dual gas tank switch plumbing

[73kay]

Hey guys just got my 6 port dual fuel tank switch and I want to confirm
a few things:

1. Plumbing: I have 2x 16g tanks both with new 3 port sending units. I plan to plumb 3/8 lines from the tanks to the switch and then on to the mech fuel pump with no return. My delema is the return. I could just do the same thing with the return and pass it down to the vent pipe that will end at the charcoal canister and do its thing with no smells.

Or I could "t" the returns together and go directly to the canister. I'm
Leaning that way bc if the switch is selected on the left tank the right can't vent at all. Right? (I want to cap the 3rd "vent" tube out of the sending units bc I don't want the smell in the garage.)

2. Wiring: should be easy I have two gas gauges in the cab. (I know my left tank isn't setup yet. and I'm gonna use just a simple Knob switch to switch between tanks. So only one wire should be coming from the fuel selector to the dash switch.

3. Misc port: I guess this is just a "breather for the valve itself?

Thanks for your help. A lot of posts on this topic but my setup is a bit different.

[73kay]

Who doesn't like pix? Here is the dash

[BLE 'BURBAN]

You'll need to swap out your pump to one with a return line.
3/8" = fuel feed to pump/carb
5/16" = fuel return to tank
1/4" =vapor line to charcoal canister
the 1/4" vapor lines can be Tee'd together from the tanks to your charcoal vapor canister.

[rich weyand]

Does your fuel pump have a return? If it does, it has to be plumbed back to the tanks through the fuel tank switch. If not, I think you can just cork them at the senders.

The switch at the dash will always need two wires back to the fuel tank switch. The switch on the dash reverses the polarity of the two wires. You can't just hook one end to the frame.

[rich weyand]

One more note. You need to vent the vent connections on the senders, not the return connections. Run those to the canister and cap the return connections. That's assuming your fuel pump has no return. If it has the return, you have to hook it up through the fuel tank switch.

Why not vent the returns of the senders? The vent connection goes in the top of the tank and stops, so it always vents air. The returns on some senders go to the bottom of the tank, so you don't hear them running into the tank and think something is wrong. In that case, expansion in the tank (parking the truck outside on a hot day) will push raw fuel into the lines and into the canister, not just fumes.

I have no vent lines, but I have vented caps. No smell in the garage that I notice. You should get less than I do running the vents through the canister.

[73kay]

BLE 'BURBAN, thanks I wasn't sure about having both the vents on the switch one at a time.

rich, I was thinking of you when I wrote this post, recognize the tach? Haha but yes my pump has no return. So plug both return ports on the senders and the switch. For the vents I'll T them and route to the canister. Cool. Thanks about the return info good to know. Now I gotta finish cleaning out the vent line. It's been blocked since I got it. Compressed air has helped but it's still partially blocked.

As for the wiring the instructions that came with the book says that the switch has a default tank with no power supplied or like a light switch it's turned off. Then you turn the switch on and it transfers to the other tank. I'll try and take a pic of it for you. It's not an ac Delxo switch. Then with the other 4 wires 2x for send units and 2x gas gauges - at least that's what I gather from the diagram.


Thanks again for all your help!

[hatzie]

Your picture sure looks like the motorized pollack valve.
If it is you'll need a polarity reversing switch and it'll stay where you park it.

[rich weyand]

Originally Posted by 73kay

... rich, I was thinking of you when I wrote this post, recognize the tach? ....

As for the wiring the instructions that came with the book says that the switch has a default tank with no power supplied or like a light switch it's turned off. Then you turn the switch on and it transfers to the other tank. I'll try and take a pic of it for you. It's not an ac Delxo switch. Then with the other 4 wires 2x for send units and 2x gas gauges - at least that's what I gather from the diagram.

Yup, dash looked real familiar to me. Why, I saw a similar setup just this morning!

That sounds wrong. Should be TWO wires to the motor, two wires for sender units, and ONE wire to ONE gauge. Since with two gauges there is no need to switch senders, there is be no reason to connect them to the valve at all.

Post the diagram. I'll see if it's the same as mine. Or you can check the part number. That looks like Pollak 42-302.