Fuel Consumption Help

[Jonah52]

Alright, so I've had my 07 Yukon Denali a few weeks and something keeps puzzling me!

What size is this tank? Right now I am driving a lot of city and my read out says 13.3 mpg. As I hand calculate it i currently have 227 miles logged on this tank and have used 16.4 gallons of fuel; an average of 13.8 mpg- hand calculated. If I have a 26 gallon tank that means I have roughly 9.6 gallons of fuel left and my fuel gauge is below a quarter. My readout says (approximately) 77 miles left to empty. which means if i am getting 13.8 mpg that i will use 5.5 gallons of fuel.

So that puts me at just 304 miles on 21.9 gallons of fuel (assuming I can travel 77 miles before empty). If this is the case where is the other 4 gallons of fuel (26-21.9 gallons used)? I brought the truck home and the light was on empty and it only took 20 gallons before it would not allow more fuel, even after topping off.

Understand, I know this is not a "mileage getter" but I am a stickler for numbers and I'm trying to figure out why my fuel usage, gauge reading, and everything else is off.

If I'm getting 13.8 mpg and its a 26 gallon tank I should be getting around 330-345 miles per tank using 24-25 gallons. This is all strictly city driving too.

So what's the deal? Is my tank smaller than I think, are my calculations wrong, or whats going on because I'm losing 4 gallons of fuel somewhere!

 

[07Burb]

You have a 30 gallon tank

 

[Jonah52]

You have a 30 gallon tank

There is no way.....how could I be at less than a quarter of a tank, only traveled 227 miles and used 16.4 gallons. It's not an XL...

 

[07Burb]

Disregard...you DO have a 26 gallon tank and I'm of no help lol

 

[Jonah52]

Disregard...you DO have a 26 gallon tank and I'm of no help lol

Lol Suburban owners...i tell ya.

Is it possible the DIC isn't spot on with the amount of fuel used? I don't trust it's calculation for average mileage, but I guess the amount of fuel used could be askew or "predicted", yes?

 

[07Burb]

Yes very possible! I know mine isn't exact by any means so I don't pay attention to it all other than just needing a rough guesstimate on the fly while driving

 

[Jonah52]

Yes very possible! I know mine isn't exact by any means so I don't pay attention to it all other than just needing a rough guesstimate on the fly while driving

I'm between filling up tomorrow or waiting for the light to be on....Then I will have an exact amount of miles and an exact amount of fuel. Is it true it's bad to top these trucks off, and that when the pump clicks it really is full?

 

[07Burb]

No that's jibberish. I top mine off every single time and have had 0 issues.

 

[Jonah52]

No that's jibberish. I top mine off every single time and have had 0 issues.

Ok, I have heard it can mess with the float, but wasn't sure. I just wish these gauges weren't so off. Every GM I have had the gauge moves quick and pauses and then you never really know what you have...

 

[tsuintx]

The fuel gauge seems very sensitive, too. My wife's Tahoe could show half a tank on level ground, but when parked on the driveway, it drops almost to quarter tank.

And no, my driveway is not on any extreme angle, either.