26 to 36 gallon fuel tank swap

[rustyrider]

Does anyone know if they modified the reserve on the 2021s? I looked this before when I first got my truck, but everyone said the reserve was +/-5 gals. Anyone confirm? I'd hate to do the swap and fill up with 100 mile DTE but the gauge saying the tank is "empty."

Looks like you're on to something. I stumbled across a thread speaking about the "unadvertised reserve" on our trucks (on the other forum). The advertised volume of the tank is actually less than what it actually holds. Without looking up the thread from the other forum, the owner's manual does indicate an unspecified reserve beyond the advertised tank size (I personally didn't search this out in the manual, but another member quoted the manual.) Good to know, but it would also be useful to know what the actual usable fuel volume is.

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[Bocephus]

We aren't connecting. I view the tank as either a 26 gallon tank or a 36 gallon tank. I don't think in terms of reserve amount of fuel left. I'm not brave enough to run the truck to zero miles to empty and then see how much further it will actually go (and it would vary anyway, depending on conditions). I do know however how to figure what's left if the tank if starts from full and I'm getting 10mpg.

edit: I missed the part about you saying you would like to do the swap yourself. It appears one of the members on the other forum may have figured it out. Even if he didn't, someone will shortly, I'm sure. They're figuring out pretty much everything in Forscan.

BTW, if you need part numbers, I was able to get mine locally from two different dealers. They confirmed the part number for the fuel pump independently from each other. Also, my truck is a 5.0l coyote truck. If you need a part number for the extended range fuel pump for that, I can give it to you.

ML3Z-9H307-B

I found the best place (with some searching) to buy the pump was at Blue Springs Ford. Even though the pump was a little more than tasca parts or levitown parts, shipping was half the price as the other two so the price came out less. I ordered the pump and a new lock ring and gasket so the new tank will be ready to go without breaking down the old tank. That way, if I have a shop do it, the labor should be a little less. I've done a fuel pump change before on an F150 and while I can do it, it's hard to do laying on the driveway, at least for a 64 year old guy.

So have you done the tank swap, and if so, how did it come out?

 

[rustyrider]

So have you done the tank swap, and if so, how did it come out?

I got the new fuel pump, but the basket was broken so they're shipping me a new one. It should be here on Wednesday, and I found another shop to actually do the work for me but I'm not on his schedule yet. He says I'm about two weeks out.

The short answer is not yet.

One of the members over at the other forum thinks he has the Forscan as builts figured out, but no one else has done a swap on a '21 yet so it hasn't been proven.

The only other member over there that has done a swap on a '21 used the wrong fuel pump and he can't get the DTE (distance to empty) to work right. It seems to be stuck on 999.

I don't know if I mentioned it here, but the cheapest place with shipping that I found the fuel pump was at Blue Springs Ford.

 

[Coacher]

No doubt the larger tank is nice on long road days. Also seeing 735 miles until empty is funny.

 

[rustyrider]

It’s all about going further between fill ups while towing the camper

 

[True North]

It’s all about going further between fill ups while towing the camper

New poster here and really interested in your conversion. I spent $450 and ordered the 36 gallon tank on my 21 but my truck`s fuel gauges are grossly inaccurate which doesn't allow using the option. Both the Ford Factory and dealership mechanic are clueless about what's causing the error and what to do. Reading your comments about the two different fuel pumps mirrors what I`m now being told by professional mechanics that the wrong pump was installed at the factory. I ended up with a lemon and am thoroughly disgusted with this truck and its problems, but its for sale and a new truck is being ordered shortly. It wont be a Ford. You seem to have good knowledge of what correct instrumentation is so I`m really looking forward to how you dial in the gauges and make everything read right. I can also pass that info on to a friend that has the exact same truck problem. Thanks for doing the work and posting about it. GLTA

 

[rustyrider]

New poster here and really interested in your conversion. I spent $450 and ordered the 36 gallon tank on my 21 but the my truck`s fuel gauges are grossly inaccurate which doesn't allow using the option. Both the Ford Factory and dealership mechanic are clueless about what's causing the error and what to do. Reading your comments about the two different fuel pumps mirrors what I`m now being told by professional mechanics that the wrong pump was installed at the factory. I ended up with a lemon and am thoroughly disgusted with this truck and its problems, but its for sale and a new truck is being ordered shortly. It wont be a Ford. You seem to have good knowledge of what correct instrumentation is so I`m really looking forward to how you dial in the gauges and make everything read right. I can also pass that info on to a friend that has the exact same truck problem. Thanks for doing the work and posting about it. GLTA

I'm a ford guy from way back, and I hate to hear you've had so many problems. Also I hope you didn't get the wrong idea about my experience or expertise. I'm not any kind of software expert that has a handle on the Forscan stuff. I will hopefully be able to follow the instructions that others have been working on, but it's still somewhat trial and error with the Forscan as builts. I in no way have anything to do with figuring that stuff out.

