2013 Silverado 1500 LTZ terrible fuel economy

[krustysurfer]

Terrible fuel economy

Truck runs lovely and lively.

Data on readout shows 10.2 mpg avg thought my gas gauge was going down rapidly and that someone was stealing gas out of my tank at night haha so I went looking and found the readout for fuel average and saw that it was saying 10.2 miles per gallon.

Are they really that big of gas hogs? Now this is mostly City driving,

Virtually little highway driving should I take it to the Chevy dealer and have them do a tune-up? I figure that will be quite spendy, actually what I need is a good mechanic in my area who works on GM trucks honestly and with pride of a job well done.

I bought the truck used from an outfit called motor Max I've had the truck for a couple of weeks and have literally only driven maybe 200 miles since then and I've gone through almost a whole tank of gas I'm flabbergasted at how much fuel has been used so any and all wisdom will be considered thank you in advance Timothy

 

 

[Douglas Nathan]

That's an "in the moment" reading it is not average mileage. Turn on the mileage readout while going down a hill with your foot OFF the gas. You get crazy reading of HUGE gains in mileage. Nobody averages the numbers you're going to see. If you want to know your average and it's not exact here's what you do:

1. Fill your fuel tank (to the pump cutoff level)
2. Reset the trip computer
3. Drive until fuel is required
4. Fill the tank again (to the pump cutoff level)
5. Make a note of the number of gallons used to re-fill and the miles on the trip counter
6. Reset trip
7. Use the formula below to calculate mpg using your numbers
8. Repeat this four or five times to give you a good average

The formula to calculate gas mileage: Miles driven ÷ gallons used to refill the tank.

Take the miles traveled (from the trip computer), divide that by the number of gallons used to refill the tank.

For example, the trip shows 200 miles since you last filled up, and it took 15 gallons to refill the tank.

200÷15=13.34 which results in 13mpg.

 

[CamGTP]

Trucks those years also use virtual flex fuel and I've seen plenty of them act up causing lower fuel mileage.

 

If the alcohol content readings start to act wonky it can reduce fuel mileage. I've seen them report 40-60% even though the customer was running regular E10 fuels. A reset of the fuel composition usually solved the issue.

 

You need a nicer scan tool to see if this is indeed the problem though.

[swathdiver]

On 11/9/2022 at 4:40 PM, krustysurfer said:

Terrible fuel economy

Truck runs lovely and lively.

Data on readout shows 10.2 mpg avg thought my gas gauge was going down rapidly and that someone was stealing gas out of my tank at night haha so I went looking and found the readout for fuel average and saw that it was saying 10.2 miles per gallon.

Are they really that big of gas hogs? Now this is mostly City driving,

Virtually little highway driving should I take it to the Chevy dealer and have them do a tune-up? I figure that will be quite spendy, actually what I need is a good mechanic in my area who works on GM trucks honestly and with pride of a job well done.

I bought the truck used from an outfit called motor Max I've had the truck for a couple of weeks and have literally only driven maybe 200 miles since then and I've gone through almost a whole tank of gas I'm flabbergasted at how much fuel has been used so any and all wisdom will be considered thank you in advance Timothy

 

 

 

It's the fender flares, they are costing you 7 mpgs per side!

 

Just funnin' ya!

 

Ten miles a gallon in stop and go city driving is certainly possible.  It really depends on where you live and how you drive.

 

Does that thing have 3.08 gears or 3.42 gears?  The former is not great for city driving and better for highway driving.  The 3.42 gears are the opposite and make the truck feel more lively.

 

Start recording the data on your DIC between each fuel stop.  This will help you see a usage profile based on your driving habits and how the truck if performing.

 

Record your Odometer, Trip Odometer, Engine Hours, Fuel Used, Trip Time and Average MPGs. 

 

With that data you can determine how many cents a mile it is costing you to drive, your Remote Start Fuel Usage, Gallons Per Hour, Average Speed, Percentage of City and Highway Driving, etc.

 

On Fuelly, I was able to determine that the average fuel economy of all 5.3 powered GMT900 wagons for all types and years is 13.4 MPG.    

[krustysurfer]

Thats great information/observation thanks for passing that along!

 

Yeah those fender flares I had a suspicious feeling were the cause of my fuel consumption woes! Maybe a very narrow two track can sort that issue out!

 

With all that being said, we're in the Midwest and it's pretty flat around here so it's not a lot of hills that's causing the issue. 

It definitely could be the gearing! like I said the truck is very lively with the 5.3 l V8 power plant, I have not done the research to see if my vehicle will run flex fuel there are no placards nor decals on the truck saying that it will run e85 I don't know if I want to even do that though because that high alcohol content in the fuel is hard on engines and I would like to get as many miles out of this thing that I can considering the price I paid.

 

I basically got the truck for half price it being 9 years old with 152,000 mi on it, with the window tints and other fancy schmancy accoutrements the thought crossed my mind that it could very well possibly be a former cartel member personal ranch vehicle? Ha! 

 

Anyways, thanks for the advice the fenders came on the vehicle, I guess I could always remove them and gain 10 more miles per gallon (if it really were that easy!) Bwahahahahahahahahaaaa!

 

Blessings snd Aloha 

Edited November 12, 2022 by krustysurfer

[krustysurfer]

On 11/9/2022 at 7:22 PM, CamGTP said:

Trucks those years also use virtual flex fuel and I've seen plenty of them act up causing lower fuel mileage.

