piss out of the hose. If you block the hose it will either pressurise the tank making it swell, or leak past the cap seal and trickle out of the gutter drain hose onto the ground again.

In countries where the canister isn't fitted like Oz, b. Is still relevant. My second GRiSO, the written off shitter, is particularly bad for 'Marking it's territory' after a fill up and even in warm, rather than hot, weather it will start pissing out a steady stream of pricey 98 octane underneath itself in a disconcerting and threatening manner while I nip into the servo to pay! This has the added issue of causing Karens to shriek at me and accuse me of being a danger to all and sundry! Offering to lick their necks will generally make them back off though.......

So, the answer is, don't fill to the brim unless you can ride off immediately and plan to travel far enough to use a couple of litres of fuel and don't fill up just before you go and park up, be it at home or anywhere else.

This doesn't look right. I'll have to take the battery out tomorrow and see what's going on. I didn't see a canister.[You must be registered and logged in to see this image.]

TonyL2027 wrote:

I'm not sure...I saw this thing... But I thought it was a fuel filter.

That's the non-return valve. It might be stuck open.



There's normally two fuel breather thingies on US bikes. There's a blue/orange non-return valve, plus the canister.

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TonyL2027 wrote:

This doesn't look right. I'll have to take the battery out tomorrow and see what's going on. I didn't see a canister.[You must be registered and logged in to see this image.]

Don't worry about that. It's the gearbox breather I'm pretty sure. It just goes to atmosphere, loops up and pokes to the left of the bike.

Thanks guys! I'll make sure I don't fill up to the brim! In the meantime, I'll try to find that canister and replace it with a bulkhead. Should I replace the one way valve?

Do the full canisterectomy, if not already done. I strongly recommend removing everything related to the evap recovery system. Don't plug anything, except the holes on the intake manifolds. Don't join any hoses together.

Beetle, it looks like the diagram shows the one way valve has been removed and replaced with a bulkhead. Is that true?

Not sure. It certainly looks that way, but Guzzi are quite rubbery with that kind of thing. You’d have to get someone in the US with a late model to check. Yours is definitely a valve.

The valve seems to have just been replaced with a connector. Who knows why? Perhaps they had a whole load of pre cut pipes to use up when they deleted the valve.

Wonder if I should do the same. This guy removed it on his Aprilla:

Here is the bad scenario. Those lines on both sides of tank go in and are sealed w/whatever they use.
I have replaced 1 or 2 tanks because they leaked fuel inside the tank into the hose. Then the tank will always leak.
The blue & orange tip over valve is an updated version of the all grey one that would get clogged.
I take all that off, no issues so far.

GuzziSteve wrote:

Here is the bad scenario. Those lines on both sides of tank go in and are sealed w/whatever they use.
I have replaced 1 or 2 tanks because they leaked fuel inside the tank into the hose. Then the tank will always leak.  
The blue & orange tip over valve is an updated version of the all grey one that would get clogged.
I take all that off, no issues so far.  

Thanks! I think I'm going to. Just need to find the right coupler to go in there. It looks like the PN is AP8121267 on the part list that Peter posted. AF1 racing says they'll have it in 8 weeks. Seems kind of a long lead time for a $10 part. Wonder if I can find a suitable sub in the meantime.

Browse through here.
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Ah yea... Thanks!

You can get a fitting at auto parts or hdwr store.

I replaced the one way valve with a splice. Does this look sufficient?

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Should be fine.

Thanks Peter!