fuel venting

[Ken B]

So the line with the white tape goes to the air cleaner, I understand and found where that connects. what I do not know is why is there a T in that line and were did or should it go? If not needed can I delete the T ?

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[Ken B]

Question #2
The very small pvc line with green tape, hard to see, does that go to the port on the carb with the green tape? Lots of tubes with screws plugging them that I didnt do so I am just trying to confirm and re plumb these lines

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[TexasMan81]

Charcoal

In what form? Burnt wood or some other form of incinerated substance?

 

[SquareRoot]

 

[Randy and Easton]

I need to make one of those. What did you use for the charcoal?

Sorry for late response, I used charcoal for fish tanks and it has worked fine, no smell


Randy and E

 

[Ken B]

Smart!

 

[Ken B]

I think I have all of the lines for vapor capture done , except 1....the line with green tape at the canister and another green tape near the other end. where does this connect.

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Didnt know if a carb pic would be helpful , there is a hose plugged with a screw that I need to figure out...unless that is where the last vapor line connects??

 

[Oldbear42]

In what form? Burnt wood or some other form of incinerated substance?

I have used charcoal from fish tank filters before (new not used). It comes in a fabric bag and seemed to work to remove soldering fumes sucked through a small fan.

 

[Ricko1966]

I think I have all of the lines for vapor capture done , except 1....the line with green tape at the canister and another green tape near the other end. where does this connect.

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Didnt know if a carb pic would be helpful , there is a hose plugged with a screw that I need to figure out...unless that is where the last vapor line connects??

That plugged hose is not tothe cannister. I forget where it goes I'll look tomorrow. I think it's labeled port b check your emissions sticker. Pull back on your pic so I can see both ends of the mystery hose. I think it goes to a nipple on the air cleaner.

 

[Daron58]

Ken,

we had same issue. PO did the charcoal canister delete 2 port sending unit as well. Found that same steel line under radiator shroud and PO cut it drivers side bottom and that was it. We smelled gas all the time and could not find at the time a canister. I made a small charcoal filter out of a fuel filter and a fuel vent and mounted it on drivers side firewall. Fixed the gas smell and have never looked back.

Not sure if that is what your wanting but here are a few pics

Randy and E

I understand the whole process but just wanted to ask if you just added the charcoal inside the glass filter housing around the center threaded with the filter screen inside or is there something I might be missing because the center that the filter ends screw onto doesn’t leave a lot of room for the charcoal and advise would be greatly appreciated Thanks

 

[Randy and Easton]

Yes, no filter, just the charcoal

 

[Randy and Easton]

I understand the whole process but just wanted to ask if you just added the charcoal inside the glass filter housing around the center threaded with the filter screen inside or is there something I might be missing because the center that the filter ends screw onto doesn’t leave a lot of room for the charcoal and advise would be greatly appreciated Thanks

Yes, sorry. No filter just charcoal

 

[eric8]

I think someone replaced the fuel sender with an early 2 port model.
AFAIK by late 70s they were 3 port.
Is there a problem you’re trying to solve or just thinking maybe your tank isn’t vented?

Hey I noticed you have a 77 Big Ten as well (same color!). How many ports does your sending unit have? Mine appears to have never had a return fuel line to the tank from the fuel pump, and of course our trucks had no evap, so I assume that just leaves one port on the sending unit and a vented fuel cap?

 

[Grit dog]

Hey I noticed you have a 77 Big Ten as well (same color!). How many ports does your sending unit have? Mine appears to have never had a return fuel line to the tank from the fuel pump, and of course our trucks had no evap, so I assume that just leaves one port on the sending unit and a vented fuel cap?

My 77 has 3 port sending units but 1 is capped off and the tank switching valve is an aftermarket 1 wire valve and one aftermarket tank. It was originally a single tank truck. Couldn’t say whether the fuel pump has a return line or not don’t recall. But the engine and sending units are not original.
I thought by 77 the factory was using a return line. But icbw.

 

[eric8]

I did some research and got underneath with a flashlight and some creative mirror work. Mine is a factory 2 port. OEM single tank, factory non ac, manual trans. One line goes from the tank to feed the fuel pump. Other line is a vent tube (3-4” long) that terminates into a vent cap, similar to what you’d see on a differential or transmission vent.

Apparently if square bodies had a return line it was dependent on how they were equipped. Bigger engines, a/t, a/c, etc would have the return to combat vapor lock. Other more basic combos did not have the return.

So looks like the venting takes place on my tank and non through the fuel cap. (Non vented cap, whether truck was equipped with evap or not, at least in ‘77)