LLY: 52 Gal SuperTank Fuel Level Sensor Scaling

raceghost

Animal
Sep 28, 2018
92
0
0
Out West
Well, that didn't go as planned...lol. Driven around the last 2 days on E with Light on, figured I maybe had 5 gallons in the tank when I pulled onto the 4 post alignment rack to do my work....

As to try not to make a mess, we used the air jacks to lift the rear of the truck in the air to get the fuel to the front of the long tank forward, so when I cut the sump line at the bottom, wouldn't spill diesel everywhere...

Cut the line on the Sump, and diesel started running, grabbed the first 6 gallon can with funnel as diesel ran all down my arms and started the catch process. Fuel wasn't running wild, but constant flow, though it seemed rather like much wasn't in there... Then realized truck ass was still in the air, and gas cap still on... Here came the fun...

Opened the gas cap, and what was small flow became rushing flow, filled the first 6 gallon can with ease... Grabbed the second and lowered the ass end. Filled the second can with ease as well... Oh shit, grabbed a 5 gallon bucket, filled it about half, and then set it on the floor for finally it seemed we were at the bottom... Dripped for 25 minutes, and the 5 gallon bucket was now 2/3 full... So I had roughly 13.5 gallons once we got an accurate count of what was actually in the cans... Driving on E with light on for 2 days mind you.

After all of this, my buddy, changing my lift pump filters was like, "I don't know why you just didnt pump it out with the lift pump...?" As I banged my head against the lift...SMH..DOH.

So here we go, the calibration of a 52 Gallon official Super Tank which is a 52 gallon tank, with roughly 48 Gallon usable with sending unit, or 52 gallons if you sump it. Mine is sumped, only utilizing the sending unit for the fuel level sensor, and later to plumb in an auxiliary tank, and utilize the fuel straw as the plumb in for gravity fed bed tank.

Step 1:
Empty fuel cell

Step 2:
EFI Live v7.5 Scan software, make sure the Fuel Level voltage is checked to log, and start your log.
Note: Most likely it will say 5V on your LLY if you did the conversion like I did(read Sig on Sending unit) for it requires an LB7 sending unit for this tank, but I made a franken-sending unit.

Step 3: Now that your logging and you have 5v for LLY or 0V for LB7, add 5 gallons of diesel. This should at least get you going, and start to change those voltages.
Note: You might experience some flashing between 5V or 0V respectively, for the fuel needs to calm down and not wave or surge in the tank, so be patient on this step. Also, because of how the stock map is scaled, the first voltage reading to get steady is a little tricky, for the scaling says its empty at 2.5V or so on the LLY, and sits there and wants to go to 5V all the time. However, reset your log data so that nothing is showing then start the log again, this time watch the Min field in the log on the Voltage and watch it change. After a minute or two, it will calm down, and the actual reading will appear. Mine didn't move with 5 gallons. SO I added 2 more Gallons to bring the total up to 7 gallons. Finally I got a reading. My LLY Sending Unit Voltage read 3.5V. My first and highest voltage change after adding fuel, make sure you notate the first voltage change and what it is, as well as how much fuel was there when it finally changed, you will need this data later.

Step 4: Drive to Nearest Gas station of your choice, and play the 2 gallon game, and log those voltages.
Note: the more precise you can be in the logging of every 2 gallons will pay off in the end.

Here are my voltages:
3.5V ~ 7 Gallons
3.0V ~10 Gallons
2.5V ~13 Gallons, also Quarter of tank
2.4V ~15 Gallons
2.4V ~17 Gallons
2.3V ~19 Gallons
2.3V ~20 Gallons
2.2V ~22 Gallons
2.1V ~24 Gallons
2.1V ~26 Gallons, also Half a tank
2.0V~ 30 Gallons
1.8V~ 35 Gallons
1.6V~ 39 Gallons, ALso 3/4 Full Tank
And I was out of money...lol. $90 for 26 Gallons of Diesel...
Note: The reason you want to be precise expecially with gallons relating to 1/4, 1/2, and 3/4 of a tank respectively, by the voltage, and Gallon, not the gauge... Is it will make the Map smoothing with the EFI Live software for the Fuel Level Sensor Primary voltage vs. Gallons table.

