Aux tank leak/fumes (1 Viewer)

[Igotmearedone]

Another novice question. The PO installed an aux tank that looks a bit similar to the manafre/SOR ones I see online but it has this valve on top of it. I can’t find any online for sale that look exactly like mine. But if I fill it past 10 gallons, fuel starts dumping out of it. All the ones this size look like they should be 22gallons or so. I don’t know much about these fuel tanks but this doesn’t sound safe and can’t possibly be what’s intended for it, right? Should I do anything to this to make it work better?

Also there’s always a gasoline fume smell whenever I’m working around the back that I’m wondering is from this valve thing too.

 

[B y r o n]

Looks like a vent line. Attach a hose and run it up higher with filter or tip over valve on the end and it should not leak any more.

 

[ducktapeguy]

Is it in the top center of the tank? x2 it's probably a vent line or return line, but if gas is coming out when it's half full maybe there's a pickup tube attached to it. It's looks like a normal hose elbow so essentially you have a hole in the top of your tank letting fumes escape. To hook it up correctly it should tie into your stock vent hoses on the main tank.

 

[SteveH]

Many aux tanks don't have a positive sealing gas cap, so the gas cap will provide venting.

You might be able to simply remove that fitting and installed a tapered pipe plug (with PTFE paste on it) into the hole, and seal it up. Not every PO's great idea.... was great.

 

[Igotmearedone]

Thanks for the replies. So I'm thinking my three options are:
1. Attach a hose to under the passenger side rear wheel well with a filter so it vents at a higher spot and maybe spill less
2. Assume it's a return line and hook up a return line from the carb to it and see what that does
3. Plug this hole and get a vented gas cap (right now have a non-vented one)

I guess I'll do some trial and error, probably in this order, unless someone thinks one of these is dangerous or not a good idea

 

[ducktapeguy]

What's your current setup look like? Is the main tank vented, does it have a return line, or are you using the Aux tank as the main tank? There are different ways of plumbing an aux tank, if you search for the conferr aux tank instructions they have all the diagrams, you just have to choose which one matches your setup. I just went through my whole fuel system to fix all the minor issues i was having with my dual tank setup, it's not that hard to get everything working correctly.

1. If you vent to a higher spot, that may or may not stop the spilling, but you'll still have the fumes. Not a great solution to have gas fumes escaping your vehicle, especially if you park in a garage
2. Does the main tank have a return line? Is the aux tank going through a selector valve or does it transfer to the main? If your carb and main tank have return lines, then your aux tank should have one too if it's being used as a second tank and not a transfer tank. It's not necessary to have the return going to the same tank as it's drawing from, but when you drive it's going to be returning gas to a different tank obviously.
3. Vented gas cap might prevent over pressurizing the tank, but if that's a vent hose then during fill up you'll probably have problems with fuel backing up the filler hose because the displaced air has nowhere to go.

 

[Igotmearedone]

I should have specified that it is the main tank. I guess I only called it an aux tank because of its placement and that’s what people selling them call it. There is no other tank in this set up. Also no return line.

 

[ducktapeguy]

If your return line from the carb isn't currently connected, it's probably meant to go that open port. That should fix your problems. But again you should also make sure you have a vent line from the tank connected to the charcoal cannister somewhere.