how is fuel tank level calculated?

[TestPilot57]

Thirty minutes of time is cheap insurance against being stranded in a traffic jam or storm with an empty tank.

I guess it also depends on where you live. Around here a "traffic jam" might cost you 5 minutes. Maybe 10 minutes once or twice in my life? And in those cases, I shut the vehicle off, fuel status notwithstanding... In these parts if you have to wait 30 seconds to pull into traffic, or at an intersection (we don't have traffic lights in our town - there are 4 sets of traffic lights in about a 30 mile radius) you start seeing red.

And I do occasionally fill my tank when it's half or above, like if I'm going on a trip, or if I'm on a trip and see a sign that says "Next gas 400 miles".

 

[TestPilot57]

Yup this took a left turn.

Without frankenthreading even this forum would quickly become too dull for most (based on observation).

 

[Narg]

My last Silverado did a very similar thing to me once. Came out and was on "E" with warnings. Still had 1/2 a tank. Never saw it again after that. I guess things just get sticky sometimes.

 

[mikeru]

Probably going to hammered for this, but I never understood the concept of waiting until the low fuel light or x miles to empty before filling up. I taught my kids that it doesn’t cost any more to keep the top half of the tank full than the bottom half. Empty tanks draw condensation and worrying about gas if you get caught in traffic, a bad storm or any other unfortunate event is virtually eliminated.

Not saying I’ve never seen my gauge below half, but it is rare that I do and it’s never for very long.

I agree with you for the most part. I'd much rather run on the top half of the tank, so I usually fill up before it gets to 1/4 tank remaining. I do disagree with one thing you said though, and that's the part about empty tanks drawing condensation. That was true when fuel tanks were made of metal. But the plastic tanks modern vehicles use now aren't prone to that problem.

feel free to debate the merits of refueling frequency, I’m just trying to figure out why my truck was telling me I was empty and not even computing range when I had 9 gallons of fuel still in the tank. I looked up my VIN and Ram is telling me there are no updates but it sounds like other owners have had this problem. I guess I’ll have to go to the dealer and have them tell me there is nothing wrong with my truck.

It's been my experience with Ram trucks that there seems to be about four gallons of fuel in the system on the rare occasion when I fill up after the low fuel light comes on. Those were all 1500's, and I haven't owned a HD Ram truck. But 9 gallons seems pretty significant. I'd probably check again at the next fill-up, and have it looked at if you see the same thing.

 

[Jimmy07]

It's been my experience with Ram trucks that there seems to be about four gallons of fuel in the system on the rare occasion when I fill up after the low fuel light comes on. Those were all 1500's, and I haven't owned a HD Ram truck. But 9 gallons seems pretty significant. I'd probably check again at the next fill-up, and have it looked at if you see the same thing.

Just to clarify/compare what issue some of us are having with 31/32 gallon tanks- when the low fuel light first comes on (the indicator with the picture of a fuel pump), my range is normally ~40 miles. With my 31 gallon tank, if I was to pull over and fuel up at this point, I would only get 23 gallons pumped to fill up the tank. In the same situation with a 1500 with 26 gallon tank, it would also take 23 gallons.
If I continue to drive with the low fuel indicator light on until the range says “low”, needle pegged past E, then fuel up, I will get about 25 gallons pumped in before the tank is full. This is about the same as what a 1500 with 26 gallon takes in the same situation. Once my range says “low”, I can continue driving for about 100 miles, depending on city or highway, until I run out of fuel.
It’s as if the BCM fuel level programming for some 31/32 gallon tank equipped trucks is the same as the 26 gallon tank equipped trucks.

For those giving their testimonies about how often they fill up, or never letting the tank go below 1/4, this isn’t about that. This is about an option that some people paid for to get extended fuel range, and don’t have the ability to monitor the last ~6 gallons as accurately as a 26 gallon tank equipped truck.

 

[Tim Garceau]

Boy, what did we do in the years before all of this screen technology telling us to wipe our own ass after taking a **** and not before?

FWIW 26 Gallon tank on mine has been run to shutoff, got about 30~miles when the DTE was gone and low fuel light on EVIC. The level arm senders have a tolerance, find out what it is.

 

[Jimmy07]

Boy, what did we do in the years before all of this screen technology telling us to wipe our own ass after taking a **** and not before?

Sure, we can go all the way back to the Model T, and how people survived driving those, but this isn’t what we’re talking about here.

 

[JeffN]

this is exactly why I asked the question about range calculation. My MPG can drop 30% with a heavy trailer, hell any trailer that increases wind resistance. I have been on/off the trailer a lot over the last couple of weeks and what I was wondering is if the computer was saying to the gas gauge “hey looks like we’re not going to have a lot of range, better hit the light and tell this yoyo to fill ‘er up!”. I blew right through “40 miles” of range to the dash telling me “LOW” in a matter of 2 miles.

If the light is triggered by actual fuel volume, then this is not likely. My hypothesis is that the tank volume remaining is computed based on what the range estimate is, and then the gauge updates to reflect accordingly.

