auxilary fuel tank question(s) - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bigblock73 · 08-31-2003, 06:42 PM

Hey folks, I usually use the 73-87 side of the board, but this part of the board seems to get more traffic and maybe some of you have dealt/done with this before...

Since I am anticipating only getting about 10MPG (500+ HP 454, 4.10 gears, 700r4, and a heavy foot) my 16 gallon fuel capacity isn't going to get me very far on one tank of gas...so I might want to run an auxilary tank when the need arises. Right now I am in the finishing stages of plumbing the fuel system and I would like to plumb in a provision for adding a second tank (like a 20+ gallon removeable tank inside the bed). Now would be the best/easiest time to do so since the body is still off the frame.

What exactly do I need to do to run a second tank and how do i plumb it? Is it as simple as running a "T" off the main line with a switch and valve? Does anyone here have a similar setup? I am running 6AN (3/8") line for the entire fuel system, are there AN type fittings for this setup out there?

Thanks in advance...Jeff

*Gee_Emm* · 08-31-2003, 08:19 PM

The trucks I have seen with aux tanks have a "tap type of switch that is three way, so you could have 3 tanks but you don't need to. It works great the only downside is that your fuel guage wont show what is in your extra tank. The way I do it if I am carrying extra fuel is run off the aux tank then when it is empty(truck dies while going down the street) just reach down and switch the tank. I have an extra "tap" if you need one. $10 + shipping

bigblock73 · 08-31-2003, 08:26 PM

gee_emm, would you happen to have a pic of the switch? I am confused on the "tap" part. I also don't understand how the mechanics of the switch go, like where to mount it, how to run the lines so you can choose which tank you want to run, etc...

Would you put the cut-off valve (or whatever it is called) just behind the "T" in the line, that way when you switch tanks it cuts off fuel to the one line, and allows fuel from the other line?

I am primarily confused I guess when it comes to routing the lines and where the "valves" go.

Does anyone have a diagram possibly?

Sorry if I sound confused...I gues it because i am.

-Jeff

*Gee_Emm* · 08-31-2003, 08:35 PM

It usually mounts on the floor right beside the seat. This switch would be for 2 tanks, one line coming from one tank, one line coming from the other, and the third line running back to the engine.

**Richard** · 09-01-2003, 01:09 AM

A friend of mine had an auxiliary tank installed and it drains into the stock tank. No switches or shut off valves to deal with, when the secondary tank is full the gas gauge never reads less than full untill the primary tank starts being used up. Kind of a neat setup.

*Phillip Johnson* · 09-01-2003, 03:45 AM

10 mpg with a 500 hp 454? Are you dreaming? A 350 wont get much better than that!. How did you do it?? I have to know!

*Phillip Johnson* · 09-01-2003, 03:50 AM

As Richard said, You can buy a Fuel cell at the farm supply in Chico and they hold 105 gallons. i have one that I use for diesel. I think you could addapt one to flow into your main tank and that would get you quite a distance. Also, there is a Company called Transfer Flo in Chico Calif that makes custom tanks for ANYTHING.
Their number is 530-893-5209. They also have a website. Good luck.

lewi · 09-01-2003, 05:01 PM

In my 71 i removed the original tank, and used the two original aftermarket aux tanks (Saddle tanks). I had a local guys replumb the system. With a a flip of a small switch it changes from one tank to the other. If I'm running low on the left I switch over and the gas comes from the right, at the same time the fuel gauge shows me what is in the right side.......very nice.

Truckhead · 09-01-2003, 09:57 PM

These switchovers, which show proper fuel gauge readings as well as tank feed are often found on older pickups, at least the Fords, from the mid 70s to at least early 80s, due to the so-called "fuel shortages" dreamed up by the government and the oil companies.

mrein3 · 09-01-2003, 10:59 PM

Here's what I did.

When I bought Old Faithful the aux tank leaked. Of course the bolts were rusted beyond movement of the funky nuts they installed back then so I just ground the heads off the old bolts.

I had a local radiator shop repair the leak - yeah I'm a chicken. While the shop had the tank I ordered an aux fuel gauge from JC Whitney.

When I got the tank back I made up new bolts from 1/2" carriage bolts and 1/2 threaded rod. I also had to make a hole in the top of the tank for the new gauge. Since I was still a chicken I filled it with water and drilled out the hole.

My "tap" or switch or whatever you want to call the tank selector looks like what Gee_Emm posted only I have 3 in's and one out. The extra in is plugged with a bolt - I only have two tanks.

Attached is a picture of the aux. fuel guage from JC Whitney.

I asked the guy I bought the truck from how he knew how much gas was in the other tank. Similar to Gee_Emm's instructions he said run the saddle tank until the truck starts bucking. Then switch over. Then you know exactly how much gas is in the tank. I prefer the gauge.

