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Discussion Starter · #1 ·
Strange thing happened today after 100Km ride with one third of fuel left in the tank at the end.

After coming home I opened the tank lead to refuel it, and a strong pop got out of the tank. The pressure was not to be ignored, as it was way more than one would expect. It took me by surprise.

Any idea as to where the built up pressure came from?

I would expect there would be some sort of valve or even the overflow hose that would regulate this?

Thoughts ??
 

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The bike was going great (as usual), it wasn't vacuum as I felt the pressure being released out of the tank.
The tank should be vented in either case and I would 1st make sure that the vent is clear. Your bike was sitting if I remember correctly. That means insects could have clogged up the vent in some way. Check vent then get back to us.

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Carb or FI. There is a line running off the bottom of the tank. It typically ends back by the swing arm. As Guy stated that can become pinched or plugged. I'd check that first then the tank side. You'll have to lift the tank to check it there. I'd use compressed air at a low pressure say 20 psi. With the cap open. If it's clear you'll feel the air escaping up around the cap area.
 

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Discussion Starter · #6 ·
The tank should be vented in either case and I would 1st make sure that the vent is clear. Your bike was sitting if I remember correctly. That means insects could have clogged up the vent in some way. Check vent then get back to us.

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My bike's been ridden daily as its summer here in Australia .. by vent you probably mean the overflow hose, right?
 

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Discussion Starter · #7 ·
Carb or FI. There is a line running off the bottom of the tank. It typically ends back by the swing arm. As Guy stated that can become pinched or plugged. I'd check that first then the tank side. You'll have to lift the tank to check it there. I'd use compressed air at a low pressure say 20 psi. With the cap open. If it's clear you'll feel the air escaping up around the cap area.

Mine is 2006 Fi
I'm expecting to get a phone charger tomorrow, so when wiring it I'll lift the tank and see what's going on down there ..!

:oops:
 

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FI's have a seperate line as well. There are 2 lines one is the overflow the other is for the tank vent. The tank vent is the smaller of the 2 pipes.
 

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Overflow is a large hose with a thinner sidewall. The vent on a FI is smaller around a 1/8" and comes out the bottom of the tank. It travels down to a "T" fitting and the hose that T's off goes to nothing. That is on purpose as this prevents it from getting fluid locked if the vent gets gas going down it. I learned all this in about a 90 minute search on Google three years or so ago when I tore the bike down and was putting it back together and couldn't find anything that hose went to! Drove me nuts as I was supposed to go on a three week trip the next day.

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I'm still suspecting my carbie is having this problem causing it to I guess starve of fuel n shut down. I've blowin into the overflow line that's between the swing arm. Can hear air coming out top of tank when doing it. Maybe my breather line is clogged.. yours might be also. Mine acts up after a full tank of fuel and seems to subside as fuel level goes down.
 

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Discussion Starter · #13 ·
Ok, guys, the OP here, I have solved the problem.


The hose that runs from the fuel tank connected here:

Automotive fuel system Automotive tire Motor vehicle Hood Automotive exterior



... runs here:

Automotive tire Motor vehicle Steering part Automotive fuel system Rim



.. and ends up at this T section with 2 other hoses where the red arrow is:

Automotive tire Motor vehicle Automotive exterior Automotive fuel system Gas


Well, I took out the hose, and tried to blow thru, to no avail ..

So I used my little tyre compressor, and a small cloud of dust (or God knows what) went out. Puuffff ..

The hose is now clean.

Put it back on and no more air pressure would form in the tank anymore.


* The End *
 

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Great

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