Just to clarify/compare what issue some of us are having with 31/32 gallon tanks- when the low fuel light first comes on (the indicator with the picture of a fuel pump), my range is normally ~40 miles. With my 31 gallon tank, if I was to pull over and fuel up at this point, I would only get 23 gallons pumped to fill up the tank. In the same situation with a 1500 with 26 gallon tank, it would also take 23 gallons.
If I continue to drive with the low fuel indicator light on until the range says “low”, needle pegged past E, then fuel up, I will get about 25 gallons pumped in before the tank is full. This is about the same as what a 1500 with 26 gallon takes in the same situation. Once my range says “low”, I can continue driving for about 100 miles, depending on city or highway, until I run out of fuel.
It’s as if the BCM fuel level programming for some 31/32 gallon tank equipped trucks is the same as the 26 gallon tank equipped trucks.

For those giving their testimonies about how often they fill up, or never letting the tank go below 1/4, this isn’t about that. This is about an option that some people paid for to get extended fuel range, and don’t have the ability to monitor the last ~6 gallons as accurately as a 26 gallon tank equipped truck.

 

[mtwofeathers]

That was a problem on the 1500s with the larger tanks, but first I've heard of it on the hd trucks. On the 1500s the fix was just a software update. Wonder if something is set up wrong in the ecu.

Yep just like oil pressure gauges, one never goes low, and always stayed in the sade range, dodges idea of making a customer feel good.

 

[SOKY_RAM]

I guess it also depends on where you live. Around here a "traffic jam" might cost you 5 minutes. Maybe 10 minutes once or twice in my life? And in those cases, I shut the vehicle off, fuel status notwithstanding... In these parts if you have to wait 30 seconds to pull into traffic, or at an intersection (we don't have traffic lights in our town - there are 4 sets of traffic lights in about a 30 mile radius) you start seeing red.

And I do occasionally fill my tank when it's half or above, like if I'm going on a trip, or if I'm on a trip and see a sign that says "Next gas 400 miles".

This

There are no traffic lights in the entire county that I live in. If I get caught in trafffic its either a wreck or a tractor. I rarely ever fill up until im on E, and its usually at the same station and pump. I can see if you lived in a big city that this might need some more consideration but my habits have worked for me the last 22 years.

 

[MikeDee]

I've been wondering about this. My window sticker for my new to me 1500 says 5 extra gallons of fuel. Does that mean I have a 31 gallon tank? I've gone down to the low fuel light but it only took maybe 23ish gallons? I don't remember exactly.

 

[Booms]

This thread went south in a HOT second.

F.W.I.W., my 2015 has a 3-4 gallon cushion it seems. 9 gallons is alot.

 

[mikeru]

I've been wondering about this. My window sticker for my new to me 1500 says 5 extra gallons of fuel. Does that mean I have a 31 gallon tank? I've gone down to the low fuel light but it only took maybe 23ish gallons? I don't remember exactly.

No, that means they put 5 gallons of fuel in your truck at the factory.

 

[mikeru]

For those giving their testimonies about how often they fill up, or never letting the tank go below 1/4, this isn’t about that. This is about an option that some people paid for to get extended fuel range, and don’t have the ability to monitor the last ~6 gallons as accurately as a 26 gallon tank equipped truck.

I get that you're trying to keep this thread on track, but the OP himself encouraged people to discuss how often they fill up in post #19.

FWIW, the OP didn't ask anything relating to the larger fuel tank option. He specifically asked how the fuel gauge reads the fuel level. He mentioned he has the larger fuel tank, but didn't speak about the ability to read the additional fuel. While your post addresses a possible reason for it, his concern seems to be more about having 9 ish gallons of fuel in the tank when it's telling him it's empty.

 

[JeffN]

A detail that I did not include is that I have a mega cab, 31 gallons is the only available tank size from Ram (I mistakenly wrote 32 gallon in my original post.)

I get that you're trying to keep this thread on track, but the OP himself encouraged people to discuss how often they fill up in post #19.

FWIW, the OP didn't ask anything relating to the larger fuel tank option. He specifically asked how the fuel gauge reads the fuel level. He mentioned he has the larger fuel tank, but didn't speak about the ability to read the additional fuel. While your post addresses a possible reason for it, his concern seems to be more about having 9 ish gallons of fuel in the tank when it's telling him it's empty.

 

[20Blackout]

This thread went south in a HOT second.

F.W.I.W., my 2015 has a 3-4 gallon cushion it seems. 9 gallons is alot.

Seems the current generation fuel gauge reads differently than the last generation. I had a 33-gallon tank in my 2015 Limited and, if I would fill it up when the gauge read 1/4 tank, it would take 25 to 26 gallons. So it truly was 1/4 full. With the 33-gallon on my 2020 Limited, if I fill up when the gauge reads 1/4 tank, it only takes 20 to 21 gallons.

Seems to move very quickly from full to 3/4 full, but barely moves between 1/4 full and empty. Last time I drove it down, just to check...display said that I had 55 miles to empty, gauge was just under 1/8 full and it STILL only took 27 gallons.

Kind of annoying, but rather have it this way and fill up early than run out of gas when the gauge still shows 1/4 tank...

 

[Dr B]

Not sure if yhis could be relevant but I have noticed on my 1500 that the position of the **** handle inside the filler tube of the gas tank makes a difference when the pump shuts off. If I barely put the pump handle in the filler tube it will shut off sooner than if I jam the pump handle as far down inside the filler tube as I can.

 

[Booms]

**** handle...

 

[NWhunt]

Sent from my iPhone using Tapatalk

 

[JeffN]

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.