Auxiliary fuel tanks

[Sneezy]

Has anyone added an auxiliary in bed fuel tank? I drive a lot of miles and I’ve been researching ones that are in the 50-75 gallon range as I’m tired of filling up every day. I usually go through about 5/8 of a tank of fuel per day and would like to only have to fill up once per week. Unfortunately I only have the 26 gallon tank as the larger tank wasn’t available since I didn’t have time to order my truck and had to buy it off the lot.


If you have added one I’m curious how you plumbed yours in, or opinions on the best way to plumb it. I can also just go the route of not plumbing it in and have one of those transfer pumps that are just like a regular gas pump nozzle that you’d just top off the tank through the fill neck. I’m not really sure which route I prefer. My dad’s previous F350 he had one of his upfitter switches wired to switch from one tank to the other, and another switch was used to transfer fuel between the tanks. This was super convenient and he could go over 1000 miles while towing without doing anything but flip a switch when the primary tank got low. But there is added complexity in going that route as well so I’m torn at the moment

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[HammaMan]

Damn, how many daily miles we talking here?

You could make a setup to do this. Not aware of any off the shelf products. Ideally you'd want to create a solution where either you're transferring externally via shutoff style pump handle (traditional bed tank w/ pump), or you've put something into the tank that when ~4/5 full or similar a siphon vent tube from your bed tank begins to pull fuel back in if you forget to turn it off or the gauge lags. Another option would be a timing circuit to run a pump for a specific amount of time that'd transfer ~8 gallons in a minute type of thing and run for exactly a minute.

 

[Sneezy]

Damn, how many daily miles we talking here?

You could make a setup to do this. Not aware of any off the shelf products. Ideally you'd want to create a solution where either you're transferring externally via shutoff style pump handle (traditional bed tank w/ pump), or you've put something into the tank that when ~4/5 full or similar a siphon vent tube from your bed tank begins to pull fuel back in if you forget to turn it off or the gauge lags. Another option would be a timing circuit to run a pump for a specific amount of time that'd transfer ~8 gallons in a minute type of thing and run for exactly a minute.

I usually average around 250 miles per day +/- 50 miles. So something where I could get 1000+ miles of range would be nice.

I like the idea of a siphon type setup since it’s simple and there are no pumps to fail. I’m not sure how to set something like that up though to where it would reliably pull fuel once the tank drops below a certain level. I haven’t dropped the tank yet to see what we’re dealing with as far as having extra room to add an additional fitting to the fuel tank sender/pickup. Im waiting on my warranty to expire before I hack into it, but considering I’ve racked up 10,000 miles on the odometer in the 2 months I’ve had it, my bumper to bumper warranty should be up by spring time ??

 

[HammaMan]

Damn, almost perfect for EV territory, especially if gas is on you. 250 miles comes out to about $4 worth of electrons w/ my PoCo. Don't even need 8 hours on the charger to get it too, and the house is the 'gas' station.

 

[Sneezy]

Damn, almost perfect for EV territory, especially if gas is on you. 250 miles comes out to about $4 worth of electrons w/ my PoCo. Don't even need 8 hours on the charger to get it too, and the house is the 'gas' station.

I did entertain the idea of a Lightning, since I haul 1000+ lbs of payload everyday, but it’s not really practical for me since I can’t charge at home. I live on my boat when I’m in town for work, and I have 20 acres and a cabin in the woods, but it’s really rural and totally off grid. I do have a generator and solar grid but it only gets about 4-6 hours of usable sunlight per day between the trees, which is fine to run the cabin, but definitely can’t charge a vehicle. So it just didn’t make sense with today’s technology

 

[Gros Ventre]

Are you diesel or gasoline? Makes a difference. I put in a 60g in bed gas aux tank. Plumbed it in through a pump to the vent line next to the main tank fill line. Note that you do need a vent line in addition to the pump line. I find the fuel level gauge operates funny. The "miles to empty" actually tells me more about the actual main tank level. Its as if the computer doesn't believe the level can go up while on the road. One side benefit to the range is that with such a tank you can save on the order of 30-50¢/g by finding the lowest price gas in your state. I chose the 60g tank since its height is low enough to allow a toneau to be put on the bed.

 

[Sneezy]

Are you diesel or gasoline? Makes a difference. I put in a 60g in bed gas aux tank. Plumbed it in through a pump to the vent line next to the main tank fill line. Note that you do need a vent line in addition to the pump line. I find the fuel level gauge operates funny. The "miles to empty" actually tells me more about the actual main tank level. Its as if the computer doesn't believe the level can go up while on the road. One side benefit to the range is that with such a tank you can save on the order of 30-50¢/g by finding the lowest price gas in your state. I chose the 60g tank since its height is low enough to allow a toneau to be put on the bed.

