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Fuel keeps dripping from drain hose

12K views 48 replies 16 participants last post by  Agolini 
#1 ·
Mi issue is that the drain hose that comes from under the tank forward of fuel pump keeps dripping gas. At first I tough it was the carbon canister. I removed the carbon canister capped the vacuum hose from the throttle body and routed the other hose back down the bottom for drain. The canister was full of gas. Now the hose keeps dripping gas like a drop every minute. I ran the bike to see if it would make a difference and still dripping. My bike is garage kept and now my garage always smell like gasoline and of course the wife keeps complaining about it. It is dangerous since I live in vegas and my garage gets very hot and to add gas fumes to it could be a recipe for disaster. Any idea what could be wrong? This is on a 16' TVL. Thanks in advance.
 
#3 ·
Make sure the correct hose is connected. I don't know the TV but in my F3 the left on tank is the overflow and the right is the evap line. If they are mixed up you get funny things happening. Like hard starts and on hot days with high tank fuel levels you get fuel that should be captured by canister just going to bottom of bike. Basically the left hose goes to right and vice versa and is easily confused.

The other possibility is that the fuel tank is bad now internally. These lines travel inside the tank up to the fuel filler/ cap. If they are leaking or broken in the tank you will have fuel entering the lines when they should not be.

Check for proper hose connections and the those lines are not leaking inside of tank. I think with a 2016 bike it is under warranty. You use ethanol free fuel?
 
#4 ·
I did not disconnected any hoses from the tank. Just the 2 hoses that connect to the carbon canister. For some reason the smell is very strong. Is not like there a big puddle under the bike. I do have a soaker pad under the bike to prevent spreading.
 
#6 ·
Did this and indeed there are bubbles coming from inside the tank. Taking to the dealer tomorrow. Called them and they told me it was normal this time of the year. I told them this did not happen last summer. Thanks for the advice.
 
#8 ·
Well, took the bike to the dealer today and they are ordering a new tank and carbon canister. Now comes the waiting time for parts. Love the bike, but have own the bike less than a year and have more trips to the dealer due to issues that all the bikes I ever had together. I had a lot of bikes, lost count after 15. I guess is time to start looking at other options.
 
#9 ·
My garage has smelled of fuel badly since I brought the bike home recently from having a new tank put on. I drop the bike off today to have them assess. I will have them check this fuel line. I assumed they didn't put one of the fuel lines on correctly when they put the new tank on, but if there is a ruptured line, that could explain the smell.

My bike isn't leaking fuel, but the smell is definitely there.
 
#10 ·
If the bike has seen ethanol fuel at some point it can cause swelling. Then when you go to non-ethanol things shrink. This can cause fuel injector leaks and leaks all along the way.

If this has happened and you can stick with non-ethanol you can try to drain tank completely and allow the tank and lines to shrink back and tighten. I think it takes a while to have the original shape come back.

I've heard of people having to use ethanol just to keep the leaks away even though they shouldn't use ethanol.
 
#11 · (Edited)
Sorry to bring this up again...

Hi,

Not totally new here, had an account since last year when I bought a Brutale 910R Hydrogen.
Sold it, and now own a Rivale 800 2014.

Here's the problem: leaking fuel from the hose under the bike.
--> The one (there are two) going to the tank, the other one goes to the front (Coolant).
Anyway, the leaking hose is connected via a Y-connector to the underside of the tank. Under the tank are, at least with mine.... two drain plugs (steel) that are internally connected to (different ways) to the filler/ opening. The leaking hose is connected (Y piece) to both.
According to what I read... that could be strange of be a modification and the Canister is gone?
Looking at https://shop.startwintrading.com/en...le-800/rivale-800/carbon-canister-assembly-16
I don't have part nr 1.

I've got everything apart. Anyone with a good follow up what to do?

Other question: WTF is that filter like thing at the underside of the fuel pump (inside the tank).

Thanks everybody!

Groeten,
Daniel
 
#12 ·
The filter thing under the pump itself is a strainer at the pump pick-up. The fuel filter itself is downstream of the pump.

The hoses are connected to the gas cap water drain (in the cap area) and the gas cap atmospheric vent. If fuel is coming from the drain hose from the tank one of several things is happening:
You have overfilled the tank and it is draining from the cap area water drain
Your cap vent system is compromised and fuel is escaping through the cap vent
The hoses are damaged or deteriorated inside the tank between the cap area connection and the fuel pump base connection.
 
#13 ·
Thanks a lot. Great and complete answer.
Guessed same thing with that filter. Strange thing, never saw it (It's probably me :) )

I thought I overfilled, cause the tank is not that big... hihiii
But, it was still coming out of the hose. Even after filling up again (and less, 8 liters?)

I cleaned everything now, especially the vent system.

I don't get that last one. There are no hoses inside the tank going from the tank vent (at the filler cap) and the pump?
 
