gas tank not venting properly

I have a 2002 VFR I just bought with 2800 miles and the gas tank vent is clogged. I am assuming it is throught the gas cap as I checked the lines under the tank and they are clear. Has anyone else had a problem with the gas tank not venting correctly? Mine has created such an internal vaccuum that it actually distorted the tank.

 

Bent the tank? Wow, that's some heavy suction. I was thinking the vent hose hung down and went below to drain on the ground in the event of overflow. I had my tank upside down when I changed my thermostat. It did not leak at all. You may check the hoses again.

 

The vent hose is the one running along the side of the tank. It is unhooked from the rest of the line wich runs out the bottom of the bike.



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I used an air compressor to blow throught the line you are talking about and it is clear and the port it attaches to on the tank I blew air through it and could hear air moving through it and this morning after riding it to work I opened the gas cap and it had that same rush of air in like a vaccum. That is why I wondered if it was vented through the cap and it might be clogged. The sides of the tank where it meets the back on both sides now have a ripple in them. I'll try and post pictures tonight when I get home. I might not have fully cleared the line. I'm not sure at this point. I was satisfied last night that it was good but who knows something else may have gotten back in side or it wasn't as clear as i thought

 

I appreciate the help. Thank you both for the fast replys

 

If the line is clear up to where it attaches, your blockage may be between the bottom of the tank and the vent opening. Can you blow air from the overflow hole in the top of the tank out the bottom of the line? An easy to check is place a plastic drinking straw into the overflow hole. Blow air into it and have someone hold their hand (or use you bare foot) at the bottom of the line. you should feel air coming out.

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I've had this happen once, but was lucky I had to fill up before any damage was done.
I had thought the tank pressurised as when I unlocked the cap... BANG!!! I scared everyone at the fuel station. Musta been air rushing inside then popping out... anyway.

My problem was that I lowered the tank onto the hose that morning.

 

Yep,

I had the same problem of having done some work under the tank and then having accidentaly crimped the venting hose when I lowered the tank. When I finally twigged what was going on I found the hose not sitting in the correct spot with obvious signs of being pinched. Sorted that out and no problems there after!:redface:

Cheers!

 

I had to stop three times and open the gas cap, this however did not save the tank from further damage. I used my air compressor to blow air through the vent hole with no success, its clogged and (I couldn't get good pic's of the damage) the damage is worse. The bike is a California emissions bike with the EVAP system as well. So now I have two questions 1) where do i get a new gas tank (mostly because I'm so unhappy with the new wrinkles in this one I don't want to look at it any more) and 2) how do I get rid of the entire EVAP system I live in North Carolina!!!

 

Ron Ayers or Service Honda usually have competitive prices on new parts. You could also try flea-bay. A competent paint and body shop may also be an option if you get the line unclogged.

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the bottom of my tank has two lines according to the manual one is a vent line the other is the overflow line are they connected inside the tank? Can either one be used as a vent line and the other plugged? The larger of the two lines (the overflow) is open and can pass air through the smaller is clogged can I use the the "overflow" and totally block the little tube (not that it would be too hard)

 

Mines an 04 and I'm almost positive that it only has one line. I saw what your talking about in the manual, but I've had the tank off twice and I only remember one vent line. Maybe they changed between 02 and 04. Can you run some wire up the vent line(s) and see if you can clear them?

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The larger of the two lines is wide open I can get a small screwdriver in it the smaller one nothing, I can't get a piece of safety wire through it. This has the California emissions EVAP system and both lines run to the EVAP throught a solenoid. I saw the pic you have with only one line and am hoping I can remove the EVAP system and vent through the larger tube to normal atmosphere instead of throught the EVAP system and plug off the smaller tube but if on mine the larger tube is overflow only then I'm not sure of my options.

 

correction the small line goes directly to the EVAP can and the overflow goes to the solenoid then the EVAP if my memory serves me. I'm at work again trying to figure this out, that is what works for right?

 

I now know what the has been wrong with my gas tank. My 2800 mile "deal" of a buy has been worked on by someone. The previous owner had the tank cleaned and resealed. It has the Honda RTV sealant around the gasket to the fuel pump and the sending unit. When I removed the fuel pump to get a better look at how the tank was vented the pump, and sending unit, looked like it had been on a fifty's International Harvester truck that had been parked in the Atlantic Ocean for twenty years. The inside of the tank had a beige-ish paint on it. I'm guessing this isn't factory since I also own a 954RR and am having it custom painted and it didn't have any paint/sealant inside of it and the fuel pump on it looked brand new when I pulled it.

So here is my theory the guy that sold it to me knew (insert buyer beware here) it was rusted inside paid to have it fixed and then put it up for sale. While riding it some how a piece of debris found it's way into the vent tube and the pressure in the tank eventually forced it (or multiple pieces of debris since there was no shortage inside the tank) to the point where it blocked the vent tube the fuel pump created enough vacuum inside to cause the tank to buckle at the crease where i noticed it, by this time it was too late.

Further evidence that the bike had been worked on is the foam glued to the bottom of the tank was glued to the wiring for the sending unit and when I went to disassemble it the wiring had already been torn away the foam.

I appreciate everyones help in this matter. I'm now going to say a few more expletives drink a beer and start looking for replacement parts.

If anyone can think of what else this may have affected please let me know I'm going to try and cover my bases before this thing hits the road and call the dealership this guy took the bike to and see what I can't find out from them.

Thanks again for the help

Chris