I like your thinking! Mine is also gas, I wish Ford still offered the Powerstroke and didn’t limit it to certain trim levels. That’s a conversation for another day though ?

I like your idea of just using the existing vent line to add a pump in line that will fill the tank. Where did you route the new vent that is needed?

 

[Gros Ventre]

I like your thinking! Mine is also gas, I wish Ford still offered the Powerstroke and didn’t limit it to certain trim levels. That’s a conversation for another day though ?

I like your idea of just using the existing vent line to add a pump in line that will fill the tank. Where did you route the new vent that is needed?

My aux tank has a vent line outlet near the pump suction line. I drilled another hole in the bed wall and routed it down adjacent to the pump suction line. I teed both into the fuel tank vent line next to the fuel filler pipe. I put the vent line a couple of inches above where the pump outlet was teed in.

 

[Sneezy]

My aux tank has a vent line outlet near the pump suction line. I drilled another hole in the bed wall and routed it down adjacent to the pump suction line. I teed both into the fuel tank vent line next to the fuel filler pipe. I put the vent line a couple of inches above where the pump outlet was teed in.

That makes sense, thanks for the info to help steer me in the right direction ??

 

[jmh86325]

I did entertain the idea of a Lightning, since I haul 1000+ lbs of payload everyday, but it’s not really practical for me since I can’t charge at home. I live on my boat when I’m in town for work, and I have 20 acres and a cabin in the woods, but it’s really rural and totally off grid. I do have a generator and solar grid but it only gets about 4-6 hours of usable sunlight per day between the trees, which is fine to run the cabin, but definitely can’t charge a vehicle. So it just didn’t make sense with today’s technology

You need a Powerboost so you can charge your Lightning ...LOL

 

[John861]

Have you considered swapping in a 36 gallon tank? If you have a longer wheelbase truck, the 26 gallon is the same physical size as the 36. The 26 just has a lower shutoff height. Should be quick and easy to get an extra 10 gallons.

I don't know exactly which wheelbases share the tanks. Clearly not a regular cab short bed, but I don't know more than that. You would also want to update the IPC, which Forscan can probably do.

 

[huhner5]

https://www.northerntool.com/produc...-2012-model-011025-3490901#hotbar-description

Been using this kit for 10+ yrs in our pickups that pull our snowmobile trailers out west... granted they have all been diesels.. but a super simple way to plumb.. only flows when it needs it...

 

[Buyer2021]

Note that when dealing with in-bed auxiliary fuel tanks for gasoline, only external refuling systems (pump the fuel from the aux tank to the OE tank with a hose and auto-shutoff nozzle via the OE filler) are fully DOT legal for a variety of very good and prudent safety reasons.

Transfer Flow, Inc. is probably one of, if not The, most reputable manufacturers of auxiliary fuel tank systems and their website has a wealth of resources about safe and legal systems. I especially recommend reading the pages on Fuel Regulations and all of the FAQs.

@Sneezy, gasoline is inherently dangerous stuff, it's not the same as diesel, you drive many miles more than most of us, wishing you safe travels for every one of them

 

[Gros Ventre]

Note that when dealing with in-bed auxiliary fuel tanks for gasoline, only external refuling systems (pump the fuel from the aux tank to the OE tank with a hose and auto-shutoff nozzle via the OE filler) are fully DOT legal for a variety of very good and prudent safety reasons.

Transfer Flow, Inc. is probably one of, if not The, most reputable manufacturers of auxiliary fuel tank systems and their website has a wealth of resources about safe and legal systems. I especially recommend reading the pages on Fuel Regulations and all of the FAQs.

@Sneezy, gasoline is inherently dangerous stuff, it's not the same as diesel, you drive many miles more than most of us, wishing you safe travels for every one of them

That's not true. There are some companies that offer gas aux tanks to plumb into the trucks fuel system. What is required is that the aux gas tank has a siphon preventer valve in it and the aux fuel pump suction line comes out the top of the tank. (EG It is legal for a diesel tank to feed from the bottom of the tank but not a gas version.)
Go look at Leonard Online Truck Accessories.

 

[Aron]

Another thing to consider is the hit to payload for something like this. Gasoline is roughly 6 lbs per gallon, so another 75 gallons would be 450 lbs, plus the weight of the pump/tank equipment, plus the 1000+ lbs of gear that you said that you are already are carrying. This would exceed the payload limit on many (but not all) F-150s once you include a driver.

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