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Gas tank breather tube help.

4.7K views 4 replies 2 participants last post by  BrockSamsonsRealDad  
#1 ·
OK, so I'm trouble shooting my 1986 VT700C. I realized the other day that the breather tube (skinny black tube in rear of tank next to the larger red one) coming from my gas tank was leaking gas. When I tipped the tank to the left so the gas level was below the tube it dried up, then when I returned the tank to level it leaked again. I emptied the tank and removed it and that breather tube was totally full of fuel. What could be causing this? Any suggestions moving forward? Thanks in advance!
 
#2 ·
This has to be a blockage of some kind unless the lower tank was full. You should be able to get to the top of the lower tank easily enough with the top tank removed to see if there's something clogging it.

That tube is just there as an air-return when you're filling the bike, to lessen any "glugging" sounds and to lessen bubbling when the tank is being filled. Once the air is out of the bottom tank it should be full, but if it's holding fuel when the bottom is empty it must be blocked or crimped in some fashion.

If it's leaking, either the top or bottom clip wasn't on or it's cracked so you'll probably need to replace it. You should be able to find a suitable length of suitable inner diameter fuel line easily (it does hold fuel so needs to be fuel line, some rubbers for air lines will swell or even dissolve in gasoline!)
 
#4 ·
I've seen that written as well but if you think about it, once you have the bottom tank full there's no air to come out and nothing to stop the tube filling with gas.

On my Cali model the gas cap is sealed and the breather is through a charcoal canister at the front of the bike. That tube should be empty as far as I know, as it's an inlet and needs some pressure to blow anything back into it (eg if the bike is parked in the sun). I believe it also goes up to near the top of the gas tank in front of the cap where there's an air space anyway.