60 miles on 1/4 of a tank?!?!

[bpwj76]

I'm getting really worried about my gas mileage. I have only been getting the rpm's up to 2K max during the break-in period and I was only able to get 60 miles out of the first 1/4 tank of gas. I'm at 85 miles now on the same tank and 3/8 of gas is gone according to the gauge.

Do our trucks just have fast moving gauges at first and then slow down towards the bottom of the tank?

[TUNDRATTU]

I would not worry about it right now...chances are after break-in, it should start getting better mileage. That's what I have encountered with other new vehicles I have purchased.

[bpwj76]

I can understand 13 or 14 mpg during the break-in, but not 10. Maybe it is 13 or 14 and it's just too early to tell right now. I'll just have to wait until I finish this tank to see what's up.

I fully expect 15 or 16 once the break-in period is up though.

[skinny22]

You may not have had a full tank to begin with. If the dealer filled it, you can be sure they only put enough in to get the guage near "F". But I made sure my tank was full and burned 3/4 in 200 miles so I'm a bit worried too. Of course you can really only be sure by doing the math on fills over a several tanks. That will adjust for whether or not one pump fills the tank further than another.

[bpwj76]

Originally Posted by skinny22

You may not have had a full tank to begin with. If the dealer filled it, you can be sure they only put enough in to get the guage near "F". But I made sure my tank was full and burned 3/4 in 200 miles so I'm a bit worried too. Of course you can really only be sure by doing the math on fills over a several tanks. That will adjust for whether or not one pump fills the tank further than another.

I'm on the tank that I filled up myself, so I know it was full. I found out the hard way that you can only click the pump once after the initial click when it's full. I tried to click twice and got gas all over the side of the truck

[skinny22]

I've had vehicles before that foamed a lot and it was very difficult to really get a full tank. The fact that it spilled after one click really indicates that might be the case.

I'm still wondering if mine was full even though I tried to top it a couple extra times. It was 10°F and windy as hell, so I wasn't trying too hard. Even if it does foam, after a few tanks it will average out because you'll essentially never get a full tank unless you do the wait routine. My Cherokee was like that and it sucked because the tank range wasn't good even though the mpg really wasn't all that bad. I had to wait several minutes and then I could get an extra couple of gallons in the tank.

[Busa01]

If you look at the tank, it's covered with a skid plate but looks pretty equally dimensioned. However, I do notice that from a half to a quarter tank drops within the blink of an eye. Then the last quarter seems to last forever. So, the tank is definitely shaped funny, even though it doesn't appear that way. Just wait until you run through your whole tank and then refill it and take a mileage reading.

Thanks,

Tom

[mmarlatt]

Originally Posted by bpwj76

I'm getting really worried about my gas mileage. I have only been getting the rpm's up to 2K max during the break-in period and I was only able to get 60 miles out of the first 1/4 tank of gas. I'm at 85 miles now on the same tank and 3/8 of gas is gone according to the gauge.

Do our trucks just have fast moving gauges at first and then slow down towards the bottom of the tank?

On my truck the gauge works as follows,
100%-75% = 80 miles
75-50% = 105 miles
50-25% = 105 miles
25-less = About 60-70 before out of gas light.

[thackl]

My gage is slowest at the top, fast in the middle and somewhere in between at the bottom. @ 2500miles, I'm getting a regular 13 around town (lots of stop and go, but not mashing it) an 18-20 on the highway.

[chuff]

My gauge is slow the first 1/4, medium in the middle and pretty fast on the last 1/4.

[GeneC]

Originally Posted by bpwj76

I'm on the tank that I filled up myself, so I know it was full. I found out the hard way that you can only click the pump once after the initial click when it's full. I tried to click twice and got gas all over the side of the truck

I get about 130 miles more or less on a quarter tank mixed driving. About 200 miles again more or less on a half tank, I think it is showing 190 now on a half tank. If you only got 60 and it doesn't get better immediately, head back to the dealer. I have never seen mileage from mine as bad as what you are seeing. I have 3K on mine.

Gene

[sooner4x4]

Several good comments here about the non-linearity response of the gas gauge to the actual amount of fuel in the tank. I have observed this on every car I have ever driven.

Drawing a conclusion about a vehicle's mileage based on one or two fillups is completely useless. There are way too many variables that will affect the "observed" mileage.

1. How quick the pump shuts off (usually a function of how quick the fuel is coming out of the nozzle which is highly variable)
2. Parked on an incline (even a slight incline) while refueling. Not all gas stations are completely level.

Either one of the variables above could differ the amount of total fuel delivery by 1/2 to a full gallon. If you are filling up when the tank is still 3/4 full, this variable will have a dramatic change on the "observed" mileage. If you fillup the tank when it is almost empty, the effect of these variables is much less. Do the math.

The number of variables during driving is even greater. Don't forget the affect of weather and the changes to the formulation of gas during the year by refineries.

