Gasoline in vapor canister

[1980 Big Ten]

1980 Big 10 running great but smelling gas in the cab. Lifted the hood to find gasoline dripping out of the driver side vapor canister. I assume that means that pressure is pulling gas from the tank to the canister. Any obvious causes or things to check first? Here is the pic of the schematic. Thanks!

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[bedwards]

Do you have dual tanks? My '85 did a similar thing. The 6port valve was either leaking or hanging part way. It was literally pumping fuel from the driver tank to the passenger tank. When that tank got full it pumped it into the vapor lines and canister. It was dripping out of the line that goes to the carb. When I took the passenger tank cap off, gas ran out and I caught about 2-3 gallons in a bucket. Very dangerous. Replacing the selector valve fixed.
Have you checked for gas in your oil? May also be a bad fuel pump.

 

[1980 Big Ten]

Thanks for the reply. I do have dual tanks and I’ve been wrestling with problems from the start of this project. I have a 3-port valve and my mechanic is wondering whether that’s the problem and whether to replace with 6-port. If you had problems with 6-port then I might have other problems too.


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[gotyourgoat]

There was a rash of tank switch failures causing problems like this a couple months back around here. Switch was failing and gas was being pushed through the opposite tank, return lines, overflowing the tank, carb and the canister. Basically anywhere it could get.

Am I reading that rounting schematic right, It looks like there's 2 canisters?

 

[1980 Big Ten]

I’ve heard a lot about tank switch failures and people going to one tank. Seems like we could get this right by now. Yes, I have two canisters—one for each tank I think.


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[bedwards]

ONce the gas gets in the canister, it's ruined. I bought a new canister from Rockauto on closeout cheap.

 

[Wildjoe330]

I have the same kind of things going on. My second gas tank is a custom tank from the 60's You can smell gas around the Truck sometimes and I have been 2 busy to think about it much. My brother caught me by surprise and said the same he smelled gas and is the a canister problem?

I was more worried about the filler tube spout when you try to fill it with gas it won't take it it just clicks off or sprays out gas at you (it does it on both sides) so I was wanting to update both sides with larger filler tubes so you could fill it up without spills. 77 gas filler tube, the tube just narrows down to nothing so that it won't take gas very well. No matter how hard I try this post won't edit down to one pic.

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[USNTex]

My truck experienced a similar problem a couple of days ago. When I've switched tanks its always died after a few minutes. I thought the gauge must be faulty and filled up the 2nd tank. Drove about a mile and truck died at a stop light at idle, and I switched back to the "good" tank. Got it going and drove another 4 miles no problem. Took it out that day again and it died again at idle and this time I noticed gas leaking out of the passenger side of the carb,

I figured I just needed to rebuild the carb since I've driven it more in the last week than its been driven in 6 months or more. But I haven't switched the tanks since then either. And its been starting no problem the last 4 times I've taken it out since I haven't switched the tanks.

 

[1980 Big Ten]

Do you have dual tanks? My '85 did a similar thing. The 6port valve was either leaking or hanging part way. It was literally pumping fuel from the driver tank to the passenger tank. When that tank got full it pumped it into the vapor lines and canister. It was dripping out of the line that goes to the carb. When I took the passenger tank cap off, gas ran out and I caught about 2-3 gallons in a bucket. Very dangerous. Replacing the selector valve fixed.
Have you checked for gas in your oil? May also be a bad fuel pump.

Thanks for the reply. My mechanic wants to replace my 3-port with a 6-port but isn’t certain it will solve the problem. Your post suggests the problem is likely elsewhere. Can you give me more details about replacing the selector valve?


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[bedwards]

I don't know what the difference is in the 3 and 6 port valves plumbing, but I can assure you that was the problem with mine. I took the valve apart out of curiosity and it appeared to be leaking internally. Still it would take a big leak to pump from one tank to the other. That's why I wonder if it hung up between ports. It put enough extra gas down the carb that I had to clean the soot off the plugs.

upon edit, I don't see how you could make a 6 port work where you had a 3 port. You would have to cap some of the ports and that seems dangerous in itself.

 

[Wildjoe330]

I put a electric fuel pump on mine so it wouldn't vapor lock on me.
when it's hot outside and my squarebody wants to vapor lock I turn
on the electric fuel pump and she keeps running.

I was tending to leave it on all the time and it seems to pressure up
to the canister and it has put out black exhaust on the ground from being
too rich. Can't don't leave the electric fuel pump on all the time.

 

[Rusty Nail]

You know there is a filter in that charcoal canister....maybe yours is plugged up yo? They cost about two dollars.

Why else would you have liquid gasoline in a place meant for VAPORS? This is DANGEROUS.

Hit it Biz!
Tell em bout it!

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