fuel in tank boiling/gurgling

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Jan 13, 2011
Corrales, NM / Las Vegas, NV
Hi everyone, I've done a search and could not find anything so thought I'd ask. We took an offroad trip this weekend and when we arrived back to camp I could hear the fuel gurgling in the gas tank. We were out all day Saturday and the last 2 hours were crawling through a wash that was slow going. Outside temp was in the mid 70s. Altitude was about 5500 ft. Could a faulty vapor purge canister cause this? I own a 79 with a stock drivetrain and 2f engine. The truck ran great all weekend. No running issues at all.
Fuel Bubbling

I have a 82 FJ40 and are experiencing the same problem. After a long drive (hour +) there appears to be a bubbling sound in my gas tank. I recently had a new 2F motor put in and Desmogged. I searched around everywhere and could not find any info on this. Could this be an issue with the Gas Canister being hooked up incorrectly? That is the only thing I can think of. Mine appears to be hooked up right best I can tell.
I dont care so much about the bubbling as long as its not dangerous.
To the Top.
Anyone? Buluer? :grinpimp:

I realize this may not pose much of an actual technical problem with the vehicle but I really dont want to endanger myself, or others, with a possible fuel explosion. :whoops:
Chaumpa :banana:
After running the engine when you hear the "bubbling", what happens if you open the gas tank fill cap - is there vacuum or blowing?
My gas tank would pressure up or go on vacuum (not sure which) when I went to the gas station to fill up, so I blew compressed air into each of the separator lines to the gas tank to clear the lines.
I think the problem went away - not sure cause I haven't driven it much since.
The charcoal cannister doesn't exist on some non-USA spec '40s.
I think you can disconnect the gas tank line to the cannister to see if it's the culprit.
Let us know pls.
try looking up vented gas caps. i am not to familiar with desmog but the fumes need to go somewhere. either back to the charcoal canister or out the gas cap. hope that helps.:cheers:
Thanks for the responses.
Why I didnt think about opening up the gas tank cap is beyound me. !?! I will try that next time it happens and see what the result is.
Either way. I have a recently desmoged 2F and the canister is still hooked up.

I do notice that I typically have pressure build up in the tank when I fuel up. Should i have a vented gas cap? I thought I bought the right one.

There is a faint smell of gas around the gas door. Wonder if its trying to vent somewhere and cant.
So I looked into this a bit more. It appears that I am getting pressure build up, not suction from the tank. I know this because I have a vented gas cap that appears to be working. One way vent in.. not out.
I also noticed that my VCV valve is no longer hooked up so I suspect the canister routing is incorrect to some degree. Still trying to figure that out. In the mean time I buggered up my gas cap to allow venting both ways.
I have some other work to do on the motor and once that is done Im going to dig into this canister thing.
My guess is that the guy with the oringinal post here is expereincing the same build up and the bubbles are simply air seeping in.
I thought it was from the heat and was concerned...now I realize it was just by using a lot of gas in the tank and building up pressure.
Thanks for all of the help but Im under the notion that Im atlease safe at this point.
Jeff Chaumpa

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