re-calibrating the fuel level sensor {F0101}

[LB72004]

for anyone wanting to re-calibrate the fuel level sensor on the 26 gal tanks these are the numbers that that i came up with:
Gallons Voltage

0 gal 0.686275
1 gal 0.764706
2 gal 0.901961
3 gal 1.019608
4 gal 1.137255
5 gal 1.254902
6 gal 1.352941
7 gal 1.450980
8 gal 1.509804
9 gal 1.588235
10 gal 1.686275
11 gal 1.764706
12 gal 1.803922
13 gal 1.882353
14 gal 1.941176
15 gal 2.019608
16 gal 2.078431
17 gal 2.156863
18 gal 2.215686
19 gal 2.274510
20 gal 2.313725
21 gal 2.397205
22 gal 2.470588
23 gal 2.529412
24 gal 2.529412
25 gal 2.529412
26 gal 2.529412
27 gal 2.529412

i did this by removing my bed, pulling the pickup unit and sucking the remaining fuel out till dry. i then reassembled everything and while running the scan tool and monitoring fuel level sensor voltage i added one gallon of fuel at a time and took note of the voltage.

i then entered the data into my tune and crossed my fingers. well it tracks nicely, almost exactly nuts on in relation to the odometer.

this is what my {F0101} table looks like now (photo). i did not try to smooth the cells as the ECM/BCM does this already to the the gauge. the gauge still sits on full for the first couple of gallons as the sensor maxes out but there is still room for more.

i have also attached a text file with all the figures for anyone who wants to copy & paste them into their tune

[Wheelz]

Thanks!

[Boost]

Thanks for the great work, much appreciated!

[cmitchell17]

im going to try this thanks a lot.

[hecatti]

thank you very much!!

[anthonyshaw]

I just tried to use your values in my EFILive for my 08 LMM and I'm showing a table of volts and allows me to enter the value (in gallons) of fuel for that voltage (ends up backwards from your table) what version of EFI Live did you use to create this table?

[LB72004]

version is irrelevant for this. the problem is that in the later years, LBZ??? they used a different fuel level sensor that reads backwards and the scale is changed too. the figures i gathered would only work on the LB7 and LLY fuel level sensors.

you could swap out the pickup/sensor and use the figures but at that time you may as well log your own by then

is yours a 26 gal or 34 gal tank? i am planing on rescaling my 08 LMM 34 gal tank here shortly so the fuel light doesn't come on with 19 gallons left in the tank:bash:

[anthonyshaw]

Didn't even realize you had an LB7 in your signature as well, saw the 08 and got very excited :)

I only have a 26 gal tank. I have thought about re-scaling from empty (not quite as far as you went) but reading at ~20gal used and adding a gallon and making the reads from there and matching as closely as I can. My gauge reads empty at about 12-13 gallons used.

Thanks for the reply.


version is irrelevant for this. the problem is that in the later years, LBZ??? they used a different fuel level sensor that reads backwards and the scale is changed too. the figures i gathered would only work on the LB7 and LLY fuel level sensors.

you could swap out the pickup/sensor and use the figures but at that time you may as well log your own by then

is yours a 26 gal or 34 gal tank? i am planing on rescaling my 08 LMM 34 gal tank here shortly so the fuel light doesn't come on with 19 gallons left in the tank:bash:

[LB72004]

:thumb_yello:

[DURAtotheMAX]

version is irrelevant for this. the problem is that in the later years, LBZ??? they used a different fuel level sensor that reads backwards and the scale is changed too. the figures i gathered would only work on the LB7 and LLY fuel level sensors.

you could swap out the pickup/sensor and use the figures but at that time you may as well log your own by then

is yours a 26 gal or 34 gal tank? i am planing on rescaling my 08 LMM 34 gal tank here shortly so the fuel light doesn't come on with 19 gallons left in the tank:bash:

Actually it was 2004.5 when they changed fuel level sensors.

2001-2004 LB7 is the one that reads backwards. 2004.5-2015+ reads "proper". :)

Ben

[LB72004]

yep, your right. just checked an LLY tune and sure enough it is "forward"

so the above logged figures only applies to 26 gallon LB7 (maybe gas rigs too) trucks

[LB72004]

just logged voltage per gallon on the 34 gallon tank in my LMM.

now, trying to input the values in the tune and having major issues. whoever decided on the values to use for volts in the tune at GM should be shot. why would the values drop from 5.0 volts to 2.502 volts then more reasonably from there. there is a whole lot of range between those values that is needed for accurately rescaling the gauge. well i am going to try putting some of the logged values into the tune and see what it does. just wish it was more like the LB7. that one has more values than needed.

anyone, Hint, Hint: Ross, Paul, Cindy, know if those voltage values in {F0101} can be changed to something more usable?