 

If the alcohol content readings start to act wonky it can reduce fuel mileage. I've seen them report 40-60% even though the customer was running regular E10 fuels. A reset of the fuel composition usually solved the issue.

 

You need a nicer scan tool to see if this is indeed the problem though.

Great information!

I suspect it's something like that!

It really is only getting 10 mpg city flatlands, filled tank and proceeded to only get 220 miles on that full tank, so the milage tracking software is not lying about fuel usage...

Not too many downhill areas where I can get that 60mpg fuel savings, have to climb up that hill to go down it again..........

Truck runs absolutely strong, however gas at +$4.00 gal is a real bumski.

Thank you for the advice, and nowmhow to remedy the situation? 

Im not a mechanic nor do I even have a garage to work on the truck.

Thank you again, happy holidays

Timothy

[krustysurfer]

On 11/9/2022 at 6:14 PM, Douglas Nathan said:

That's an "in the moment" reading it is not average mileage. Turn on the mileage readout while going down a hill with your foot OFF the gas. You get crazy reading of HUGE gains in mileage. Nobody averages the numbers you're going to see. If you want to know your average and it's not exact here's what you do:

1. Fill your fuel tank (to the pump cutoff level)
2. Reset the trip computer
3. Drive until fuel is required
4. Fill the tank again (to the pump cutoff level)
5. Make a note of the number of gallons used to re-fill and the miles on the trip counter
6. Reset trip
7. Use the formula below to calculate mpg using your numbers
8. Repeat this four or five times to give you a good average

The formula to calculate gas mileage: Miles driven ÷ gallons used to refill the tank.

Take the miles traveled (from the trip computer), divide that by the number of gallons used to refill the tank.

For example, the trip shows 200 miles since you last filled up, and it took 15 gallons to refill the tank.

200÷15=13.34 which results in 13mpg.

 

My truck has a fuel avg readout among the many many other readouts.

I filled the tank and ran it down fuel avg was not lying, 10.2 mpg avg.

Yeah the real-time mpg display option wildy fluctuates sometimes showing 60mpg... but thats 4cyl going down hill with strong wind at my back  

Thanks for the advice, I thinks its the fuel composition sensor that needs resetting especially since winter is now here. High alcohol content in most fuels = bad gas mileage and malfunctions...

Aloha and Mahalo Timothy

[newdude]

On 11/9/2022 at 4:40 PM, krustysurfer said:

 

Data on readout shows 10.2 mpg avg thought my gas gauge was going down rapidly and that someone was stealing gas out of my tank at night haha so I went looking and found the readout for fuel average and saw that it was saying 10.2 miles per gallon.

Are they really that big of gas hogs? Now this is mostly City driving,

Virtually little highway driving

 

 

 

Your answer lies right in front of you.  Driving conditions dictate MPG results the most.  If you go and open it up on the highway for say 200mi, you will see that illustrious 18-20mpg average.  

[It's Tim]

On 11/12/2022 at 1:47 PM, krustysurfer said:

Anyways, thanks for the advice the fenders came on the vehicle, I guess I could always remove them

Flares are covering the rust, best if just left alone...

[swathdiver]

On 11/12/2022 at 1:47 PM, krustysurfer said:

It definitely could be the gearing! like I said the truck is very lively with the 5.3 l V8 power plant, I have not done the research to see if my vehicle will run flex fuel there are no placards nor decals on the truck saying that it will run e85 I don't know if I want to even do that though because that high alcohol content in the fuel is hard on engines and I would like to get as many miles out of this thing that I can considering the price I paid.

 

Your truck is FlexFuel and the engines love the stuff.  The tell take sign on older trucks was the yellow gas cap.  By the time yours was built, the non FlexFuel engines were dropped. 

 

Ethanol does not harm them in any way and after a couple of tanks, it will run like a different vehicle, even the transmission.  It's literally like cheap race gas.

 

But your 10 mpg city driving will go to 7 mpgs or so!  You have to figure out cents per mile to see if it's worthwhile cost wise to run it, it sure is fun wise!  

[Douglas Nathan]

Alcohol/ ethanol just doesn't have the energy gasoline has so more will be burned. Which is better for the ecology? MORE ethanol/alcohol mixed with LESS gas or just gas? Is diluting gasoline with a lower grade energy fuel better or worse? I can't recall seeing a reliable study made by a disinterested group. The pro gas side will tell you what they want you to hear as will the pro alcohol/ethanol side will.

I had a 07 Chrysler with the Mitsubishi 3.6 V 6 in it. using REGULAR pump gas that contains up to 10% ethanol. I replaced the OHC drive belt at 100k miles as required by the MFR. While aligning the timing marks for the cams debris from the combustion face of the heads fell into the cylinder in such a amount that the pistons would not pass TCD requiring the removal of the heads so the cylinders could be cleaned; a MAJOR PIA and expense!

[richard wysong]

Alcohol burns much cleaner than gasoline but is corrosive. I doubt your Mitsu problem was caused by fuel, Excess carbon will build up if the engine isn't exercised by going wide open throttle occasionly to remove it Low grade non detergent gas can cause excess carbon deposits on the valves

[redvett]

When you fill or add fuel the drivers information average and instant fuel info must be reset or the fuel usage will be inaccurate.