More Dual Tank Questions

[Pancho]

I guess I'm just slow on the uptake but for the life of me I can't figure the purpose of the fuel tank switch mounted through the floorboard in my '73 Wagoneer. I mean, if both tanks fill from the same filler neck and the aux. tank gravity flows into the main tank which has the only gauge sender what would a person accomplish by moving the selector lever back and forth? Isolation of the rear tank to function as a very large jerry can? Is it even possible to run off the auxiliary tank independent of the front tank?
My system has been bypassed by the PO to only run out of the main tank. I'm trying to contact him to see if he bypassed the aux tank because of a leak or if it was too hard to fill or he doubted the accuracy of the gas gauge? I don't know.
I've dug through the site searching everything that I could find by searching but I haven't seen the answers to my questions.
Thanks in advance for your help.

[berettajeep]

I have dual tanks with a single fill on my '74 Cherokee. I also have the tank selector on the floor but mine has a toggle switch on the dash to see how much fuel is in each tank. I believe the original owner added that but maybe not.


The selector works on mine. Actually ran the one tank empty and switched it to the other and all was well.

Probably didn't help you any


Now I do need to figure out the vent line routing for them. I filled both tanks once and when it got close to full, fuel started pouring out of a line. But dropping both tanks does not sound like fun.

[Pancho]

So I finally got in touch with the PO of my '73. He said he didn't disconnect the back tank. It was like that when he got it. I suppose my best bet would be to reconnect the rear tank and see what leaks. I assume the disconnected tank is probably full since the filler hoses are still connected. The fuel might be pretty nasty but should mix with the fresh gas in the front tank, right? I also am guessing that when I unplug the hose from the back tank I should get fuel running out? The selector switch seems pretty loose. It may leak too. Someone said that those were still available through NAPA. I'll try to put it all back together this weekend after this next little batch of colder weather clears out.

[Carnuck]

I would hook up an exhaust hose or smoker to the tank and see if you hear/see anything escaping.

[threepiece]

I once mixed some old gasoline into my Wagoneer. It caused a change in my carburetor float system, presumably the seat on the valve. For a few weeks I had to tap on the carburetor with a wood block to free the valve and start the engine. The problem disappeared and has been working well for several years now.

[Pancho]

I guess I'll go lay under that thing and try to make sense of the modifications and figure out how to reassemble it all. They had a plastic bag duct taped around the filler hose too so I'm anticipating some seepage or leaks up there. All the emissions lines seem to be intact. Quien sabe?