Dual fuel tank filling

MarineOne

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I am considering doing this setup for capacity on my 454 truck does anyone have a solution for running one sending unit and letting aux tank essentialy siphon to main tank? I was thinking weld on a -10 fitting with a 1 way check valve low on tank similar to a boat. Any feedback is appreciated or enjoy the dual tank filling tip.

This allows you to fill both tanks at the same time from either side of the truck. Instead of trying to market and sell them I decided to just give out instructions and pictures of how to build your own. This way I am not responsible for anything on your vehicle should you choose to undertake this endeavor. Besides I have gotten plenty of help over the years from the truck community and it's always great to give back. The reason they are split in the middle is a couple reasons. 1. It provides flexibility and 2. You can install and remove both sides without pulling the bed.

List of parts.

1. At least 72" inches of 2" Stainless tubing. If you don't use stainless you risk the insides rusting and getting in your fuel. 1.75 would probably work as well but I wanted 2" to make sure I had enough room for air as well as fuel.

2. Gates 23972 fuel filler hose. Comes in a 3 ft section. You will need to cut 5 couplers out of it 3.5" in length. If you want the tube a little closer to the frame cut 2 of them a little shorter depending on where you want your tube. Those will be your connections between the tank and the tube.

3. 10 2" hose clamps.

Instructions. Hope you can follow along with my brain and lack of phone typing skills. LOL. If not maybe pics will be better than my instructions.

1. Cut 2 30" sections off your 72" pipe. Cut the remaining section in half.

2. Measure 24 inches from the 2 30" sections and Mark it. Measure the inside diameter of the pipe you have and drill a hole with a hole saw to match at the 24" mark.

3. Using the 2 shorter sections notch one end of each to match up to your 30" pipe. There are lots of ways to make tubing notches. YouTube is your friend.

4. Weld the two pieces together to make your T-fitting.

5. Cut both of the shorter pieces to 2.25" from the inside of the long pipe.

6. Put everything together.

7. Depending on how level your setup is I made a couple stands and bolted them to the crossmember and then welded them to the tube level. I can give you measurements but most will be different I'm sure depending on where you put them.
 

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Grit dog

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The filler portion looks solid.
Tapping the bottom of the tanks for the siphon part is sketchy no matter how well you do it. Basically the reason that boats and motor vehicles haven’t had gravity drains on gasoline tanks in idk how long.
It’s fine until it becomes inherently unsafe.
JMO
 

85K304SPD

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Very clean looking. How do you put the bed on with the pipe on top of the frame? At least you wouldn't have to move the truck around to the other side at the gas station to fill up both tanks. Just use the original pick up tubes/ sending units that feed from the top, if you can get the bed on there.
 

MarineOne

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Well I've decided to move forward with the dual side filling and an aftermarket selector valve that utilizes factory pickup tubes and has two fuel pumps should work well for the efi setup
 

Scott91370

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The only issue I see with your fill-up system is that you may get fuel into the vapor line if it is still connected.
 

MarineOne

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The filler portion looks solid.
Tapping the bottom of the tanks for the siphon part is sketchy no matter how well you do it. Basically the reason that boats and motor vehicles haven’t had gravity drains on gasoline tanks in idk how long.
It’s fine until it becomes inherently unsafe.
JMO
I decides on fuel injection with 2 electric pumps but boats and tractor trailers still use the siphon method
 

SquareRoot

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Why not just spend a couple hundred bucks and buy new "factory" parts and run dual tanks like GM intended? I know everybody likes to save a buck and piece stuff together, I've done it many times. However, I have reached the point in life where I'm tired of doing S**t over to get it to work like I thought it should. If you plan on running EFI and want it safe and reliable, just do it right. I have done all this on my 85 K20. All new parts (baffled tank, sending unit, pumps, valves, switches) all of it is available and relatively cheap. Carry on.
 

MarineOne

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Why not just spend a couple hundred bucks and buy new "factory" parts and run dual tanks like GM intended? I know everybody likes to save a buck and piece stuff together, I've done it many times. However, I have reached the point in life where I'm tired of doing S**t over to get it to work like I thought it should. If you plan on running EFI and want it safe and reliable, just do it right. I have done all this on my 85 K20. All new parts (baffled tank, sending unit, pumps, valves, switches) all of it is available and relatively cheap. Carry on.
I'm making a system better than the problematic gm factory system... and the cross over filling is to beable to fill from both sides of the truck or for someone who only has a fuel door on one side but wants dual tanks. It shoukd had been like this from the factory. the childish sassiness is unnecessary from someone I'd assume is of an adult age... grow up man
 

SquareRoot

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I'm making a system better than the problematic gm factory system... and the cross over filling is to beable to fill from both sides of the truck or for someone who only has a fuel door on one side but wants dual tanks. It shoukd had been like this from the factory. the childish sassiness is unnecessary from someone I'd assume is of an adult age... grow up man
Have at it brother. Sounds like you got it all figured out.
 

Grit dog

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I decides on fuel injection with 2 electric pumps but boats and tractor trailers still use the siphon method
It’ll work. And even not leak if you do a good job of fitting bungs to the bottom of the tanks, but agree with the rest of the crowd, this is one of those dumb things that shouldn’t be done.
 

MarineOne

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It’ll work. And even not leak if you do a good job of fitting bungs to the bottom of the tanks, but agree with the rest of the crowd, this is one of those dumb things that shouldn’t be done.
Unless something were to hit them it'd be no issue. I've welded plenty of sumps to factory tanks. But efisystemspro has a switch valve that will do the job better and read fuel level from both tanks
 

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