Gas Leak / hose underneath tank

[easy rider]

I need some advice.

My bike has been fine as i was low on fuel and will have been on the lower tank with no issues.
Today filled up my tank into the upper tank for a full tank of petrol and straight away fuel is streaming from the rubber hose under my bike which has never happened.

it is not the rubber hose that acts as an overflow for water and fuel thats around the inside of the tank cap when you open it.
its coming from the hose which i think leads to the upper tank i am assuming a vent hose.

I have plugged the hose for now.

any ideas.

Thanks

 

[SupraSabre]

A picture of which hose? there are several!

 

[easy rider]

Hi
underneath the middle of the bike there are two hoses, one that leads into the top of the fuel cap to drain any water etc.
its the other tube underneath the bike that leads into the upper tank please see photo i have had to plug it for now to stop the fuel draining out.

Thanks

 

[easy rider]

Does anybody know where this rubber hose goes.

I was on two bars of petrol yesterday and there was no leaking its only since filling the tank today it is a steady flow trickling out but after a while enough probably to empty the tank by half over night.

Going to have it looked at tomorrow hope it's not going to be a nightmare to fix.

Does anybody have any ideas as to why it would do this.

 

[easy rider]

I can confirm that the hose it is leaking from is in fact the air vent line as shown in the picture provided by suprasabre
question is why is fuel leaking from here.

 

[ST-Traveler]

That is your fuel tank over flow hose you have pictured. If you overfill your tank the over flow will drain through that hose. Did you over fill your tank?

The fuel tank air vent hose in Supra's picture is from the bottom of the upper tank to the top of the lower tank, not out the bottom of the bike.

 

[easy rider]

That is your fuel tank over flow hose you have pictured. If you overfill your tank the over flow will drain through that hose. Did you over fill your tank?

The fuel tank air vent hose in Supra's picture is from the bottom of the upper tank to the top of the lower tank, not out the bottom of the bike.

I have lost 2 litres of fuel up to now from the hose under the bike so not sure what’s going on and it’s not the hose that leads to where the fuel filler cap is it’s the other one it was fine until I filled up today the tank gauge is also starting to lower.

 

[ST-Traveler]

If fuel is leaking from the (vent) hose under the bike then then some how the end of the hose to the tank has become un-hooked allowing fuel to drain. Check the connection under the tank.
The vent hose from the top of the lower tank does not route under the bike - it goes to the upper tank.

You will need to remove the upper tank to inspect what is going on. Drain the upper tank first.
I hope this helps.

 

[ST-Traveler]

The third hose under the bike is from the evap canister and is an air suction hose- So no fuel should be leaking from that one.

 

[SMSW]

If you are going to remove the fuel tank (upper), you will need a stout pair of pliers to undo the spring clips. Honda sells them compressed with a metal clip over the ends holding the clamp in the enlarged position. No need to buy new hose clamps, but be careful, the spring action is very strong. Inspect the large hose carefully for cracks. You do NOT want this hose to fail when the tank is full. Btw, these hoses are guaranteed by Honda to not fail when the tank is empty.

 

[easy rider]

If fuel is leaking from the (vent) hose under the bike then then some how the end of the hose to the tank has become un-hooked allowing fuel to drain. Check the connection under the tank.
The vent hose from the top of the lower tank does not route under the bike - it goes to the upper tank.

You will need to remove the upper tank to inspect what is going on. Drain the upper tank first.
I hope this helps.

Fuel has stopped leaking at half a tank
So if it’s filled over half then petrol leaks from the vent hose underneath the bike
It’s going to a garage in the morning
Nightmare not had much luck with the bike this year it’s been one thing after another.

 

[jfheath]

I winder if the three hoses at the rear of the underside of the main tank have been connected to the wrong outlets ? Or, the water drain tube Is a metal pipe through the inside of the tank. It may have rusted through and is allowing fuel to leak out.

 

[easy rider]

I winder if the three hoses at the rear of the underside of the main tank have been connected to the wrong outlets ? Or, the water drain tube Is a metal pipe through the inside of the tank. It may have rusted through and is allowing fuel to leak out.

Not sure but that rubber hose must go to the upper tank and if you fill up over half a tank it leaks until it’s back down to that level.
The other hose is the one that leads to the fuel cap which drains away rain water that gets into that area or if you fill fuel over the neck of the tank.

I’m confused hope the garage can sort it but for now don’t fill up fuel over half a tank

thanks for your responses I appreciate it

 

[Bmacleod]

Or, the water drain tube Is a metal pipe through the inside of the tank. It may have rusted through and is allowing fuel to leak out.

This is what I wondered when I first read this... very plausible

 

[SMSW]

I’m confused hope the garage can sort it but for now don’t fill up fuel over half a tank

I hope you have vetted this garage and have confidence in their abilities.

Or, the water drain tube Is a metal pipe through the inside of the tank. It may have rusted through and is allowing fuel to leak out.

