Sending unit 4 tubes

[Subb]

Hello everybody,
I got myself a new sending unit and I changed all the metal fuel pipes for copper from front to back. Unfortunately i don’t remember which tube is for the return fuel ( B or D)?
And do you guys know what that little ’filter’ is on the B end inside the tank?

Thankyou in advance
Gr

 

[Vbb199]

I think A is your gas filler neck spill return line
B is probably a vent
C is your fuel out line
D is your return

 

[Bextreme04]

I think A is your gas filler neck spill return line
B is probably a vent
C is your fuel out line
D is your return

This

Hello everybody,
I got myself a new sending unit and I changed all the metal fuel pipes for copper from front to back. Unfortunately i don’t remember which tube is for the return fuel ( B or D)?
And do you guys know what that little ’filter’ is on the B end inside the tank?

Thankyou in advance
Gr

The little module on the end of the vent tube is meant to prevent liquid fuel from going into the vent tube.

 

[Subb]

Thank you! I was abit doubting. So B is going to this ‘magic pot’ on the drivers left under the hood.
Any maintenance on this pot? That somebody know of?
I really appreciate this forum! Thankyou for the help

 

[legopnuematic]

That is the charcoal canister. Some (all?) have filter element on the bottom like this:

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[Bextreme04]

Thank you! I was abit doubting. So B is going to this ‘magic pot’ on the drivers left under the hood.
Any maintenance on this pot? That somebody know of?
I really appreciate this forum! Thankyou for the help

Yep, that's the charcoal canister that keeps the truck from stinking of fuel when it is parked. Looks like it needs to have most of those lines checked for dry rot and cracking. Looks like you might have one or more missing or cut lines as well. You should be able to see where all the lines go by looking at the emissions routing sticker somewhere on the air cleaner housing or the core support.

 

[75gmck25]

Depending on the year of the truck and the canister they used, there are also some vacuum lines and switches for the tank vent system. Basically they need to allow it to vent the tank by connecting to the carburetor, but only under certain conditions. If the venting was constant it would be like a big vacuum leak into the base of the carburetor.

Since you have three connections into the canister, one of them is probably the control line.