[anthonyshaw]

just logged voltage per gallon on the 34 gallon tank in my LMM.

now, trying to input the values in the tune and having major issues. whoever decided on the values to use for volts in the tune at GM should be shot. why would the values drop from 5.0 volts to 2.502 volts then more reasonably from there. there is a whole lot of range between those values that is needed for accurately rescaling the gauge. well i am going to try putting some of the logged values into the tune and see what it does. just wish it was more like the LB7. that one has more values than needed.

anyone, Hint, Hint: Ross, Paul, Cindy, know if those voltage values in {F0101} can be changed to something more usable?

I wondered about that jump in the F0101 table when I was looking at it, myself. I haven't done anything with mine since I tried to update firmware last week and bricked my FlashScan... hopefully someone gets back and gives some answers on this.

[LB72004]

Well, not being able to get my gauge working properly and running out of fuel before the light came on i decided to replace the sender.

this is what i used: http://www.ebay.com/itm/Auto-Meter-3262-Universal-Fuel-Level-Sender-2-1-16-in-And-2-5-8-in-/291262978015?hash=item43d0a057df&vxp=mtr

it has the needed 30-240 ohm range. i set it up in the tank last night so that it at empty it is at 1.9 volts and at full it is 0.7 volts. this allows my to avoid the stupid GM calibration section in F0101 and get a smooth drop all the way to E. i know i will have less figures to work with but i dont think that will be a problem. now i just need to run the tank dry and do the one gallon at a time fill/logging

i dont think my logged data will be of any value to any of you unless you also install the Auto Meter 3262 and set it up like mine

anyways, i will let you know how it works out

[jevs]

Did anyone ever chart their voltages on the large tank LMM? I need to know what to expect for a 2008 Silverado Duramax CCLB. I am only getting down to 1.137 Volts at a full tank. Before I get in there and bend the float arm I would like to know what other people are getting :)
It would be nice if the float dropped lower to get rid of the reporting empty with 10+ gallons left. The float needs to drop closer to the bottom in my opinion which would also push the sensor higher and get to a lower voltage on the full end. These things seem to be all over the place from reading posts on the net. The universal theme is that they all report empty way too soon. Knowing the voltages on a good working truck that is to OEM specs would be helpful. I am not sure if I need a mechanical fix or just a tune adjustment. The voltages won't change regardless of the tune, so that is better than a percentage calculated.
I know the full can be fixed easily, but that won't do anything for when the float gets to the bottom and cannot drop any further. It is still about 3/4" from the bottom when the tank is dry. I did not measure it when I should have putting the sump in, but the float was right there so I could see it. I don't know if this is where it normally stops.
Mine is only going to 88% at full when topped all the way to the fuel cap. I am waiting for the tuner to set it for the large tank instead of the small tank. He says this will fix it, but that would mean the full voltage on the small tank vs the big tank is different. Not sure... I am not sure if the full voltage changes between the two tank sizes. Unfortunately I am using locked tunes and cannot change anything even though I have everything to do it :(

[ksieckmann]

Boo hoo ;)

[jevs]

Boo hoo ;)

Haha. I guess we will know more tommorow night.. got your email. I will let you know what it does after that and pester you some more :)
Unfortunately I still suspect a sending unit change or adjusting the float in my future.

[LB72004]

i have the stock charted values (unbent float arm:D) somewhere, i'll see if i can find them for you.

it is highly likely that my sensor was not working right. if i recall correctly, i was only able to see about 1/2~3/4 of the voltage range available. also, my float did go all the way to the top of the tank, or close to it, and all the way down to the bottom. i thought about bending the arm too, but if i am not mistaken, it would have prevented the float from reaching the top of the tank or reading full for a very long time. the only way i saw making it work was to extend the arm longer, thus changing it out for an aftermarket sensor

[jevs]

Yeah. I may be in for a new sending unit. But I am going to load the tune with the proper size tank and the go from there. I have not looked at the shape of the arm vs. tank to see what bend might work. If you can bend the float down in a way that the float can still go all the way to the top without the wire hitting the top of the tank first, then it will be at a higher position at the sending unit and therefore at the desired lower voltage and drop lower on the tank to help with the low fuel report when there is lots of fuel left. The voltage at the empty side will not change as long as the float does not actually bottom out on the tank. There is plenty of room to go down without that happening. They set these things pretty high off the bottom if my truck is a typical setup.