Step 5: Drive home and edit your tables:

F0301(Main Fuel Tank Size),
This is the physical size of your tank, in our case 52.00

F0302(Main Fuel Tank Size Full),
This is the usable gallons of your tank when it is full, in our case, 48.08 if using sending unit, 50.00 if sumped.

F0303(Combined Fuel Tank Capacity),
Set the same as table F0301 unless you have two tanks, auxiliary tanks with no sending unit utilizing this table will be discussed at a later date. Most likely it wont work, but its a thought, look for another thread on this subject when it arrives.

Note: I am certain one of F0301~F0303 tables is used in conjunction with the DIC calculations on fuel used and gallons used, but dont have any hard data on which one it is, my bet is on the F0302 table...

F0101(Fuel Level Sensor Primary) tables.
The Left column is voltage, the right column is gallons.

Note: When entering your gallons on the right, find the voltages that correlate in your data, to 1/4, 1/2, and 3/4 tank first. This will help in smoothing later if your voltages seem weird. Then for all voltages you logged, enter them into their respective cells. You might notice like mine, some gallons registered the same voltages. So since the logging software only goes to the 10th of a volt, and not the mV, I erred on the low end where I could. I.E. with 24 and 26 gallons in my data registered 2.1V I used 2.18 volts as 24 gallons, and 2.10V as 26 gallons. I hope that makes sense. Either way in the end, you will utilize the smoothing feature within the software to make it finalized once voltages vs gallons are all entered.
Also, with reserves, since my voltage didn't change from 5V till I had 7 gallons in and then read 3.5V, I set the 3.5V at 7, and every voltage after that 0. This means once the light comes on, I have 7 gallons in reserve, I suggest you do the same with at least 5 gallons at your lowest/highest readable voltage respectively depending on your sending unit.
Second note: Understanding why some areas voltage readings dont change with accuracy of fuel filled. Well, think about the ARC motion of the Fuel Level arm. Its range is roughly 70 degrees of movement. You will find more accuracy or change in volts in the middle or half of a tank, and you will find less towards empty and towards full. When the fuel level arm is in middle of the tank, it is horizontally out, and moves greater distance up and down than when it is angled towards the top, and angled at the bottom respectively of the fuel cell.

