Fuel tank venting questions

Sep 14, 2003
Yorktown, Va
Searched already, but have a couple of questions...

I have both the stock fuel tank as well as the Aux fuel tank in my 73 fj40, as well as an electric fuel pump for each tank. The tanks are both hooked to a Y-looking block which has a single output which goes to my engine (350).

On the stock fuel tank (OEM type), all my lines are capped except the one going to the filler neck. Similar to the first pictures here: <https://forum.ih8mud.com/showthread.php?t=74976&highlight=aux+tank+venting>
I have none of the fuel seperator equipment.

On the auxiliary tank, I have one hose for a vent (about a 2' piece) that right now is routed higher than the tank, and just exposed to air. My thought was that I could just vent the expanding air out.

On the maiden voyage to the paint shop, I filled both tanks, and whichever tank I was not sucking gas from, leaked. The stock one through the sender plate on the top (which I am going to seal) and the Aux tank from the vent hose.

My questions are;

1) If I take my vent hose from the Aux tank and hook it to a capped line on the stock tank, will this solve my venting problems?

2) If I did hook everything up like in (1) and got a vented gas cap for the stock tank filler, would this make it better?

3) If my thoughts above are totally wrong, what would anybody recommend?

Oct 8, 2003
Near Junk
I use the separator components so no expertise on your set-up. I have read many here just use the filler neck vent and no separator components.

In your set-up, why not just splice the vent hose from the Aux tank to the vent hose from the primary tank which then goes to the filler neck? Seems like an easy fix.

I've read mixed opinions on the vented gas cap. In the set-up described above I would assume you would need one.

Dec 7, 2005
I also have the same setup on my 78 with tbi. I vent through the main tank and have no problems.

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