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So I inhereted a T100 fuel tank. Physical mount (on the right, opposite the main tank) looks pretty straightforward with re-routing of the exhaust & muffler. Here are my questions:

1. Can I set up a 'spill-over" fill from one tank to another, so that I don't have to use a seperate filler or do I need to utilize a booty fab door on either the bed wall or in the bed (I'd really rather not).

2. I'd like to set up an automatic feed from one tank to another, so that the aux tank is always used first, as a feeder for the main tank? I would think then that my guage would always be full until the aux tank ran dry and I started drawing down the main tank. The pump would have to shut off automatically in this case.

3. If that isn't feasable, how about a switch for one tank or the other? And how do I switch the gas guage? I understand resistance must match between both senders, but tht's about all I know. I had an old Ford that had dual tanks, and when you switched from one to another the gas guage automatically reflected the level of whatever tank you were using.... how can I accomplish this?

I am an electrical rock, but I can follow instructions... I appreciate any ideas.
 

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Enteresting question.

1: Shouldn't be very hard to do. No higher than ouor fuel tanks are though would likely be dificult to fill on level ground or sloped towards the drivers side. Would require two hoses a filler hose and a vent hose from the auxilery tank. Would likely be easier to just get one of those pretty billet fuel doors and go that route and be able to fill from either side. Minor complication though the fuel return would still be pumping fuel into the main tanks.

2: Would be fairly complicated for a number of reasons. If the tanks were not plastic it wouldn't be to hard to just use them together. Just set them up like bif trucks with duel tanks and draw from one while they are bother linked together useing gravity. The flaw in this is it requires a low lying conection line and a conecting vent.

3: is the best option with right side fill. If the truck T100 has the same size motor as yours it is likely the fuel set up may be identical if not the pump assemly could likely be swaped for a tacoma set up. You would then need a switch and switching valve. A goos switch should have a set of poles for the tanks sending units.

You might try downey out about halfway down the page.
http://www.downeyoff-road.com/BodyComponents/AuxiliaryTanks.html
 

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valkyrie said:
So I inhereted a T100 fuel tank. Physical mount (on the right, opposite the main tank) looks pretty straightforward with re-routing of the exhaust & muffler. Here are my questions:

1. Can I set up a 'spill-over" fill from one tank to another, so that I don't have to use a seperate filler or do I need to utilize a booty fab door on either the bed wall or in the bed (I'd really rather not).

2. I'd like to set up an automatic feed from one tank to another, so that the aux tank is always used first, as a feeder for the main tank? I would think then that my guage would always be full until the aux tank ran dry and I started drawing down the main tank. The pump would have to shut off automatically in this case.

3. If that isn't feasable, how about a switch for one tank or the other? And how do I switch the gas guage? I understand resistance must match between both senders, but tht's about all I know. I had an old Ford that had dual tanks, and when you switched from one to another the gas guage automatically reflected the level of whatever tank you were using.... how can I accomplish this?

I am an electrical rock, but I can follow instructions... I appreciate any ideas.
here is a schematic of my setup:
http://community.webshots.com/photo/129985284/129985411bwJdvJ

1. spill over would be very very difficult. i guess in theory you can install a t-fitting. but you would have to make sure the flow resistance of second tank is very little. otherwise, the pump will always click as if it is full, i.e. you would have to stand there manually holding the gas pump while pumping very slowly. i know this bc when i installed my aux tank, i initially tried to t-fit the stock fill line with a slightly smaller diameter t-fitting. i ended with that exact aforementioned problem.

2. automatic feed is possible if the inlet on the stock tank is lower than the outlet on the aux tank. i believe the downey tank uses such a method. the thing that worries me is that with the fuel constantly saturating the stock tank, gas might go up the evap tube and f' up the evap canister, etc. this happens on my system and every 4-6000 miles, i will throw a ce light for evap canister malfunction.

another option (what i have), is to install an aux fuel pump (mine is a holley blue). this still results in the stock tank siphoning a little bit from the aux tank. to eliminate the overfilling problem completely, you can install one of those little electric valve things. i really don't think it's necessary though. the little amount of siphoning i get doesn't justify the added complexity.

one thing that does not show up on my schematic is a return line. this line goes from the fill/vent tube (the filler tube has two lines, one is the main filler tube, the other is to let the air escape as you are filling up) to the return inlet on the auxiliary. THIS IS A CRUCIAL LINE. it allows you to turn on the pump and not let it f' things up if you forget to turn the pump off. instead, the fuel will just recirculate back into the aux tank when the stock tank is full. trust me, you will forget to turn it off.


3. i considered using the stock gauge but then decided against it. first, it is a bitch and risk to mess with the stock gauge. the much easier route is to get an autometer gauge and mount it on the window pillar or somewhere else. now i can always tell the conditions of my tanks without having to mess with a switch and wait for the stock gauge calibrate itself.
 

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i would wire it to where the switch would use one one pole to switch the fuel pumps/valve and the other pole to switch between fuel sender signals for the tanks
 
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