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Auxiliary Tank Rehab

Aptosgrown

Jr. Member
Joined
Jan 14, 2013
Messages
117
Loc.
Santa Cruz
Finally back at it after a couple years off.

I dropped the auxiliary tank as I was warned not to use it by the PO and it is full of crud. The plastic tank looks to be in good shape and it was basically empty other than the crud and about a pint of really old fuel.

My concern is the fuel setup. It is a '69 with a 302. The plastic tank is stamped FoMoCo. The tank has the sender and the fuel pickup. The fill hose is just a hose, no vent along with it. All of these enter through the rear of the tank.

Therefore there is no vent hose going to the tank. Is this normal based on the shape or something? There is only the large fuel hose you fill through, the fuel pickup line, and the sender.

I want to have an auxiliary tank because I want it. I know there are other options but I just want it. Do I need to get a different setup to have this effectively work with the stock system?

Thanks for the help, I'm excited to start on the project again.
 

Hotrodjohn

Full Member
Joined
Feb 12, 2016
Messages
264
Do you mean the filler neck vent hose? I believe all filler necks had the big fuel hose and the smaller 5/8 vent hose going to the tank. The later tanks, 71 and up I believe, had the small vent that went to the venting canister behind drivers seat. A 69 tank should have the big hole for pickup/sending unit, large hole for gas fill tube, and small hole for vent tube to filler neck.
 
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Aptosgrown

Aptosgrown

Jr. Member
Joined
Jan 14, 2013
Messages
117
Loc.
Santa Cruz
Hotrodjohn, thanks for the info, that was my expectation as well. I will try to post some pics.

The tank only has 2 holes total. The filler neck is just one large tube, it does not have a secondary tube attached, nor is there another tube attached to the tank. The tank has two holes only, the large filler tube and the large twist lock opening containing the sender and pickup.

The tank seemed to fit great but I am starting to think it could not stock, maybe the fact that it is plastic means it definitely wasn't?
 
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Aptosgrown

Aptosgrown

Jr. Member
Joined
Jan 14, 2013
Messages
117
Loc.
Santa Cruz
Here we go
 

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Hotrodjohn

Full Member
Joined
Feb 12, 2016
Messages
264
They, the front aux tanks, were all plastic tanks and that looks like it. Someone told me that the early ones actually didn't have a vent from the filler tube so that may be original, esp with the Fomoco on it. So the vent may have come along after 70 or so. It seems it would make it more difficult to fill up though. You could buy another tank kit from one of the vendors that would have a vent filler.
 

KeithKinPhx

Sr. Member
Joined
Jan 8, 2017
Messages
444
My factory original 68 auxilary tank is plastic. No filler vent hose. Called a "trickle tank" because if you fill at rate of anything more than a trickle it blows back and you get gas all over the side of the truck and ground.
 

NicksTrix

Bronco Guru
Joined
Aug 1, 2001
Messages
6,386
don't forget it had a vented cap back in the day and needs one when replacing cap.
 
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Aptosgrown

Aptosgrown

Jr. Member
Joined
Jan 14, 2013
Messages
117
Loc.
Santa Cruz
@Hotrodjohn & Keith - Thank you for filling me in, trickle tank it must be.

@Nick Thanks for the heads up, I could see how that could create a problem if not vented.

As I am poor, I am thinking of modifying the existing tank. Could I simply drill a hole and add a barbed nipple at the back of the tank towards the top and then just run a vent line?
 

KeithKinPhx

Sr. Member
Joined
Jan 8, 2017
Messages
444
You could put some sort of vent but where would you terminate it at? Shouldn't Just hang it inside the frame. I recently installed a 23 gallon main tank (video is on YouTube under Rising Phoenix Bronco) which has a vent line but I have to rig in a charcoal canister. I'll post that video when I'm done. I did not vent the Auxilary tank.

34 gallons of fuel should be enough I think ;)
 
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