1st gen suburban gas tank install

Hey all, long time listener first time caller. Purchased an 04 Tacoma back in March and been upgrading and playing with it ever since. Ive been getting a lot of good info for my purchases off this site as well as others but, TW seems to have to most condensed info out of them all. Figured it was time to contribute back with a project that I just got done doing. It seems people want a bit more range these days... and the only aux gas tank thread I came across was the guy on Expeditions West with the Izuzu Trooper tank.

In trying to duplicate his project I came across a Suburban tank that fit and gave me an extra 42 gallons vs. the Troopers 12(I think that's what it held) anyway its a lot more capacity. Figured I would share my build with everybody so if somebody wanted to do something similar they would at least have a starting point to go off of.

I found this tank at a junkyard for $50, but if you cant get one at a junkyard then monsterautoparts.com sells them new for $200. Its a 92-99 GM Suburban tank. Mine came with the bottom support straps and pump, not sure if the one online would come with the same. I will try and explain the process as best I can but, there is more than one way to skin a cat so you take what you want. I will answer any questions you guys have about the process. Just FYI the most complicated thing I did before this was install the supercharger so even though it looks daunting if you have basic mechanic/welding skills you can accomplish this. I am a fence contractor by trade so I have basic building skills nothing in the way of engineering by any means.

Ive included the pics that I stopped to take along the way, but I didn't take enough for a step by step instructional. I will post another post with an outline of what I did so you can get an idea of what your in for. I have a custom Deaver 10 pack on the rear, Im not sure the stock suspension will give you the clearance you would need, but I didn't try so it could work.

The tank is set up to pump fuel into my stock tank, I didn't want to mess with trying to pipe that thing into my main fuel system. Plus with the Supercharger it would take a bigger fuel pump probably which is just more money going towards the same goal as what I did.

Quick rundown:

Remove bed
Remove spare tire holder and crossbar
move towing hitch back a few inches
weld support brackets for tank
drill hole/weld small pipe in factory filler tube(removed from truck of course)
run wires/wire in pump with switch
cut hole in bed for filler tube
fab up a door for the filler tube

The only negative I can see to what I have done is the possibility of a Ford Pinto problem if I got rear ended. With my hitch and the bar I welded in the back I'm hoping that the frame will crumple under before it slams into the tank. Proceed with caution this is a custom job and not fully tested yet, but my clearance seems good so Im not worried about piercing it.

 

File this one under: Awesome.

Interesting angle to try and pump fuel into the aux tank.

 

A little more detailed explanation of the process.

1. Remove the bed, there are 6 bolts holding it on, make sure you disconnect the wiring harness from the rear lights and watch the stock filler neck as you remove the bed.

2. Remove the spare tire holder and crossbar, there are 10 or 12 bolts that hold that to the frame.

3. Remove the rear bumper and towing hitch. Believe it was 4 bolts that held those on.

4. Using the existing holes on the towing hitch and frame just slide it back a little bit to make more room for the tank. If you choose to scrap the towing bar realize that your frame will spread after you remove the cross bar and rear bumper so take a measurement of the frame or tack weld something on there to keep it the right distance. This is why kept my towing hitch on as it held the frame at the proper dimension.

5. Cut your exhaust behind the muffler and reroute it where you like, I have mine coming down before the axle.

6. Using ratchet straps hooked on the frame and running underneath the tank you can slide it around and get it positioned where you want it. I put a piece of steel across the top of the frame to keep the tank level with the top of the frame. The bed support in that spot sinks a little deeper than the top of the frame so be aware of that and make sure you your tank won't hit it. I found out when I put the bed back on that it hit and had to cut the support and make it shorter. Not a big deal but you can save yourself the time by learning from my mistake.

6. Weld brackets to the frame (or bolt) however you want to do it.

7. Remove the stock filler neck and drill a hole for welding in a tube that you connect a hose running to the pump.

8. Wire in the pump, it uses 4 wires(Purple-sending unit, Grey-power, Black w/White stripe-ground, and separate black tank ground). I used 14 gauge but I think they are 16 gauge from the pump harness. Make sure you wire in the 4th wire (black) to the frame for a ground. Put a fuse in between your switch and battery to prevent a surge. I wired in a gauge from O'rielly auto parts for my fuel level, make sure you get a GM gauge for this as it based on the Ohms for fuel level.

9. I moved my clutch start cancel and locker switch to down by the power ports in front of the shifters and have my light bar a fuel pump rocker switches in their old holes. The rockers I used required some filing on the sides of holes to fit but that was easy. The stock switches fit perfectly in the ports by the shifter. Just have to cut the harness and wire in extensions to get them over there.

10. Reinstall the stock filler neck and connect the hose from Aux gas tank pump. There are 2 pipes coming out, the larger one is the pump and the smaller one is the return. I cut the threaded nut off and used a hose clamp to hold the hose on as there is no pressure on the line now. I cut the end of the return line off and welded it into the stock filler neck. Just made sense as it was already there and had no other use now. I crimped the end remaining return line out of the pump to keep it from leaking.

11. Set the bed back on the truck so you can figure out where to cut a hole in your bed for the filler neck. I can get measurements later if somebody wants them, but I can't remember at the moment. I had to chop up the new filler tube to get it to fit but you can see from the bed pic that it will fit underneath the bed fine. About the only place you can run it where the tube won't be going up and down and around things which would make filling the tank a chore.

12. Pull bed back off and cut hole for filler tube. Cut down filler tube to fit as well and install it on the tank.

13. Reinstall bed and wiring harness for the tail lights.

I realize this is a pretty basic description but you guys can ask questions if you want to know more details. Enjoy your 58 gal total capacity, 1000 mile plus driving range depending on your foot and fuel economy.