Time to break out the proctoscope - the fiber optic model - to look around inside the tank. In addition to cheap ones on Amazon, iirc, Milwaukee Electric Tool made one for tradesmen that was comparatively inexpensive when it first came out.

 

[jfheath]

I can't find anything about the air vent pipe. I did note that the breather hose and the drain hose were drawn inconsistently on two diagrams in the manual, but they are labelled correctly. Not that it matters, because both hoses end up at the same place.

I am guessing that the breather tube into the tank is a metal pipe that behaves like a snorkel - an open end in the fuel tank above the highest point of the fluid. @easy rider was adamant that it was this tube that was leaking fluid - but I am not sure how he knows it is this one. In any case if either of these two tubes if perforated where it is inside the tank, it would allow fuel to flow into the pipe and out at the bottom end. The drainage pipe is the most likely candidate, because that it the one that gets water running down it, along with road muck which can clog up inside and create ideal rusting conditions. But if the tank ahs been sitting nearly empty for a long time .... ? Who knows.

Which reminds me - a year or so ago, I made a mental note to pour some oil down this tube every now and then just to give a bit of protection from rust forming.

With nowt better to do, and a nice new quiet PC to play with, I did a bit of graphic manipulation and colouring in. I might as well post them here.



Both diagrams are correctly labelled, but the blue and green tubes have been drawn in different positions in the second diagram. On my bike, the water drain tube under the filler cap is the wider tube, black and has a straight through joint near the seat tube. I used a green crayon for this. The fuel breather is a grey tube, slightly smaller in diameter and is joined with plastic elbow angle coupling near the seat tube. I've coloured it in with a blue crayon.

But whatever happens in the tube, I reckon that the problem is undoubtedly in the fuel tank.

I daresay that you could get away with plugging the drain hose in some way. It would have to be something more substantial than the existing rubber hose - but it would be necessary to plug the top end too, otherwise water would get into the tank. Then you have the problem of what to do when you want to fill up and there is water under the tank lid, because it cannot drain away.

If it requires a new tank, ebay may have some available. Beware you don't buy one with the same problem. Also pre 2008 model have a different size joining hose, but I believe the rest of the tank is the same for all models, but I don't know that for sure.

 

[easy rider]

I can't find anything about the air vent pipe. I did note that the breather hose and the drain hose were drawn inconsistently on two diagrams in the manual, but they are labelled correctly. Not that it matters, because both hoses end up at the same place.

I am guessing that the breather tube into the tank is a metal pipe that behaves like a snorkel - an open end in the fuel tank above the highest point of the fluid. @easy rider was adamant that it was this tube that was leaking fluid - but I am not sure how he knows it is this one. In any case if either of these two tubes if perforated where it is inside the tank, it would allow fuel to flow into the pipe and out at the bottom end. The drainage pipe is the most likely candidate, because that it the one that gets water running down it, along with road muck which can clog up inside and create ideal rusting conditions. But if the tank ahs been sitting nearly empty for a long time .... ? Who knows.

Which reminds me - a year or so ago, I made a mental note to pour some oil down this tube every now and then just to give a bit of protection from rust forming.

With nowt better to do, and a nice new quiet PC to play with, I did a bit of graphic manipulation and colouring in. I might as well post them here.



Both diagrams are correctly labelled, but the blue and green tubes have been drawn in different positions in the second diagram. On my bike, the water drain tube under the filler cap is the wider tube, black and has a straight through joint near the seat tube. I used a green crayon for this. The fuel breather is a grey tube, slightly smaller in diameter and is joined with plastic elbow angle coupling near the seat tube. I've coloured it in with a blue crayon.

But whatever happens in the tube, I reckon that the problem is undoubtedly in the fuel tank.

I daresay that you could get away with plugging the drain hose in some way. It would have to be something more substantial than the existing rubber hose - but it would be necessary to plug the top end too, otherwise water would get into the tank. Then you have the problem of what to do when you want to fill up and there is water under the tank lid, because it cannot drain away.

If it requires a new tank, ebay may have some available. Beware you don't buy one with the same problem. Also pre 2008 model have a different size joining hose, but I believe the rest of the tank is the same for all models, but I don't know that for sure.
[/

 

[easy rider]

I can't find anything about the air vent pipe. I did note that the breather hose and the drain hose were drawn inconsistently on two diagrams in the manual, but they are labelled correctly. Not that it matters, because both hoses end up at the same place.

I am guessing that the breather tube into the tank is a metal pipe that behaves like a snorkel - an open end in the fuel tank above the highest point of the fluid. @easy rider was adamant that it was this tube that was leaking fluid - but I am not sure how he knows it is this one. In any case if either of these two tubes if perforated where it is inside the tank, it would allow fuel to flow into the pipe and out at the bottom end. The drainage pipe is the most likely candidate, because that it the one that gets water running down it, along with road muck which can clog up inside and create ideal rusting conditions. But if the tank ahs been sitting nearly empty for a long time .... ? Who knows.

