Using factory Aux switches

[old scout diesel]

It's probably been covered before, but here's my question. I want to install an aux fuel tank in the bed and wire a pump from it to the fuel tank. The truck previously had a tank as the owner left the holes in the bed and the "T" connector in the fill hose that a 3/8 hose can be connected to. I would like to use the aux switches in the truck (2015 3500 6.7TD, G56,8' box, 2WD) to control the pump and add a fuel guage to the tank to monitor it as well. I found the 4 electrical ports under the hood and have heard of hookup leads available to plug into them. Can this be done?

 

[Topzide]

Yes, there is a kit that has the plugs to also give you power under the dash. P/N 682099998AB is what you're looking for.
https://www.ebay.com/itm/374796005794

 

[JR]

There really isn't a need for a pump. I ran a gravity feed for years on my Gen 2. A normally closed solenoid valve would allow control of it while traveling down the road and any loss of power would close the valve, a good safety feature.

 

[Grumpy8811]

It's probably been covered before, but here's my question. I want to install an aux fuel tank in the bed and wire a pump from it to the fuel tank. The truck previously had a tank as the owner left the holes in the bed and the "T" connector in the fill hose that a 3/8 hose can be connected to. I would like to use the aux switches in the truck (2015 3500 6.7TD, G56,8' box, 2WD) to control the pump and add a fuel guage to the tank to monitor it as well. I found the 4 electrical ports under the hood and have heard of hookup leads available to plug into them. Can this be done?

you don't really need a fuel gage or a pump on an aux tank if it is gravity fed and the fuel valve is left open, you OEM tank will read FULL until you reach the point where you have used up all the fuel in the auxiliary tank and the level in the factory tank has started to fall and then the factory gage will start to move off full. At that point you know you will need fuel in another few hundred miles.

That is how I have operated for years now.. no pump, no gage, no wires... simple and EZ.

If I am concerned about the level in the Aux tank I have a homemade dipstick made out of plastic tubing.

 

[JR]

you don't really need a fuel gage or a pump on an aux tank if it is gravity fed and the fuel valve is left open, you OEM tank will read FULL until you reach the point where you have used up all the fuel in the auxiliary tank and the level in the factory tank has started to fall and then the factory gage will start to move off full. At that point you know you will need fuel in another few hundred miles.

That is how I have operated for years now.. no pump, no gage, no wires... simple and EZ.

If I am concerned about the level in the Aux tank I have a homemade dipstick made out of plastic tubing.

No ball check in the fill line? How does fuel not leak out of the fill cap? The Gen 4 fill caps are not exactly a sealed cap.

 

[Ozymandias]

They are a sealed cap, I forgot my auxilary pump more then once and never lost fuel out the cap.

 

[Topzide]

Or the fact that he may want to fill or vehicles, tractor or gensets from the tank. This what I've done with my tank. Haven't hooked up a gravity feed yet. Need to figure out how to filter the gravity feed. I want another water block filter before it goes in the factory tank. That little extra filtration may save me from a fuel headache. I know it's probably not needed, but I also run dual oil filters. Running 2 LF16035's. One is acting as a bypass with 10 - 20% flow. Was running an Amsoil bypass BP100, but price is getting up there, and since it's a dual filter mount, had to fill that spot with something! Will change both out with every oil change. Like the extra oil in the system!

 

[JR]

They are a sealed cap, I forgot my auxilary pump more then once and never lost fuel out the cap.

The gen4 is a push in cap with an o ring, nothing more. There is also a secondary flap down in the fill neck but it is metal on metal when closed, no seal. I'd personally not rely on either to prevent 50-100 gallons of fuel from spilling out the neck. Aside from the lost fuel that is an expensive clean up if it happens to be in a public area.

 

[Grumpy8811]

No ball check in the fill line? How does fuel not leak out of the fill cap? The Gen 4 fill caps are not exactly a sealed cap.

you know what, my ball check failed so it is just an inlet elbow now..
and it will fill the bottom tank right up to the flapper valve in the stock tank....( there are 2 flaps in the stock filler tube) but if if I know bottom tank is full, I close the top tank fuel valve.. and reopen it after I've burned off some fuel.. I've never actually lost any fuel, but I suspect it could happen if I didn't pay attention

 

[Ozymandias]

The gen4 is a push in cap with an o ring, nothing more. There is also a secondary flap down in the fill neck but it is metal on metal when closed, no seal. I'd personally not rely on either to prevent 50-100 gallons of fuel from spilling out the neck. Aside from the lost fuel that is an expensive clean up if it happens to be in a public area.