Here are my Voltages/Gallons:
0 52
0.02 52
0.04 52
0.06 52
0.08 52
0.1 52
0.12 52
0.14 52
0.16 52
0.18 52
0.2 52
0.22 52
0.24 52
0.26 51.95
0.28 51.9
0.3 51.85
0.32 51.8
0.34 51.75
0.36 51.7
0.38 51.65
0.4 51.6
0.42 51.55
0.44 51.5
0.46 51.45
0.48 51.35
0.5 51.25
0.52 51.15
0.54 51.05
0.56 50.95
0.58 50.85
0.6 50.75
0.62 50.65
0.64 50.55
0.66 50.45
0.68 50.35
0.7 50.25
0.72 50.15
0.74 50.05
0.76 49.95
0.78 49.89
0.8 49.78
0.82 49.68
0.84 49.57
0.86 49.47
0.88 49.36
0.9 49.25
0.92 49.15
0.94 49.04
0.96 48.94
0.98 48.83
1 48.73
1.02 48.63
1.04 48.52
1.06 48.41
1.08 48.31
1.1 48.2
1.12 48.1
1.14 47.99
1.16 47.69
1.18 47.39
1.2 47
1.22 46.6
1.24 46.2
1.26 45.8
1.28 45.4
1.3 45
1.32 44.6
1.34 44.2
1.36 43.8
1.38 43.4
1.4 43
1.42 42.6
1.44 42.2
1.46 41.8
1.48 41.4
1.5 41
1.52 40.6
1.54 40.2
1.56 39.8
1.58 39.4
1.6 39
1.62 38.6
1.64 38.2
1.66 37.8
1.68 37.4
1.7 37
1.72 36.6
1.74 36.2
1.76 35.8
1.78 35.4
1.8 35
1.82 34.5
1.84 34
1.86 33.5
1.88 33
1.9 32.5
1.92 32
1.94 31.5
1.96 31
1.98 30.5
2 30
2.02 29.2
2.04 28.4
2.06 27.6
2.08 26.8
2.1 26
2.12 25.2
2.14 24.4
2.16 23.6
2.18 22.8
2.2 22
2.22 21.6
2.24 21.2
2.26 20.8
2.28 20.4
2.3 20
2.32 19
2.34 18
2.36 17
2.38 16
2.4 15
2.42 14.6
2.44 14.2
2.46 13.8
2.48 13.4
2.5 13
2.52 12.88
2.54 12.76
2.56 12.64
2.58 12.52
2.6 12.4
2.62 12.28
2.64 12.16
2.66 12.04
2.68 11.92
2.7 11.8
2.72 11.68
2.74 11.56
2.76 11.44
2.78 11.32
2.8 11.2
2.82 11.08
2.84 10.96
2.86 10.84
2.88 10.72
2.9 10.6
2.92 10.48
2.94 10.36
2.96 10.24
2.98 10.12
3 10
3.02 9.88
3.04 9.76
3.06 9.64
3.08 9.52
3.1 9.4
3.12 9.28
3.14 9.16
3.16 9.04
3.18 8.92
3.2 8.8
3.22 8.68
3.24 8.56
3.26 8.44
3.28 8.32
3.3 8.2
3.32 8.08
3.34 7.96
3.36 7.84
3.38 7.72
3.4 7.6
3.42 7.48
3.44 7.36
3.46 7.24
3.48 7.12
3.5 7
3.52 0
3.54 0
3.56 0
3.58 0
3.6 0
3.62 0
3.64 0
3.66 0
3.68 0
3.7 0
3.72 0
3.74 0
3.76 0
3.78 0
3.8 0
3.82 0
3.84 0
3.86 0
3.88 0
3.9 0
3.92 0
3.94 0
3.96 0
3.98 0
4 0
4.02 0
4.04 0
4.06 0
4.08 0
4.1 0
4.12 0
4.14 0
4.16 0
4.18 0
4.2 0
4.22 0
4.24 0
4.26 0
4.28 0
4.3 0
4.32 0
4.34 0
4.36 0
4.38 0
4.4 0
4.42 0
4.44 0
4.46 0
4.48 0
4.5 0
4.52 0
4.54 0
4.56 0
4.58 0
4.6 0
4.62 0
4.64 0
4.66 0
4.68 0
4.7 0
4.72 0
4.74 0
4.76 0
4.78 0
4.8 0
4.82 0
4.84 0
4.86 0
4.88 0
4.9 0
4.92 0
4.94 0
4.96 0
4.98 0
5 0
5.02 0
5.04 0
5.06 0
5.08 0
5.1 0
5.12 0

Step 6: Save your work, flash to truck, and test the settings. Especially test the settings once the fuel tank gets low, not the light on, but low towards E, and read your voltage to see if the reserve compensation you gave it is actually there.

I attached an text document with settings for the LLY if those of you wish to be lazy and take my word for it...
Also, here is a pic of my new scaled table F0101

Hope this helps with anyone doing a larger tank install, or just simply rescaling there tank so the gauge actually reads better.

Cheers,
 

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Last edited:

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
18,199
438
83
Phoenix Az
Very nice Race. there have been quite a few people this has plagued. Made as a sticky cause its good info.
 

