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home built fuel tanks?

colbystephens

colbystephens

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anyone done one? i've been thinking about building one for my blazer so that it would custom fit the bottom of the bed, but know so little about the tech of a fuel tank that i'm not sure where to start on design.

if i did it, i'd build it from steel because i don't have the know how or the tools to weld aluminum. what guage steel would be best to use?

i'd like to use the existing sending unit, so i guess i need to learn how those work. what's the minimum depth the tank could be for the stock sending unit to work?

what else needs to be considered when building a fuel tank? i've been looking at some of the ones in the summit catalogue and there's a few i really like, but i think i could build one for cheaper than $150 + shipping.

thoughts? ideas?
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BTW - I'm a blubie right now, so email me if you need to do the whole PM function....
 
The tank can't be any taller than the sender is otherwise when the sender reaches the lowest point your gauge will read empty even though you could still have half a tank of fuel depending on the depth of the tank. For instance, lets assume the tank is completely sqaure and is 18" tall but the sender is only 9" from the mounting surface to the lowest the float can go you would still have a 9" depth of fuel when your gauge shows empty.
 
I cant help too much, but if I were going to do this. I would probably cut out the center section of my existing or used tank and that way you wont have to come up with new mounts for the sending unit. Just build the tank around this center section. I would also build some baffles in it, like Nascar does so it doesnt slosh and get foamy, esp. on an off road rig. If you build one im sure others would be interested. I know one company makes 40gal. tank, but there was some reason I didnt like it, cant remember. oh well.

Good luck. Do a picture tutorial if you do. :D
 
4X4HIGH said:
The tank can't be any taller than the sender is otherwise when the sender reaches the lowest point your gauge will read empty even though you could still have half a tank of fuel depending on the depth of the tank. For instance, lets assume the tank is completely sqaure and is 18" tall but the sender is only 9" from the mounting surface to the lowest the float can go you would still have a 9" depth of fuel when your gauge shows empty.
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cool. thanks for that info. can you go into more detail as to how it works?

badmix said:
I cant help too much, but if I were going to do this. I would probably cut out the center section of my existing or used tank and that way you wont have to come up with new mounts for the sending unit. Just build the tank around this center section. I would also build some baffles in it, like Nascar does so it doesnt slosh and get foamy, esp. on an off road rig. If you build one im sure others would be interested. I know one company makes 40gal. tank, but there was some reason I didnt like it, cant remember. oh well.

Good luck. Do a picture tutorial if you do. :D
Click to expand...

if i do it, i'll definitely do pics and a write up, tho it will be specific to my truck because i'll be designing it around my roll cage. :) i'm looking for more like a 20 gallon tank. something a bit smaller and lightweight than the 31 gallon tank i have now. putting it in the bed of my blazer will get it out of bashing range too. :D
 
Not sure what you mean by "how it works". I can tell you that most GM sending units are 0-90 ohms, that means that when the float is at the bottom of the tank (empty) the ohm reading between ground and the sender wire would be zero, when the float is at the top of the tank (full) it should read 90 ohms between the ground and sender wire.
 
Colby this is coming from way back in the memory but I remember that AC delco made a universal sender that worked the same and was adjustable for the in tank depth. You needed a round hole for it to fit into the tank but then it just was a flange mount with sheet metal screws to hold it in place.

Let me google a little and see

Ding we have a winner
http://www.americanclassic.com/Google_Base_HTML_Pages/GTSU36-90-1936.htm
 
thanks for the link. pardon my ignorance, but it does say 90 ohm for aftermarket (not stock) fuel gauges - what's the required ohm rating for a stock gauge? it also says specific to 1936 gm trucks. what would be the reason for the specific to 1936? seems i could use it anyway. i didn't see a way to look up what it's shortest length was.

i'm hoping to be able to do a tank that's very short and wide (meaning, perhaps about 5" tall), but we'll see what parts require.
 
Maybe an angled bottom/sump? I've been throwing around the idea of a short wide one in the cargo area of the burb (enclosed and vented) between the wheel wells and shaving the bottom rear of the body for better departure...
 
jms said:
For 'wheeling, this seems counterintuitive, with respect to fuel pickup when the vehicle is at any angle.
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good point! thanks.

I didn't want to deal with doing a sump on it because i want it to sit flush on the floor back there. So I might have to do a taller, skinny tank. doing that would prevent me from having to make it beefy because it won't have to support any cargo loaded back there too.

what's the longest available sending unit? maybe i should just put a bung at the top and bottom of the tank and use some clear fuel line and just have it visible instead... hmmm.... :thinking:
 
I think the reason some tanks are made out of aluminum (or stainless) is so they don't corrode as much. If you just weld up a steel tank and don't have it galvanized or somehow protected, all the moisture that collects in the tank would rust it out pretty quickly.