#14 · (Edited)
The gas tank must have a water drain for the gas cap recess and a passageway for fuel vapors and air to escape and enter the tank (venting). The vent is through the gas cap.

On models with a carbon canister (evaporative emissions) this vent leads into the canister. You say the canister has been removed so this vent is to open atmosphere.

On old bikes the vent was at the cap itself, but no modern bike (other than off-road) do that. The risk of fuel spill from the cap vent has led to venting out below the chassis via hoses from the bottom of the tank (where yours is leaking)

There must be tubes from the gas cap area to accommodate these needs. On some metal tanks these are welded in pipes (which have been known to crack, leaking gas and causing occasional recalls from every Japanese manufacturer).

Your MV has rubber hoses. They lead from the cap to the spigots in the bottom of the tank.
Here's a snip from the workshop manual showing them.
 

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#15 ·
So, if I understand correctly, the hoses are correct. Only the canister has been removed. And the previous owner did a by-pass.
Then why does it drip?

What I did today was clean the lines inside the tank, did it with air. Alle clear.
And I did some testing with water to see what happens when I put pressure on the lines inside the tank and close the line at the end. To see if I see or hear any bubbles or air leaking. Non so far!
I have to say that you can't get water everywhere off course, just at the bottom part of the tank.

Thanks a lot for thinking here with me esq'z me !!
 
#17 ·
@danfoksan: Your removed canister was EXTERNAL to the tank; therefore, there can be no effect to the hoses inside the tank. If there is fuel leaking from the hose downstream of the "Y", then one of the hoses inside of the tank is leaking. That leak can be through-wall, or it can be at one of the connections.
What he said. Forget the evap can. You have one of the 2 hoses inside the tank leaking. Period. Take the pump out and inspect the hoses.
 
#16 ·
@danfoksan: Your removed canister was EXTERNAL to the tank; therefore, there can be no effect to the hoses inside the tank. If there is fuel leaking from the hose downstream of the "Y", then one of the hoses inside of the tank is leaking. That leak can be through-wall, or it can be at one of the connections.
 
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#18 ·
Ok. Clear.

I had the pump out, and did a visual check on the lines. But (fock, what is the word for the material) the internal lines are packed (made of the same material as the tank). You can do a visual check and feel with your hands. That's it.
What I did is partly fill the tank and put pressure on the both lines, and block te exit. Searching for a cracked wall. But nothing.

Excuse me for misunderstanding or putting it in the wrong words.Just for sure... does any of you have the rubber lines on the inside of the tank?
 
#19 · (Edited)
My MVs both do, but I don't have a 3 cylinder newer model.

You can use a Miti-Vac type tool to vacuum test or pressure test the lines inside the tank. You would need to remove the gas cap and block the holes there, then attach the vacuum/pressure pump to the hose connections on the bottom of the tank.

Should hold a few mm/hg vacuum and a few psi of pressure. If not, there is a hole in the pipe. Or just attach a piece of tubing and use you mouth to blow/suck air. Like putting your finger over the end of a straw.

Did not think MV was using formed in pipes on a plastic tank. Kind of difficult molding exercise. Rubber hoses would be simpler....but I don't know.

The Workshop Manual diagram clearly shows hoses, but the parts catalog does not !!!

I would certainly contact MV and/or your dealer and tell them. Leaking gasoline is a safety hazard. If the molded in pipes are compromised the manufacturer would probably want to know.
 
#21 ·
Tried testing yesterday with a full tank.

What happens is, that fuel comes dripping out the ' water drain ' . And it comes from the gas cap.
From what I could see is that the fuel expands or moves around and escapes or via the rubber lock (but it seems to close good) or via the passageway for fuel venting.

I cleaned and dried everything after leaking, en was sure there was no fuel at the gas cap or so ever. And there was no smell or leaking at all.

So.. the story continues and has to do something with the passageway. Can I shut it of or something? Or remove the rubber at the gas lock?
 
#22 · (Edited)
OK.....there is a small rubber seal from the gas cap vent into the fuel tank passage. If that seal is missing then any gas getting through the vent will spill into the cap area and go down the water drain. See attached snip from workshop manual.

I suspect that seal is missing.

And another note...never fill your tank up into the fill tube under the cap. It should be just up to the bottom of the fill tube, but no higher. On the side stand !!. Fuel expands from heat, so if you overfill and then park in the sun you will get fuel from the cap vent. This will contaminate the canister (which you no longer have) and cause running problems.
 

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#28 · (Edited)
Yeah it seems I have this same issue as well except mine is regardless of fuel level and it only leaks after the engine has been running. I tested running the bike with the fuel cap open with no leak. Would love to know the solution. I already took my bike to the dealer and they ordered a new fuel cap. It seems that my carbon canister was already removed prior to my purchase. When I blow into the vent tube with a straw there, it is not flowing freely nor do I feel air coming out of one of the tubes in front of the rear brake master cylinder.
 
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