FUEL GAUGE INACCURATE

[rickg gmparts]

just looking to see if i'm the only one with a terrible reading fuel gauge. I've had it at half and can only put 10-11 gallons in it and I've had it at 3/4(or slightly above) and put 21 gallons in it. 1700 miles on truck. before I complain about it, figured I'd ask here. I checked in my service manual for bulletins and din't see anything- can be confusing to hunt down something like this being a parts guy

[2020-2500]

Fuel gauges suck on most new vehicles.  My truck goes well beyond full, and when it's on E there's still like 8 gallons left of something.  Guess they're trying to keep idiots from running out of gas.

[rickg gmparts]

7 minutes ago, 2020-2500 said:

Fuel gauges suck on most new vehicles.  My truck goes well beyond full, and when it's on E there's still like 8 gallons left of something.  Guess they're trying to keep idiots from running out of gas.

my 14 and 17 1500 trucks were actually pretty good. I always have understood fuel gauges are  flaky, but have figured them out for each of my trucks. neighbor down my road has gmc and he keeps looking at fuel mileage left vs looking at fuel gauge because it's so bad

 

[rickg gmparts]

Just now, rickg gmparts said:

my 14 and 17 1500 trucks were actually pretty good. I always have understood fuel gauges are  flaky, but have figured them out for each of my trucks. neighbor down my road has gmc and he keeps looking at fuel mileage left vs looking at fuel gauge because it's so bad

 

I also understand how full means 3-5 gallons coming off full mark and having a reserve of 5-7 gallons for emergencies- but when my needle just comes off full and I put 11 gallons in it, something is not right

[SkidooSteve12]

My gas gauge has been pretty accurate. I have over 8000 miles on the truck and have been tracking my MPG with aCar phone app. I'd at least call and let your dealer know you are having issues with it just to make a record of the issue.

[Limelight]

Mine will give me like 200 miles and only burn 1/4 tank.  Then it drops like a rock from there. It’s like a turbo- starts off slow and then wham!

 

Kind of annoying but is is nice to drive for a few days without the needle moving. Ha!

[redwngr]

For those that aren't happy with the fuel gauge, Is the 'range remaining' number fail accurate?

 

Might help diagnose if it is the sender in the tank or the display on the dash that is the issue.

[Grumpy Bear]

On 6/4/2020 at 1:51 PM, rickg gmparts said:

but when my needle just comes off full and I put 11 gallons in it, something is not right

Yes, something is not right. So have them look at it. Sender, calibrations. 

 

Supplemental Information:

 

 ΔV = V0βΔT

 

1.) Gas volume changes with temperature. Yes the gas in the stations tank is fairly constant but the temperature in your tank is not. The OP's question isn't one of value but of volume. A tank filled in the morning holds more than one filled during the heat of the day. Each 18 F (15 C)  = about a pint of fuel per 13.2 gallons of delivery. 

 

2.) Station pumps are volume delivery and must be accurate within 3 cubic inches of volume on 10 gallons delivered. How much is that? 0.012987 gallons per 10 gallons delivered. 

 

3.) Ground temperature is fairly constant but the piping and pump above ground are not. Those first few gallons are less dense yes but more importantly the Vapor Pressure is higher. You've experienced this on a hot day when the pumps automatic shut off kicks you out a half dozen times before it settles in to a continuous pump. 

 

4.) Different nozzles have different attachments/shields/springs/stops the cover or alter the insertion depth of various nozzles. In a fuel neck the diameter of a beer can this is more error than the pumps delivery. In fact if the cover contains the vapor release it can be a half gallon different than pulling it back a half inch. 

 

5.) How she sits at the pump. Slope of the vehicle alters fill amounts. Sometimes by a bunch depending on the tanks geometry and actual neck vent location or indention for mounting straps creating vapor pockets. Everything matters. 

 

6.) Error stack. The above five can come in any combination. 

 

However off by 11 gallons is none of the above. For your miles remaining to be a reliable indicator your MPG calculator on board would have to be accurate. Very accurate. It's also worth noting that these miles remaining numbers change with usage. That is you can actually gain miles to empty if you encounter a good distances of exceptional conditions favoring good efficiency. 

 

Note his comment that the venturi effect can be signaled with either liquid or vapor pressure. 

 

 

 

[Dunn]

fuel guage and mpg on DIC are friggen joke.....my 1500 RST was better on both ends

 

I filled mine up to 29 gal from empty and it reads full with 7 gal left to go for actual full level

and DIC mpg is all over the map on same stretch of highway at normal driving......17mpg some days and 10mpg on other days, 

 

no fuel guage has ever been accuarate or consistent to be fair but DIC mpg is complete joke......I drive the same and mpg is all over the map depending on how it feels that day...….for 36 gal tank I get about same mpg as I did on my 22 gal tank with RST overall.....I haven't done the math accurately but it has to be around 10-12 mpg total....pretty sad considering the 6.2 puts out more power and does quite a bit better.....I usually don't really watch this kinda thing but DIC started to piss me off so I got on bandwagon I hate being on. lol

 

 

 

 

 

 

[georgecdisc]

my fuel, battery, coolant, and oil pressure analog gauges all do not match the digital gauges on my phone using Torque app with obdii dongle.

 

I've had 90% of fuel on digital, but analog still on Full. I've gotten used to this over the years with multiple vehicles, and with the advent of fuel range readout I just use that instead. 

 

coolant is probably worst offender and this isn't the only gm vehicle I've seen it on, I think it's typical of all of them going back decades. warming up I'll see 130 digital but analog is already past 160. running temp is 195 but analog is 210.

 

I don't see the point of putting numbers or tick marks on analog gauges if both are inaccurate.