how is fuel tank level calculated?

[NWhunt]

Installed the Titan 50 gallon fuel tank with a Fleece lift pump. I am interested to see how the gauge reads now with the new lift pump.

I’m thinking of doing this on my 2500 but am nervous about the inaccuracy of the gauge afterward. Let us know how it reads after you test it out.


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[PauleyB2112]

I just noticed the same thing on my truck. 2020 1500 Bighorn with 33 gal tank. I drove it for two days (total about 50 miles) after the low fuel light came on and I let the gauge go to zero. It only took 24 gallons to fill it. I have a non related service appointment tomorrow so I'll ask them to check it while I am there. I'll report back if there is anything of note.

 

[CMil527]

Same here.. first fill up on my rig with 33 gallon tank low fuel light on only took 26.2 gallons. Glad to see they got this resolved since my 2015 did the same thing. Annoying!!

 

[JeffN]

installed a Titan tank with a Fleece lift pump. First refuel yesterday, with the low fuel light on and 31 miles of range remaining, the tank took 42 gallons. 8 gallons were in it with 31 miles of range. I drove 550 miles before refueling.

The math says that I’d get 660 miles on a tank of fuel, running light. It is interesting to me the relationship between the computer and the tank sensor in these trucks. With two different pumps and sensors in two different tanks, the gauge is still wanting me to fill up with a good amount of fuel remaining.

 

[18CrewDually]

Theres a few threads on this matter which I have posted on about using AlphaOBD app to recalibrate the CLUSTER readings of the gauge to coincide with actual fuel level.
Like others my fuel light would come on @ 50 mile range. When I would fill it would only take 26. At most it took 29 and that was with the gauge on E hard for 25+ miles. My 2018 CTDHO truck has the 32 gal tank.

So I went into the Body module using ALPHAOBD and changed some settings. One thing was the capacity to 121 liters (32 g) . I also changed the Cluster Calibration percentage readings for FULL, LFW, & EMPTY to the highest for full, and lowest for empty and the LFW I think I set to 2 or 5%.

I ran a test initially after the recal. I filled the tank and ran it down to 1/4 tank on the gauge. Upon filling, from 1/4 to half it took 8.2 gallons. I continued to fill to half and it took another 8 gallons. The to full it took another 8. Since it's a 32 gallon tank it looked pretty promising my gauge is accurate.

Final test I ran it empty yesterday. the 50 mile range light came on with the needle in the red. I continued to run it until the needle was down to E and range wouldn't give miles anymore. I filled the tank yesterday morning and sure enough the pump clicked off at 31.7 gallons with me able to top it off with 32.2 gallons. I don't normally top off but I wanted to see how much more I could squeeze in.

Conclusion problem solved for me. I'm going to run this tank low again and see if it has the same results.

 

[Over The Hill]

Sounds like the upgrade to 33 gal tank is just the tank. All calibrations may be for the 26 gal tank. Just thinking out loud.
I too have 33 gallon tank. I always fill up when gauge gets just under 1/2. Maybe I'll go longer and see what my gauge is reading. Only have 1200 miles on it and really haven't given it any thought.

 

[tourrider]

Theres a few threads on this matter which I have posted on about using AlphaOBD app to recalibrate the CLUSTER readings of the gauge to coincide with actual fuel level.
Like others my fuel light would come on @ 50 mile range. When I would fill it would only take 26. At most it took 29 and that was with the gauge on E hard for 25+ miles. My 2018 CTDHO truck has the 32 gal tank.

So I went into the Body module using ALPHAOBD and changed some settings. One thing was the capacity to 121 liters (32 g) . I also changed the Cluster Calibration percentage readings for FULL, LFW, & EMPTY to the highest for full, and lowest for empty and the LFW I think I set to 2 or 5%.

I ran a test initially after the recal. I filled the tank and ran it down to 1/4 tank on the gauge. Upon filling, from 1/4 to half it took 8.2 gallons. I continued to fill to half and it took another 8 gallons. The to full it took another 8. Since it's a 32 gallon tank it looked pretty promising my gauge is accurate.

Final test I ran it empty yesterday. the 50 mile range light came on with the needle in the red. I continued to run it until the needle was down to E and range wouldn't give miles anymore. I filled the tank yesterday morning and sure enough the pump clicked off at 31.7 gallons with me able to top it off with 32.2 gallons. I don't normally top off but I wanted to see how much more I could squeeze in.

Conclusion problem solved for me. I'm going to run this tank low again and see if it has the same results.

View attachment 234440

I need to do this. My 3500 SRW does the same thing. So tired of towing my 5th wheel and light comes on at 260 miles.


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[Over The Hill]

Just topped off. Gauge was down half way into red. Never got a warning for low fuel. 33 gal tank took 29.5 gallons. 3.5 gallons remaining. Close enough for me.