08-31-2003, 06:42 PM	#1
bigblock73 yeller Join Date: Oct 2001 Location: Twin Cities Posts: 13,826	auxilary fuel tank question(s) Hey folks, I usually use the 73-87 side of the board, but this part of the board seems to get more traffic and maybe some of you have dealt/done with this before... Since I am anticipating only getting about 10MPG (500+ HP 454, 4.10 gears, 700r4, and a heavy foot) my 16 gallon fuel capacity isn't going to get me very far on one tank of gas...so I might want to run an auxilary tank when the need arises. Right now I am in the finishing stages of plumbing the fuel system and I would like to plumb in a provision for adding a second tank (like a 20+ gallon removeable tank inside the bed). Now would be the best/easiest time to do so since the body is still off the frame. What exactly do I need to do to run a second tank and how do i plumb it? Is it as simple as running a "T" off the main line with a switch and valve? Does anyone here have a similar setup? I am running 6AN (3/8") line for the entire fuel system, are there AN type fittings for this setup out there? Thanks in advance...Jeff

09-01-2003, 01:09 AM	#5
Richard Senior Member Join Date: Dec 1999 Location: Southern California Posts: 2,765	A friend of mine had an auxiliary tank installed and it drains into the stock tank. No switches or shut off valves to deal with, when the secondary tank is full the gas gauge never reads less than full untill the primary tank starts being used up. Kind of a neat setup. __________________ Richard 1972 K10 Custom Deluxe SWB Fleetside My build https://67-72chevytrucks.com/vboard/...d.php?t=800746

09-01-2003, 05:01 PM	#8
lewi Registered User Join Date: Nov 2002 Location: Redding California Posts: 223	In my 71 i removed the original tank, and used the two original aftermarket aux tanks (Saddle tanks). I had a local guys replumb the system. With a a flip of a small switch it changes from one tank to the other. If I'm running low on the left I switch over and the gas comes from the right, at the same time the fuel gauge shows me what is in the right side.......very nice. __________________ 1971 Chevy Cheyenne 383/350 LWB 2wd Built to use, and look good.

09-01-2003, 10:59 PM	#10
mrein3 Registered User Join Date: Feb 2000 Location: Center City, MN, USA Posts: 3,253	Here's what I did. When I bought Old Faithful the aux tank leaked. Of course the bolts were rusted beyond movement of the funky nuts they installed back then so I just ground the heads off the old bolts. I had a local radiator shop repair the leak - yeah I'm a chicken. While the shop had the tank I ordered an aux fuel gauge from JC Whitney. When I got the tank back I made up new bolts from 1/2" carriage bolts and 1/2 threaded rod. I also had to make a hole in the top of the tank for the new gauge. Since I was still a chicken I filled it with water and drilled out the hole. My "tap" or switch or whatever you want to call the tank selector looks like what Gee_Emm posted only I have 3 in's and one out. The extra in is plugged with a bolt - I only have two tanks. Attached is a picture of the aux. fuel guage from JC Whitney. I asked the guy I bought the truck from how he knew how much gas was in the other tank. Similar to Gee_Emm's instructions he said run the saddle tank until the truck starts bucking. Then switch over. Then you know exactly how much gas is in the tank. I prefer the gauge. Attached Images __________________ '70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN

08-31-2003, 08:19 PM	#2
Gee_Emm Account Suspended Join Date: Sep 2000 Posts: 4,002	The trucks I have seen with aux tanks have a "tap type of switch that is three way, so you could have 3 tanks but you don't need to. It works great the only downside is that your fuel guage wont show what is in your extra tank. The way I do it if I am carrying extra fuel is run off the aux tank then when it is empty(truck dies while going down the street) just reach down and switch the tank. I have an extra "tap" if you need one. $10 + shipping

08-31-2003, 08:26 PM	#3
bigblock73 yeller Join Date: Oct 2001 Location: Twin Cities Posts: 13,826	gee_emm, would you happen to have a pic of the switch? I am confused on the "tap" part. I also don't understand how the mechanics of the switch go, like where to mount it, how to run the lines so you can choose which tank you want to run, etc... Would you put the cut-off valve (or whatever it is called) just behind the "T" in the line, that way when you switch tanks it cuts off fuel to the one line, and allows fuel from the other line? I am primarily confused I guess when it comes to routing the lines and where the "valves" go. Does anyone have a diagram possibly? Sorry if I sound confused...I gues it because i am. -Jeff

08-31-2003, 08:35 PM	#4
Gee_Emm Account Suspended Join Date: Sep 2000 Posts: 4,002	It usually mounts on the floor right beside the seat. This switch would be for 2 tanks, one line coming from one tank, one line coming from the other, and the third line running back to the engine.

09-01-2003, 03:45 AM	#6
Phillip Johnson Account Suspended Join Date: Apr 2000 Location: Grants Pass, Oregon Posts: 1,580	10 mpg with a 500 hp 454? Are you dreaming? A 350 wont get much better than that!. How did you do it?? I have to know!

09-01-2003, 03:50 AM	#7
Phillip Johnson Account Suspended Join Date: Apr 2000 Location: Grants Pass, Oregon Posts: 1,580	As Richard said, You can buy a Fuel cell at the farm supply in Chico and they hold 105 gallons. i have one that I use for diesel. I think you could addapt one to flow into your main tank and that would get you quite a distance. Also, there is a Company called Transfer Flo in Chico Calif that makes custom tanks for ANYTHING. Their number is 530-893-5209. They also have a website. Good luck.

09-01-2003, 09:57 PM	#9
Truckhead 18436572 Join Date: Aug 2003 Location: Waynesboro, Va. Posts: 488	These switchovers, which show proper fuel gauge readings as well as tank feed are often found on older pickups, at least the Fords, from the mid 70s to at least early 80s, due to the so-called "fuel shortages" dreamed up by the government and the oil companies.



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