 

Pretty sure the Tacomas hold 18 gallons not 12 stock. I know the 2nd gens hold 21 gallons.

Looks like a nice mod, but I would hate to have to top that 42 gallon sucker off! Could go a long ways though.

 

I was referring to the Trooper tank not the Tacoma

 

With both tanks full it would add close to 420 lbs but you could go over 1,000 miles between fillups.

 

Yeah I've read that gas weighs approx 6.3 lbs/gallon so with 60 gallons it comes out to about 380. I had my leafs made to give me 2" of lift with 400 lbs of weight. Pretty good rake empty but I'm putting a diff drop in the front soon and cranking my camburgs to 3" so it won't be so bad.

 

I believe there is also a skid plate available for this tank and with 42 gallons it's almost worth ditching the stock tank. I did this mod on my old 71 chev pickup and was nice to have a bit of range for the 454. You could also add on of the switching valves same as in many dual tank applications, they basicly switch everything over at once and no worries about forgetting you left the pump on in the big tank.

 

The dimensions of that tank are 13 1/8 inches deep. Does this hang down much? It looks pretty good in your pics but they're a bit dark.

http://www.1aauto.com/1992-97-fuel-..._content=FGT&gclid=CLaPoM7Y_8ECFasRMwod_RMAkA

I've been thinking of doing this with a smaller tank like a mid 80's F-50 Auxillary tank. I'm happy to see that someone was successful in this. You've provided a lot more additional information for my project. Thanks!

 

Good lord toting around that much extra weight in fuel seems like a waste to me.

 

OP, did you box and plate the rear of the frame? If you didn't, well, I wouldn't drive around with that tank more than half full.

 

If you consider what some people use their trucks for you might find it isn't a waste in some situations.

Another factor is the weight on the back part of the frame. Welded frame plates might be a good ideas as well.

For me I'd only use the aux tank when needed. For short trips I'd only use the main tank. The problem I've come across a few times is that I'm out in the middle of nowhere using 4wd and lo range pretty often getting 10mpg. I can only get so far before I'm at less than a half tank and need to refill. Twice in SoCal and once in Arkansas that meant a major change in plans as the nearest gas stations were far enough away to be a real drag. Part of this was poor planning, but I'd like a nice safe margin of error. Also I should add that two future trips are driving to Alaska and driving to the tip of Baja. Having extra fuel capacity on both trips would have huge advantages.

For regular highway driving I have a range of about 260 miles on a full tank of gas. Averaging 65mph this would take about 4 hours. I'm totally fine with driving 12 hours a day, but I like to stop and take a break every few hours. So refilling on the highway is no big deal. It's the back country trips that are a pain in the butt.

The solution is either better planning, a different vehicle or carry more gas. Part of better planning is eliminating miles and not going to places I want to visit...not happening. Also I want a better margin of error and I'd have extra gas to share should I find another person low on gas in a remote location. Changing vehicles isn't happening either. So...how to carry more gas?

I've considered gas cans, like jerrycans. I have a camper shell on the back with a platform for sleeping. I'd rather not carry gas back there because that is where we sleep. We like this sleeping arrangement. We also like tents, but they're more of a pain and take time to set up and take down. Plus we can sleep in urban areas in the bed. A rooftop tent raises the center of gravity and increases drag. Plus the cost is money I could use to actually go places.
I could use a hitch mounted cargo carrier for the cans but that would mess with my departure angles way too much. I could carry them on the roof, but I'd like to keep my center of gravity lower and the extra drag (like the RTT) will eat into my gas mileage more than I'd like. I could also get an off road bumper with a swing out to carry my gas cans, but to me, this would cost too much and on road trips I'm accessing items in the bed fairly often. All this leaves the aux fuel tank as the best option.

As for the spare tire, I'm rebuilding my sleeping platform with a drawer system and a spot in front of the passenger side wheel well for the spare tire to live.

The other thing about this is that it's just a fun project to do.

 

Oh so you're doing dual tanks? That's not a bad idea, especially if you do any wheeling. Much easier than having to carry extra gas cans that's for sure.

 

I did not box it, I am going to put on a relentless fab rear bumper in the future so at that time I will scrap both the bumper and cut off the part of the hitch that I don't need and weld in better bracing on the rear. In the phase of testing it at full capacity at the moment to see how things react. So far so good

 

I can get you a measurement if you like, tell me where you would like to see a measurement from and I will post it, I never had a spare tire under there so I cannot say how it hangs compared to what that would of been. It seems to be well tucked in there to me, I believe my receiver hitch hangs lower than the tank

 

Headed to Baja in March with a friend, heard gas stations can be few and far in between sometimes so I am going with better to have and not need than to need and not have.

 

I applaud your ingenuity but this mod turns your truck into a version of those deadly ford pinto where any rear end collision turns your truck into a firebomb death trap.

you would be much better served by just getting an aluminum 24 or 30 gallon gas tank with built in fuel pump (they cost about $150) and bolt it in the bed and hook up your fuel lines to it and call it a day.

I just think a gas tank needs more protection then sitting right behind the back bumper

 

Pretty cool mod. Something to think about is the collection of condensation inside the tank when leaving it empty... its better to store it full (and use the fuel so it doesn't go bad). I don't know how much this would be a problem in reality.

 

Yeah I made mention of that in the original post, a lot of the pinto problem was overall design of the gas tank as well. Ive been told that the suburban gas tanks sit right at the back of those vehicles and don't seem to have issues. Overall yes though this is my only concern that I have with this myself, but when I get my new rear bumper and see what kind of room that leaves me I am going to fab in some better supports and bracing to limit any chance of this happening.

 

It isn't any different than people toting around heavy aftermarket bumpers, skid plates, winches, sliders, roof top tents, hi-lift jacks and oversized E-rated tires all in an effort to look cool. At least the gas will eventually be used.