Sometimes bad MPG from same gas station

First of all things might be very different in your area .

But fuel sales are very competitive Having hauled loads of fuel fuel prices are updated at 2400 every day.

all fuel at the wholesale level is within a few cents. Company owned stations will get first service out of the brands local fuel farm. Also company owned stations can be supported by the company resources.

Independent owned stations can in theory buy from who ever will sell to them. At best a few cents different by keeping the overhead low they can sell cheaper. The down side fuel supplies get tight they are the first to be unable to buy gas.

 

It could be any number of things. Your original posts point towards your favorite gas station being the culprit. Many have said to try another gas station to rule that theory out. What if you're right? If you're coming around to that theory being less than likely, then yes, contaminants in your fuel system may very well be the issue. I'd imagine if the issue were prominent enough, you'd notice the sluggishness/rough idle/o2 codes/etc. Does your CEL work? Any codes? Have a scan tool?

 

Can theses Scan gauges not compute a very accurate fuel mileage ??

This in the only way to know for sure . You must know your mileage per gallon per tank does not mean anything.

a loss of 50 miles per tank is nothing when you have no idea of how many gallons are in the tank when you fuel up. Every Tank of Fuel is used in the very same manor . Traffic the same no road construction the very same routine every day?

Only if your start with a completely empty tank put in 10 gallons run till empty not when the truck starves for fuel and shuts off. Repeat 5 times compute your fuel mileage.

If your filling on almost empty causing dirt to be stirred up the sock on the pump would be blocked and your pump would soon burn out.

 

This is almost useless without knowing how much fuel was in the tank when you started calculating and how much fuel was left in the tank when you filled up, but I’d guess that this difference is within the margin of error of normal driving conditions.

 

Real help - those are not real numbers. keep a journal. Drive the same route every day, at the same time. Log how many gallons each fill was, date, time, and odometer reading. Make daily notes of weather, traffic, amount of time spent idling in the drive through. Log the date and time of each engine start, log the time and odometer reading of each engine shut-down. Make a note if it was city or controlled access freeway. Count the number of stoplights and stop signs that you encountered.



Or, if you dont feel like doing any of that, you could accept that a deviation of 50 miles per tank after a fillup that's inconsistent to ± 3 gallons is statistically insignificant and completely normal.

 

As people have stated, forget about this “miles to a tank” crap and actually hand calc your actual fuel mileage at each fill up. These fuel gauges are notoriously inaccurate and unless your driving from a full tank to the point the engine shuts off from running out of gas you have no idea how many miles to a tank you would actually get. Hand calc the actual fuel mileage over the next few fill ups and see what the results are. My guess is it probably won’t be as drastic of difference as what you think your getting based off of where the needle is pointing.

I don’t know if it’s a Toyota thing, but I didn’t even know people considered guessing off of the fuel gauge compared to the odometer was your fuel mileage until I got a Toyota and joined some forums/pages. It blows my mind how many people talk about miles to a tank without ever doing the simple math to know the actual economy.