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Gas leak - mpg down 30%


sguerrero

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Guys, a couple of days ago I've notice it was dripping gas form a little tube(hose) right next to the kickstand.
 
It was 4pm like 70F . I had a cover on. It was dripping a drop every second. I freak out ... today, the tank looks like someone is stealing gas.
 
Do you know why that is?

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If you fill the tank the fuel will be cold from the underground tanks,
due to the warm tank and outside temps it expands, this is not helped
by having a nice hot lump of a engine directly below it, normally it
would just vent vapour but if you filled it right up then only rode
a short way the fuel it's self could be vented and that's what the pipe is for.
 

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If you over fill your tank or if gas expands in your tank it will come out that overflow tube. Now ask yourself how much gas you put in your tank? Did it come up past the metal plate with the hole in it for the nozzle when you filled it? If so that may (probably is) be the problem. Good luck and let us know what you find out.

Beemer

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The dripping has stopped , since the tank is at 1/4 now. The next trip to the gas I will fill it up 3/4.
 
I'll let you know the outcome
 

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Well, if your gas mileage has really dropped 30% as it states in the title, I'm thinking this is not because you overfilled the tank. There's no reason for the fuel to syphon out until the tank only has 1/4 level left.
 
Have you ever noticed any air movement sounds when you open the fuel filler - does it pop open or do you have to lift on it when the cap is unlocked?
 
You might have a leak at the fuel pump plate - I've not paid much attention to stuff under the tank, but it might be worth a look if it continues to leak when there's a 'full" tank.
 
If it continues to drip, take the faux tank covers off and poke in there with a rolled up paper towel to see if you can find an origin for the drips.

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Wow! It kept leaking all the way down to 1/4 tank from a fill-up?! I didn't expect that. It dripped way more than it should've for just gas expanding or being overfilled. That's a serious leak so be careful. Been a few days now so what's the word on it?

Beemer

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Wow! it kept leaking down to 1/4 tank?! I didn't expect that. It dripped way more than it should've for just gas expanding or being overfilled. That's a serious leak so be careful.
Gas everywhere!
ghost_rider_by_nachomolina-d32ew9j.jpg
 
It could very well be a leak from the fuel line connections. Once the gas is at 1/4 tank there's not enough head pressure to keep leaking.
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cndnmax
 
"It could very well be a leak from the fuel line connections. Once the gas is at 1/4 tank there's not enough head pressure to keep leaking."
 
That's what I was thinking. BTW, Nice pic! lol! I knew Cage was dumb but riding with a gas leak?!!!
 
 
 

Beemer

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Once was a time that BMWs, Triumphs and Aprilias came with a plastic quick-disconnect in the return fuel hoses. They were notorious for breaking and then allowing gasoline to spray all over a hot motor. My Futura's fitting had a 90 degree elbow that failed enough that Aprilia was forced into a US (only) safety recall. And only the elbow half at the TB was replaced. Many of us opted for metal in both halves long before the official NHTSA recall. I still hav my recall notice - never acted on as min is now even safer. Sadly, there were quite a few toasted Futuras in Europe - likely due to a failed hose fitting. Those guys never knew the danger.

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Well, apparently the problem stopped without any of my intervention.
 
I did check all the fueling connections, hoses and everything seems OK. I went to the mechanic, he said "Nothing is wrong". One key value to identify leaks is MPG.
 
Conclusion. It could be an issue with the device inside the tank that measures how many fuel there is left. Since it will require a couple of days to open and close the bike. I decided to pay close attention when I was noticing the most fuel reduction and work from there.
 
 

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been my experience, especially with such a small tank, that the best way to keep tabs on fuel used is to see how much can be added to the tank after X number of miles. The gauge is there just to help you not run out of gas somewhere
 
So, it's stopped dripping?

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been my experience, especially with such a small tank, that the best way to keep tabs on fuel used is to see how much can be added to the tank after X number of miles. The gauge is there just to help you not run out of gas somewhere 
So, it's stopped dripping?
 
Yeah the other day my average MPG reading was 2mpg. So I'm not putting much trust on the accuracy of those readings lol.
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  • 2 weeks later...

Actually the dripping continues. The trigger is direct sunlight hitting the tank. Around 3-4sh is when the sun it is at its wormest were I park the bike. The tank at 50% full and still is dripping through the hose right next to the kickstand. 9930e14af7b95c02686ab6aa69728be6.jpg

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Well I did pull the plastic covers to make sure the hoses were fitted correctly. There is no leakages from other places than this hose. So I'm assuming everything is OK.
 
 

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  • Global Moderator

This seems rather odd....
that hose is connected to the filler neck to prevent overflow from going inside the plastics and ruining them
 
There shouldnt be any fuel coming out unless you've freshly filled up
Even then there shouldnt be much coming out
 
Id recommend taking it back to the mech if you can
If you're under warranty tell em you want a new tank because it has a care porosity issue
 

ATGATT... ATTATT, two acronyms I live by.
 

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Park it in the shade and see if it does it then.
 
 
I've had bikes do this with the sun beating down on the fuel tank - just a couple of drops over the course of the whole afternoon.

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