Auxiliary fuel tank with an AUTO Fill/Stop??

[HenryJ]

Adding a timed latching relay could work. Make it adjustable though. I think five minutes would transfer more than 1/4 tank in my application.
The momentary switch was originally installed when my son was very young and curious. He seemed to copy everything that I did and I did not want him over filling the main for me. Since that install I have become very comfortable with the momentary switch. It is a light touch to activate the switch and energize the relay. I positioned it so that my arm rests on my knee. I know that a certain distance driven is roughly three to four gallons. A quick check and I can confirm it or add a little more. At first I thought it would be a pain, or painful to hold the button for a transfer. That was not the case. I did add an LED light. A visual indicator that the transfer pump has been activated. No sense holding the button with a bad switch, relay or fuse
The main tank gauge is very lethargic. The aux gauge that I added is much faster and more accurate. The gauge is from Dakota Digital and easily configured to work with various OEM senders and tank sizes.
My biggest investment was the gauge. The rest of the stuff was used parts and scrap metal. All together I bet I have about $150 invested.
I have been using this same sort of transfer configuration for ten years now. No regrets.

 

[PathNotTaken]

this is a great method. I used it on my old Tacoma and it worked fantastic. If you forget (which you WILL), it just continues to recirculate until you realize the pump is still on.

Little late to the party, but wouldn't this just flood the EVAP System, or maki filling slow?, or have issues with slow fill? My understanding is tanks have two vents, one thats for filling fast, and one that goes to the EVAP Canister. If you route the one for filling to the aux tank, wouldn't you end up with slow fills/no proper vent?

 

[Pntyrmvr]

You're asking for an update on a 13 year old post.

Long gone Saskatchewan.

 

[peekay]

Little late to the party, but wouldn't this just flood the EVAP System, or maki filling slow?, or have issues with slow fill? My understanding is tanks have two vents, one thats for filling fast, and one that goes to the EVAP Canister. If you route the one for filling to the aux tank, wouldn't you end up with slow fills/no proper vent?

It doesn't seem to do either of those things. I am guessing because the aux tank itself has a vent, there are no weird vacuum/pressure issues. The downside of my approach is that the factory system is no longer sealed because it is connected to the aux tank, the latter which has a vent to the outside. Every 2000 or so miles, I will throw an engine code. It's not a big deal. That being said, I have since replaced the Tacoma with a Tundra and still have the same tank. This time, I did not plumb it into the vent of the main tank, in part, because I didn't want to trigger check engine lights and have warranty issues on a new truck. I also did it in part because the Tundra has a 38 or 39 gallon tank so I didn't need to refill on the fly. Instead, I now have a gas pump and fill handle that looks like the ones from a gas station. This allows me to fill up the Tundra, or any other car.