Burn Down

Hotrodder
Sep 14, 2008
7,064
2
38
Boise Idaho
Nice, I’ll compare it to the 05’ as it has a 50 gallon tank as well. The guy I bought the truck from said it will go a ways with light on, guessing it’s off a touch.
 

raceghost

Animal
Sep 28, 2018
92
0
0
Out West
Thanks guys, just trying to contribute. I think it will work for most fuel cells, and I am looking to add that auxiliary bed tank, and feed it through my sending unit since my 52 is sumped. Will do some more additions on that later when I get there. Now I am just trying to figure out basic tuning of the diesel and understand the tables.

Cheers,
 

Burn Down

Hotrodder
Sep 14, 2008
7,064
2
38
Boise Idaho
I need to double ck but it’s not looking to be correct for a 50 gallon Aero tank:rofl: I just ran out in the busiest intersection in Boise, I did suspect it was off and luckily had thrown 5 gallons in the bed. I’ll ck and post back.
 

Burn Down

Hotrodder
Sep 14, 2008
7,064
2
38
Boise Idaho
I was just telling a guy at work it was making me nervous. I was going in early to drain what was left so I would know for sure... whoops:eek:
 

raceghost

Animal
Sep 28, 2018
92
0
0
Out West
I need to update. I found an error in the way you account for the reserve. Also, due to these tanks not having baffles, when they get down to about 10 gallons, they surge very badly when you accelerate and slow down sharply. I have done many tests since my initial post and have some updates.

Also, is yours sumped or utilizing the sending unit. The sending units are worse...

IF a moderator will give me access to update the post with a couple new changes and tested findings. I would greatly appreciate it. Not much will change, but I will update the reserve voltages and findings. I would like to ad edits to the original post.
 

JoshH

Daggum farm truck
Staff member
Vendor/Sponsor
Feb 14, 2007
13,203
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Texas!!!
I need to update. I found an error in the way you account for the reserve. Also, due to these tanks not having baffles, when they get down to about 10 gallons, they surge very badly when you accelerate and slow down sharply. I have done many tests since my initial post and have some updates.

Also, is yours sumped or utilizing the sending unit. The sending units are worse...

IF a moderator will give me access to update the post with a couple new changes and tested findings. I would greatly appreciate it. Not much will change, but I will update the reserve voltages and findings. I would like to ad edits to the original post.
Post your edits in a new post, and I will copy/paste it into the original.
 

IdahoRob

New member
Jun 5, 2007
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Or you can just adjust the % of increase of the new tank size to the existing stock scaling in the fuel sensor primary table. So going from a 26 gallon stock tank to a 52 gallon tank, add 110%. This has worked for many years and have never heard any complaints as it keeps the stock scaling graph.
 

raceghost

Animal
Sep 28, 2018
92
0
0
Out West
Or you can just adjust the % of increase of the new tank size to the existing stock scaling in the fuel sensor primary table. So going from a 26 gallon stock tank to a 52 gallon tank, add 110%. This has worked for many years and have never heard any complaints as it keeps the stock scaling graph.
Interesting, thanks Rob.
 

raceghost

Animal
Sep 28, 2018
92
0
0
Out West
Or you can just adjust the % of increase of the new tank size to the existing stock scaling in the fuel sensor primary table. So going from a 26 gallon stock tank to a 52 gallon tank, add 110%. This has worked for many years and have never heard any complaints as it keeps the stock scaling graph.
Rob, I actually did do that first, but then found that there was still about 13 gallons left in the tank when the light came on, thats why I decided to actually do it the way I described in this writeup.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
18,199
438
83
Phoenix Az
Rob, I actually did do that first, but then found that there was still about 13 gallons left in the tank when the light came on, thats why I decided to actually do it the way I described in this writeup.
whats the scaling difference between the 110% way and the "fill,check" method? you should be able to compare cal/alt tunes table to table as long as the OS is the same between the two tunes. makes it easy to see the difference
 

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