Tundra Fuel Tank Swap?

You’re correct. I am aware that it could be dangerous. That’s actually why I chose air tanks. They are pressure vessels, and I tested the welds for leaks at 100psi. You wouldn’t want to put more than maybe 5 psi on a sheet metal fuel tank. I went with overkill everywhere I could think of. The main line connecting the two tanks is a hydraulic hose.

With that said, there are still plenty of cars and SUV’s on the road with aft axle tanks. Yes they have been crash tested, and mine hasn’t. I’ve already brainstormed through all of the possibilities. I then realized the obvious, the whole reason I was considering using this area for a tank is because I had already added a 4xinnovations rear bumper with a swing out. It has a honkin red gas tank mounted to it as well. I guess I was already asking for trouble there! Haha!

There is a very good reason for my madness so to speak. I live in eastern NC near Wilmington. Wilmington, NC is a damned hurricane target for some reason. After a storm, it’s anyone’s guess at when and where you will find gas. I also work for The State of NC, and I am REQUIRED to work during a state of emergency. I cannot evacuate. After Florence, I went through a tank of gas trying to find a path to work. I was finally able to contact my supervisor and I was sent to work at another location that I could get to. This is when I decided to upgrade my fuel capacity. Yes I have a snorkel, but it’s a truck, not a submarine. Flood waters with swift currents are no friggin joke, I stay away. In water that is just standing (no current) I will try it. As long as I can see the lines in the road, I know the road is there, as soon as the water is deep enough that the paint lines are not visible, I’m in reverse. The paint lines usually go out of sight when the water is near the doors, and I’m also not going to purposely flood the interior of my truck. These tanks also came in very handy with the recent pipeline incident. I was able to get a heads up to go get gas, thankfully. It’s nice to have the ability to drive away from a gas station with 37 gallons of gas at the drop of a hat. It was well over a week before I could purchase gas again. I’ll take the risk, it’s just too damn handy now. Most of the time my jerrycan is empty, but I use it to buy gas for my lawnmower and kubota and all my other things at the house that run on gas. Not having to remember to grab a gas can when leaving the house has its advantages as well. I’m guessing that the rear bumper should add some protection over the factory bumper, but it’s still dangerous I assume. DON’T REAR END ME DAMMIT!! Haha!

 

Nice truck and you can give training lessons on driving in deep water.

A VW TDI conversion would be a nice upgrade for torque and fuel economy, my Passat stock 2 litre burns about half the fuel of my 3.4v6, and it’s driven at much higher speeds. A little tune and the torque goes through the roof.

With your fuel capacity, I could go Halifax-Charlotte on one fillup. I left Halifax, stopped in Scranton overnight, was in Charlotte, the next afternoon for a stop, had dinner that night in Atlanta.

 

My best advice for driving in deep water is DON’T! Moving water is very powerful. People get killed after every storm we have trying to cross flood water. It’s happened where the water wasn’t that deep on the road, and then they hit the 10’ deep washout. That’s why I look for the lines in the road. If you can’t see the lines, there’s no guarantee that there is a road in front of you.

 

And cars float way better than people think. At least we’ll enough to float to where you don’t want to be.

 

Getting back to oversized tanks…

Before I took on the air tank conversion project, I thought about just removing the tank and fabricating one that’s bigger. There is actually a lot of room in front and in the rear for expansion, I have no idea how many gallons could be added that way. I even gave thought to welding extensions to my current tank. I decided against that because welding on a thin sheet metal tank is frustrating, and I don’t have a tig welder. Flammable fumes can easily be removed. I thought I ran across a company that made oversized tanks for our trucks, but they were all the hilux models from overseas. They were polymer tanks, and could probably be easily converted to gasoline tanks if the plastic was compatible with gasoline, but the evap system would have to be retrofitted to it, to keep the CEL off. I can’t remember what company that was, but they didn’t offer a “petrol” version, just diesel. Hell, the steering wheel is on the right hand side of those things, and how am I supposed to know what else is upside down, or backwards? The tank could be molded for the right side of the truck for all I know….and the prices are outrageous for ANY oversized fuel tank, spending that kind of money you would almost expect it to be installed as well. That’s why I took the DIY approach.

 

Sorry to bring up an old thread, but a 2nd factory tank fits on the passenger side if you bob the exhaust short and dump it to the side before the tank. I have 36 gallons capacity, the ability to switch between both tanks, one fill port, and I added a 2nd low fuel light on the dash for the 2nd tank. My best trip was 742 miles between fillups.

 

I’m in the low 600’s with my set up now. (On summer fuel) but my capacity is only 32.5 gallons. Everything has been working out great so far, but pictures of your installation would be awesome! The weight distributed evenly is very appealing to me. I feel like I have to have the truck leaning back to actually get a full tank of fuel, because of the tanks in the rear of the truck, and my transfer pumps on the top of the aux tank.

 

I thought about doing a transfer pump but im glad I decided to go with 2 pumps. I like having 2 separate fuel pumps ever since I lost one just outside Phoenix in july. Now I have the option to switch to the 2nd pump and make it off the highway at least.

