AUX fuel tank with 4 lines instead of 2?

[Soylent]

Ok I think I know what these are but would be great if you guys can confirm. Big one is fill hose and metal 3/8” off sending unit is fuel supply to tank selector. Is the black 3/8” for an evaporative canister? The 1/4” is a return for fuel injection (which I don’t have). For now I’m going to cap those two since I have a vented cap but eventually Tee into the rear tank evap line.

Also, do I put permatex between the tank and the sending unit plate?

 

[Broncobowsher]

Top right is fill
Top center is emissions
Top left looks to be added on and is probably an attempt for a fill vent so the tank can be filled faster than a trickle.
Bottom is the fuel pickup.

 

[Soylent]

Top right is fill
Top center is emissions
Top left looks to be added on and is probably an attempt for a fill vent so the tank can be filled faster than a trickle.
Bottom is the fuel pickup.

So emissions 1/4” goes to my canister. The other 3/8 is similar to main tank where it runs up to the fuel cap with the large fill hose to burp as you say?

 

[Broncobowsher]

That is the best I can tell. I never owned an aux tank that fancy. Just a '69 that had a single filler neck that was impossible to fill and no emissions.

 

[DirtDonk]

Looks like a new tank? They are all designed to be kind of universal, because Ford changed the auxiliary tank over the years.
The early models didn’t have the large fill vent at all. Just the main fill and the, at the time, 5/16 fuel feed line.
Yours does look like 3/8, but you should double check it with samples of hose or maybe measuring, to make sure you’re using the right size hose.
Some Broncos did have 3/8” hose, and then converted to 5/16” at the pump outlet to carburetor. Others had 5/16 all the way.
But I’ve never actually confirmed that. Just some casual observations, without knowing whether the vehicle was modified from stock or not.

Sometime in the model year ‘70 the small emissions vent tube was added to go to the recovery tank and then up to the charcoal canister.
The fill vent could’ve been added about the same time, but I think it was a little before that.

What year is your bronco? Based on the picture of the old tank, looks like it’s a 70 or older?

 

[73azbronco]

my 73 had this, 3/8 was filler vent line like main tank.

After expending far to many brain cells trying to get the electric 2 tank valve to work, I went single 23 gallon tank, never looked back

 

[Soylent]

Looks like a new tank? They are all designed to be kind of universal, because Ford changed the auxiliary tank over the years.
The early models didn’t have the large fill vent at all. Just the main fill and the, at the time, 5/16 fuel feed line.
Yours does look like 3/8, but you should double check it with samples of hose or maybe measuring, to make sure you’re using the right size hose.
Some Broncos did have 3/8” hose, and then converted to 5/16” at the pump outlet to carburetor. Others had 5/16 all the way.
But I’ve never actually confirmed that. Just some casual observations, without knowing whether the vehicle was modified from stock or not.

Sometime in the model year ‘70 the small emissions vent tube was added to go to the recovery tank and then up to the charcoal canister.
The fill vent could’ve been added about the same time, but I think it was a little before that.

What year is your bronco? Based on the picture of the old tank, looks like it’s a 70 or older?

My truck is a 69. I purchased the aux tank kit from WH. Just ordered the metal filler neck from WH that has the vent line as the 69 is missing that for the front tank.