I know but it is sealed, you can't have fuel leaking out the tank in case of an accident with a roll over.

 

[old scout diesel]

Well, thanks for the many comments, all of which are very good. But I need to fill you in on the particulars. I have a side mounted fuel tank from a semi tractor that has a gauge mounting bung and several top mounted ports to suck fuel from, just like when it was mounted on the truck. I'm not sure I can remove the side mount drain plug for a gravity system and I may be leery about any contaminants in the bottom of the tank. I thought I might put a hose on one top port that has a long draw straw into the tank but an inch or so off the bottom. I can regulate the pump operation by monitoring the fuel tank level on the dash, when it gets to 3/4 full, I can shut the pump off. As I use out of the aux, I can know about when I need to fill one or both tanks. I picked up a new gauge sending unit in a junk shop last year that is adjustable, so that fills that thought easily. I am only concerned about filtration into the truck tank. Do I put a filter on the suction line, output line to the tank or both? And one of you mentioned a water filter. Would that be obtainable as an inline mount?
Sorry for the questions but I am looking at all this experience I've reading for the last 15 years and want to get it close to right the first time.

 

[Topzide]

With a pump adding fuel into stock tank, you'll want to put a filter on the out bound side going into stock tank. You can get filter mounts and filters at Tractor Supply and such. I use a water blocking filter on my aux tank setup. I keep an extra filter in the tool box for the aux tank, in case I get a batch of bad fuel! I put all fuel into aux tank, then fuel truck when needed. This way, I can buy fuel cheaper when finding it, and then fill truck or tractors. If I can figure filtration for a gravity feed system, I'd put a solenoid valve on the fill line. I wooden dowel rod is my fuel gauge for the aux tank. It's a L tank, worked the calculations for quantity left in tank. Close enough for my needs!

@old scout diesel, If you need more info, just ask. We'll try to help you get it figured out. It's nice to have that extra fuel to keep on gettin' down the road! Also helps in the wallet, when you can find cheaper fuel a few miles off the highway! Great project, keep us posted.

 

[Grumpy8811]

I am only concerned about filtration into the truck tank. Do I put a filter on the suction line, output line to the tank or both? And one of you mentioned a water filter. Would that be obtainable as an inline mount?
Sorry for the questions but I am looking at all this experience I've reading for the last 15 years and want to get it close to right the first time.

OK, simplest cheapest solution is just use any old inline filter like you'd use on a lawnmower for the line between the aux tank and the OEM tank, something like this . I wouldn't go overboard on this, because your truck already has a fuel filtration setup and fact of the matter is the water filtration is still performed by the stock setup. Auxiliary tanks do have a tendency to get condensation in them when left empty, especially if you live in a hot humid climate..

https://www.genosgarage.com/product...hpEUuhEboBkJjW2yDUFBIzZ8kc1vO2rxoCtlEQAvD_BwE

 

[AH64ID]

With a pump adding fuel into stock tank, you'll want to put a filter on the out bound side going into stock tank. You can get filter mounts and filters at Tractor Supply and such. I use a water blocking filter on my aux tank setup. I keep an extra filter in the tool box for the aux tank, in case I get a batch of bad fuel! I put all fuel into aux tank, then fuel truck when needed. This way, I can buy fuel cheaper when finding it, and then fill truck or tractors. If I can figure filtration for a gravity feed system, I'd put a solenoid valve on the fill line. I wooden dowel rod is my fuel gauge for the aux tank. It's a L tank, worked the calculations for quantity left in tank. Close enough for my needs!

@old scout diesel, If you need more info, just ask. We'll try to help you get it figured out. It's nice to have that extra fuel to keep on gettin' down the road! Also helps in the wallet, when you can find cheaper fuel a few miles off the highway! Great project, keep us posted.

Water blocking is 100% the way to go on an aux tank setup. The OEM f/w separator is excellent, but water blocking is better for aux tanks when you run a filter.

 

[reveldark]

Hey there! Water blocking filter is definitely worth the extra cost.