If you really want a realistic idea of actual mileage, you have to think more long term, and you have to accurately document and calculate fuel usage and miles driven. This is very easy to do using a spreadsheet. You have to be anal about always filling up the tank (most of the time anyway), keeping the receipt with an odometer reading written on it, then transferring the data to a spreadsheet.

It is valuable to have the spreadsheet calculate each tankful mpg. But the actual mileage over time is total miles driven divided by total fuel used. Don't average the tankful averages. Depending on refueling patterns during city driving versus long distance driving, average of the tankful averages could skew the data. The real goal of all of this is to be able to identify if something changes that reduces fuel consumption. Perhaps an air filter becomes dirty, a vacuum line becomes loose, that affects fuel/air mixture, whatever. These issues are not always flagged with a CEL condition.

Getting a little more serious with the data, you (the spreadsheet) could easily calculate the standard deviation, and determine if low mileage on a tankful is within typical variability or if indeed something has changed. A graph could be generated and you can "see" changes during the year due to weather or watch the mileage climb over the first few months as a new engine is broken in.

Looking at my own spreadsheet, during 2006, I have filled up 8 times, using 130 gallons of gas, and am averaging 17.5 mpg (Double cab 4x4). 25k on odometer.
Lowest tankful mpg 16.6
Highest tankful mpg 18.5

[Busa01]

Originally Posted by mmarlatt

On my truck the gauge works as follows,
100%-75% = 80 miles
75-50% = 105 miles
50-25% = 105 miles
25-less = About 60-70 before out of gas light.

Our trucks have 26, and change, gallon tanks. Given your tank was considerably full, you're getting about 13.85 MPG on an average full tank. Man, I need to check mine now because that's just not good. I was getting that with my F150, 7 1/2" lift kit and 35" Pro Comp tires with a fully modified motor and Diablo chip with advanced timing and running 93 Octane. So, if my Tundra is getting that pretty stock, then I'm not going to be very happy. Not happy at all.

Tom

[Busa01]

Originally Posted by sooner4x4

Several good comments here about the non-linearity response of the gas gauge to the actual amount of fuel in the tank. I have observed this on every car I have ever driven.

Drawing a conclusion about a vehicle's mileage based on one or two fillups is completely useless. There are way too many variables that will affect the "observed" mileage.

1. How quick the pump shuts off (usually a function of how quick the fuel is coming out of the nozzle which is highly variable)
2. Parked on an incline (even a slight incline) while refueling. Not all gas stations are completely level.

Either one of the variables above could differ the amount of total fuel delivery by 1/2 to a full gallon. If you are filling up when the tank is still 3/4 full, this variable will have a dramatic change on the "observed" mileage. If you fillup the tank when it is almost empty, the effect of these variables is much less. Do the math.

The number of variables during driving is even greater. Don't forget the affect of weather and the changes to the formulation of gas during the year by refineries.

If you really want a realistic idea of actual mileage, you have to think more long term, and you have to accurately document and calculate fuel usage and miles driven. This is very easy to do using a spreadsheet. You have to be anal about always filling up the tank (most of the time anyway), keeping the receipt with an odometer reading written on it, then transferring the data to a spreadsheet.

It is valuable to have the spreadsheet calculate each tankful mpg. But the actual mileage over time is total miles driven divided by total fuel used. Don't average the tankful averages. Depending on refueling patterns during city driving versus long distance driving, average of the tankful averages could skew the data. The real goal of all of this is to be able to identify if something changes that reduces fuel consumption. Perhaps an air filter becomes dirty, a vacuum line becomes loose, that affects fuel/air mixture, whatever. These issues are not always flagged with a CEL condition.

Getting a little more serious with the data, you (the spreadsheet) could easily calculate the standard deviation, and determine if low mileage on a tankful is within typical variability or if indeed something has changed. A graph could be generated and you can "see" changes during the year due to weather or watch the mileage climb over the first few months as a new engine is broken in.

Looking at my own spreadsheet, during 2006, I have filled up 8 times, using 130 gallons of gas, and am averaging 17.5 mpg (Double cab 4x4). 25k on odometer.
Lowest tankful mpg 16.6
Highest tankful mpg 18.5

Great post for sure. But, I'm sorry I had to put my pocket protector on before I could finish reading it hee hee

Not all of us are into spreadsheets and nickle and diming that much where we're going develope a spreadsheet simply to track gas mileage. Seems really stupid if you ask me. My truck gets what it gets. I'm hoping on the motorcycle for a ride out to the dropzone for some skydiving. I don't waste my time in front of computers creating useless spreadsheets.

Sorry man, I had to bust on that!!

Tom

[bpwj76]

It looks like I'll hit 110, maybe 120 by the time the needle hits 1/2 tank.

I'm starting to think I just didn't fill it up all the way. Another reason I think I didn't fill it up all the way is that when I filled up, the needle was right between 1/4 and empty. There should have only been about 3.5 gallons left in the tank. Well, when I filled up it only took 18 gallons. It should have taken about 21 or 22 gallons.

I'll give the bubbles some time to go down on my next fill up and see how it goes.