Why not just use a stock 21 gallon 69-72 K5 tank? I've seen beer kegs used as well, but I've always wondered what the DOT thought about those.
 
yup, honestly Colby, $150 is freakin cheap compared to the materials and time you'll have into it...

first, stainless is HIGHLY recommended... it's the way to do it if your building a tank... steel is begging for many filter changes at some point..

without a doubt, you want/need to do baffles, ESPECIALLY in an offroad rig.. also, a sump is beneficial, and quite doable...

and, trust me, sending units, pickups, etc are easily available and doable up to 30" deep or more..

when the time comes, I'll have my tank guy make one up out of stainless.. not worth my time... it'll be an everything you could ask for, killer tank for $300 to 400.. I can EARN a ton more than that in the time it'd take me to fab one...
 
I'd use 16 gauge stainless to build a tank. You have to add baffles to keep the gas from sloshing around. Use SS wire and 95% Argon/5% CO2 and it will about the same as steel. You can use 75/25 but the 95/5 is stronger.
 
bp71k5 said:
I think the reason some tanks are made out of aluminum (or stainless) is so they don't corrode as much. If you just weld up a steel tank and don't have it galvanized or somehow protected, all the moisture that collects in the tank would rust it out pretty quickly.

Why not just use a stock 21 gallon 69-72 K5 tank? I've seen beer kegs used as well, but I've always wondered what the DOT thought about those.
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Does anyone have pics of a 21 gallon tank? Dimensions? That might be the ticket for me. I've wondered about the keg idea - but haven't given it any serious thought (for no particular reason).

ryoken said:
yup, honestly Colby, $150 is freakin cheap compared to the materials and time you'll have into it...

first, stainless is HIGHLY recommended... it's the way to do it if your building a tank... steel is begging for many filter changes at some point..

without a doubt, you want/need to do baffles, ESPECIALLY in an offroad rig.. also, a sump is beneficial, and quite doable...

and, trust me, sending units, pickups, etc are easily available and doable up to 30" deep or more..
Click to expand...

I don't think that $150 is expensive. I think it's a good price. However, i think that I could build something that would provide me a more custom fit for less than $150.

On another note, what do you think of those gas tank wall paints for steel tanks? Could I make it from regular steel and coat the inside with that stuff? I could build the box and then have the top bolt on and still have a real nice seal. This would allow me access to the inside of the tank to coat it. http://207.97.241.136/PRODUCTS/FUELSYSTEMRESTORATION/USSTANDARDFUELTANKSEALER/tabid/112/Default.aspx

I'll probably go the stainless route. Thanks for the tip on materials. I'll have to check into how much a spool of stainless wire costs.

Can someone give me some details on how to design the baffles? Could I just use some sort of foam like they do in the race cars? What kind of foam would work for my diesel? Who sells it? Can it just be the bottom few inches of the tank around the pick up?

VegasBruce said:
You can use 75/25 but the 95/5 is stronger.
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I've only got 75/25, and that's what I'm going to have to use. Any tips on how to do a good job with the less desirable shielding gas?
 
Just use it. Take some scrap and make a few practice passes, That is what I used at work for years. It actually welds nice. Don't grind the welds down. Just make sure to test it for leaks, before you fill it.

For baffles once you figure out the shape and size of the tank, put baffles to control the slosh. Its pretty simple when your looking at it. You want slow down the fuel side to side and front to back.
 
If you do make one yourself and plan to drive it on the highway at all, you may want to check whether it's DOT approved and legal if that matters.
 
bp71k5 said:
If you do make one yourself and plan to drive it on the highway at all, you may want to check whether it's DOT approved and legal if that matters.
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crap. you make a good point. guess i've got a bit more research to do...
 
Yea DOT is very picky. My dad wanted to mount a fuel cell on his trailer for our tractor instead of his truck but they wouldn't let him. Might wanna check into everything before you do it and can't use it.
 
I see people running beer keg gas tanks once in a while so maybe it's just one of those things that people take a chance with. I was seriously considering a fuel cell, but I got a brand new 21 gallon metal tank for $149 from LMC so that was cheap enough to not DIY.

I'm all for DIY, but I'd be worried about some kind of liability if the tank burst in an accident. At least if someone else built it, I could blame them if I got sued.
 
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