Which reminds me - a year or so ago, I made a mental note to pour some oil down this tube every now and then just to give a bit of protection from rust forming.

With nowt better to do, and a nice new quiet PC to play with, I did a bit of graphic manipulation and colouring in. I might as well post them here.



Both diagrams are correctly labelled, but the blue and green tubes have been drawn in different positions in the second diagram. On my bike, the water drain tube under the filler cap is the wider tube, black and has a straight through joint near the seat tube. I used a green crayon for this. The fuel breather is a grey tube, slightly smaller in diameter and is joined with plastic elbow angle coupling near the seat tube. I've coloured it in with a blue crayon.

But whatever happens in the tube, I reckon that the problem is undoubtedly in the fuel tank.

I daresay that you could get away with plugging the drain hose in some way. It would have to be something more substantial than the existing rubber hose - but it would be necessary to plug the top end too, otherwise water would get into the tank. Then you have the problem of what to do when you want to fill up and there is water under the tank lid, because it cannot drain away.

If it requires a new tank, ebay may have some available. Beware you don't buy one with the same problem. Also pre 2008 model have a different size joining hose, but I believe the rest of the tank is the same for all models, but I don't know that for sure.

It looks like the engineer I have left it with today had come to the conclusion it’s a metal pipe running inside the upper tank corroded and leaking so plug it for now and the maybe new tank
You're completely on the money very detailed response and correct.
My bike was collected by a local motorcycle garage this morning who is still operating as all the Honda dealerships are still closed due to the virus and they have found the problem.
The overflow pipe not the vent pipe due to my confusion is the problem as stated above the part that runs inside the tank is metal and has rusted through so when i fill up it leaks straight out of the tank and down the hose and then stops leaking when the tank is half full.
So the two hoses must meet up in the tank and share the same metal tube at some point to drain fuel from the top of the tank and the filler cap which i did not understand.
A new tank will be needed, but for now they have fixed drain pipe so it does not leak just need to make sure i don't overfill the tank as the drain is now closed off though to be fair i have never overfilled.
Basically my overflow pipe had been blocked for some time and i cleared it out with air last week which of course then highlighted this issue that i was unaware of in the tank as when i cleared the pipe out my tank was below half full.

Thank you for your help really appreciate it i will have my bike back in the morning they are dropping it off at work for me.

My St1300 has been a fantastic bike but this year its really started to show its age with all the gremlins.

I have sneaky suspicion my water pump will want doing at some point but i am holding off for now as its only a slight weep of oil from the hose at the front as mine is an A8 which has the hose added to the water pump.

This bike has had up to now since before Christmas new battery, coolant leaks sorted, Fi light mapping sensor which was vacuum leak, IAT sensor replaced, ambient sensor replaced,Five way T joint 3 way joint and hoses.
headlight aim motor replaced due to it going off on its own randomly on switching the bike on.
Full set of brake pads new tyres and now it needs a new tank.

She's costing me more money than when the wife goes shopping.

Though its about twelve years old now so its to be expected as it does get hammered all year round.

Thanks looks like we are back on the road again.

 

[jfheath]

Glad you are mobile again.

I dont think the pipes meet up, i think there are two separate pipes.

How did the dealer seal the pipe, do you know ?

The overflow pipe starts at the hole at the filler cap, runs through the top tank and comes out at the bootom of the top tank at the rear. The green coloured hose in the diagram above is attached to it. It now has a hole in it, halfway down its length. Any fuel above the hole will leak out. When the fuel has emptied itself onto the floor, the level is below the hole, so no more will leak out.

But you now gave a pipe in the tank which has a hole in it. Fuel and vapour can get out through the hole. Air and water can get in to the tank through the same hole. The top of the drain hole is not sealed when the filler cap is closed.

When it rains or when you wash the bike, water will get past the circular gap around the filler cap. That isn't a fault, that is what happens, and that is what the drain hole is for.

The water now has nowhere to go - except down the pipe and into the same rusted hole through which your fuel is leaking. You will get water in your tank, and petrol fumes venting upwards to the drainage hole.

So I think it would make sense to find a way of plugging the overflow hole at the top end. Bathroom sealant springs to mind, but I dont know how it would cope with petrol fumes. There is a similar 'instant gasket' that does the same job, but is resistant to oils and fuels.

Or a rubber bung.

And then you need to stop that space around the filler neck from filling with water. If it gets full, (as it will after a downpour) and you open the filler cap, some water will get into the tank, because the top of the filler neck is lower than the top of the space around the neck. A tank bag or map case may be enough. Cling film ? If you have a baglux 'bra' on the tank, it would be easy to slip a plastic sheet over the cap and under the cover.

Tape is an obvious answer, but some tapes are reluctant to come unstuck. Whatever. It isnt going to look pretty, but until you can get a replacement tank you need a way to prevent getting water into your tank.

 

[jfheath]

Which dealer do you use ?