From your post however, it seems that the wrong fuel pump could have been installed, especially if the gauge and distance to empty are so far off.

 

[True North]

I'm a ford guy from way back, and I hate to hear you've had so many problems. Also I hope you didn't get the wrong idea about my experience or expertise. I'm not any kind of software expert that has a handle on the Forscan stuff. I will hopefully be able to follow the instructions that others have been working on, but it's still somewhat trial and error with the Forscan as builts. I in no way have anything to do with figuring that stuff out.

From your post however, it seems that the wrong fuel pump could have been installed, especially if the gauge and distance to empty are so far off.

I go back a ways with Ford vehicles also. Over 50 years. This is at least my tenth Ford pickup, plus two Dodge Cummins diesels, two Rangers, a Bronco, F-600 stake bed, a Silverado, Colorado and some cars thrown in for good seasoning. No stranger to trucks. My 2021 f150 is simply the worst vehicle I`ve ever owned. All this aside, my point with your gas tank conversion is that you`re taking on some knarly stuff that even a Ford mechanic and at least one Ford factory engineer doesn't understand. Take your time and be safe. If something was to go wrong it probably wouldn't be good. Thanks again for sharing your project with us.

 

[rustyrider]

I go back a ways with Ford vehicles also. Over 50 years. This is at least my tenth Ford pickup, plus two Dodge Cummins diesels, two Rangers, a Bronco, F-600 stake bed, a Silverado, Colorado and some cars thrown in for good seasoning. No stranger to trucks. My 2021 f150 is simply the worst vehicle I`ve ever owned. All this aside, my point with your gas tank conversion is that you`re taking on some knarly stuff that even a Ford mechanic and at least one Ford factory engineer doesn't understand. Take your time and be safe. If something was to go wrong it probably wouldn't be good. Thanks again for sharing your project with us.

I get it.

I have some trepidation about it, to be honest. I may yet wait a while and let someone else be the guinea pig. Everything is working well right now and hope to keep it that way....even my trailer brake finally seems to be working right, lol.

 

[rustyrider]

Fuel tank swap completed this morning. I have a total of $717 in the swap.

tank $150
fuel pump $267
labor $300

I haven't ventured into Forscan yet to make the adjustments for the miles to empty to read correctly, but the mpg's and fuel level gauge all look normal.

It might be more money than some are willing to spend, but I like the swap. For anyone contemplating this swap, the fuel pump for the extended range tank for the '21 F150's is a different part number from all other years.

I can confirm that a tank from '15 and up trucks will work for this swap in a '21.

edit: this is a 5.0l truck

 

[DUDE]

Fuel tank swap completed this morning. I have a total of $717 in the swap.

tank $150
fuel pump $267
labor $300

I haven't ventured into Forscan yet to make the adjustments for the miles to empty to read correctly, but the mpg's and fuel level gauge all look normal.

It might be more money than some are willing to spend, but I like the swap. For anyone contemplating this swap, the fuel pump for the extended range tank for the '21 F150's is a different part number from all other years.

I can confirm that a tank from '15 and up trucks will work for this swap in a '21.

edit: this is a 5.0l truck

THANKS FOR POSTING YOUR RESULTS!

 

[Billy231]

Not sure if you have searched other brands of aftermarket replacement tanks. I have a 2021 F150 3.0 Diesel, mandatory 26 gallon tank only. Titan makes an aftermarket tank of 40 gallons for the 5.5" bed and a 48 gallon tank for the 6.5" bed. They are available now for $1100-1200. Supposedly an "easy swap"!
I am considering one myself. Just a thought for you, check them out.

 

[rustyrider]

Not sure if you have searched other brands of aftermarket replacement tanks. I have a 2021 F150 3.0 Diesel, mandatory 26 gallon tank only. Titan makes an aftermarket tank of 40 gallons for the 5.5" bed and a 48 gallon tank for the 6.5" bed. They are available now for $1100-1200. Supposedly an "easy swap"!
I am considering one myself. Just a thought for you, check them out.

The Titan fuel tank you've referenced is only for diesel engines, unfortunately.

 

[rustyrider]

It appears I may have gotten the DTE readings corrected. Here's a link for anyone interested.

https://www.f150forum.com/f129/fuel-tank-swap-forscan-adjustments-511630/#post7063148

 

[Kentucky Leadfoot]

Thank you @rustyrider for your writeup...gave me the courage to try this myself...

$175 Tank
$300 Fuel Pump
$170 Fuel filler hose assembly

Hardest part(as noted in most threads/vids) were removing the plastic clips(red and blue) on the vent tubes connecting to fuel pump - which I damaged when trying to disassemble due to limited space/access...

Blue plasic clip on the filler hose vent tube is not sold by itself, hence I had to buy the fuel filler hose assembly

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