It goes from each factory pump, converted to AN fittings, through a check valve, to a Y fitting, and converting the AN fittings back into into the factory feed line. It's all controlled by a single switch and relay. 1 pump is on the 87 spade and the 2nd pump is on the 87a spade so there's no interruption when switching tanks.

I redid my dash so now I have a low fuel light on the passenger side for the aux tank while the factory tank still works with the factory gage and low fuel light on the right side.

 

That’s a pretty cool setup. Mine only gives trouble filling, as the auxiliary pumps are connected to the top of the tanks. That means they are only helping fill the auxiliary tanks by pulling a vacuum on them, and I know they are full when they start pumping liquid (they get loud). The main tank and auxiliary are connected by a single 1/2” hydraulic hose at the bottom of the tanks, so they siphon into the main tank slowly as I use the fuel. Filling the tanks takes between 10-15 minutes waiting for the fuel to transfer through that 1/2” hose to the rear tanks. It’s expensive to fill up, but driving 80 miles per day, it’s nice to only have to worry about it once a week or so. I also have 2 jerrycans on the rear bumper, so I can have access to 42.5 gallons on any given day.

I only did this modification because of the scarcity of gasoline during hurricanes (and the stupid pipeline bs a few years back). I live near the coast of NC, and this setup has been handy in several events since I installed it. Everyone at the gas station normally yells at the person filling up 5 gas cans in the back of a truck, but doesn’t pay me any mind.

 

That’s pretty genius, would love to see more pics or a write-up. I have thoughts of doing an auxiliary tank in the spare tire location, but the plan was to have another fill neck I’d have to cut in and use a fuel pump on a switch to transfer fuel from the auxiliary tank to the main. Planned to add a fuel gauge in the cab for the second tank next to the switch to transfer fuel.

I still think that’s the route I’ll go if I do add the tank, but curious to see your setup, the biggest thing I’d love to do away with would be the second fill neck, so if you’ve got a way to do it, that’d be awesome to see how.

I also don’t want to reroute my exhaust, had issues cutting under the bed, caused a lot of corrosion on the frame and even got the bed so hot it’d melt a plastic cooler. Mine dumps over the spring behind the tire now. Doesn’t mean I couldn’t adopt your method and have a rear tank

 

Curious about this AN connection to the factory line. More pics?

 

That was the Expeditions West Gen 1.5 Tacoma of Overland Journal’s Scott Brady if my memory’s not wrong.

 

EVIL ENERGY 6AN Male to 3/8" Quick-Disconnect Female EFI Fuel Rail Fitting Aluminum

$13 EVIL ENERGY 6AN Male to 3/8" Quick-Disconnect Female EFI Fuel Rail Fitting Aluminum

https://www.amazon.com/dp/B07GB2R77C

 

I added a 1991 ford F150 tank where my spare tires used to be. It’s a 19 gallon tank but due to where the filler neck ended up and venting I can put 15 gallons in there so 33.5 total gallons or about 30 usable gallons.

the ford tank’s fuel pump pumps fuel into the stock tank. The aux tanks has its own gauge in the cab.

I’ve been using it for 9 years and about 85,000 miles. So far so good.

 

I hope to do the same, I saw you posting about this in the suburban gas tank thread a while back, still have it bookmarked
https://www.tacomaworld.com/threads/1st-gen-suburban-gas-tank-install.351918/

I’m trying to work out the filler neck, how it’s going to be accessible without going through the bed.

 

Yeah, when I had a bed on my truck I drilled a hole in the bed side. That corn of the bed had a big dent in it so I didn't care so much.

The filler neck is just behind the wheel well now.

 

I removed my filler neck and welded in a Y so I can choose which tank to fill.

 

I've thought about adding dry disconnects in the event I want to pump fuel to another vehicle. Like a motorcycle.

Another thing I've thought about doing is setting up a system where when the stock tank gets to like 1/2 full the aux tank pumps gas until the stock tank is 7/8 full and shuts itself off and when the aux tank is empty it shuts itself off. This could be on a on/off/on switch. One on being the auto and the other on being aux tank pump turns on manually.
I think this could be done with an arduino or something similar using the sending units of both tanks.

 

Funny, I spent forever looking for a Y I could use but never found anything I liked.
I have access to a welder and never thought of just making one....lack of imagination strikes again. With the camper the extra fuel door is no big deal. But a Y would have been much cleaner when I had a bed.

One thing I found was when the tanks were vented together if they were less than 25% or so full it would trigger a CEL with a slow evap leak code.
I pressure tested the aux tank, found no leaks and it held pressure.
If I clamped or removed the aux tank vent it wouldn't happen.
My guess is that with the extra air volume of both tanks with little gas in them it's a lot of empty space. So, when the truck does an evap system leak check there is so much extra air volume it thinks the extra air is a leak.

Does your Y keep the tanks isolated and separated? Have you ever had this issue?

 

Nice! Super clean!