New Taco and I'm already worried. Help please.

Good point to go through a tank or two to see what is up.
plus your driving vs the other person who put the 6500 on...who knows...
doesn't the ecu learn your driving style?

best of luck with your new truck, do not throw in the towel yet...you gotta post up some pics if you can of your new to you truck!

 

newbee here...

Do you have to somehow calibrate your speedometer/speed sensor if you are running bigger/larger tires? Could that be throwing off his gauges?

Also is it possible the previous owner used a chip to change the fuel mix?

My fuel gauge on my '10 DB 4x4 also starts to dip below Full after 20-30 miles

my 2cents

 

nah, toyota keeps their ecu's locked up tighter than a frog's ass

OP, I'd try resetting the ecu and top off the tank and see what happens then.

 

Sounds like what my 09 is getting, after owning it for less than a month I have been getting 20 - 21 mpg consistently.

 

exactly....Although the numbers the OP has posted seems a little disproportianate....try filling up a new tank and seeing from there, if still dissatisfied, go out a buy a prius.

 

city driving the gauge starts to move around 20-30 miles. Highway driving I have gone 50-60 miles before the gauge starts below the full line.

 

well, how big are those tame tires? does it also have 5.10 gears? Does it have a hole in a piston? If you're worried, get it checked by someone that knows.

 

MY 09 gets 15-19 in town and 21-22 on the highway. I get 17 with my 10x5x6 cargo trailer loaded with my daughters stuff in it. I have 13000 miles on it

 

I did the math. I'm getting about 10 miles to the gallon. This can't be right.

 

I am getting a solid 19.4 to 19.6 on every fill up. Although its all stock there is no way "tame" tires would do that. I would have the stealership check it out. In the meantime try changing the fuel filter. Obviously it sat for a while and may have had condensation built up in the tank or something and its wrecking fuel mileage. I'm used to diesels and this is always the first thing you do so if its not that way with these just call me out

 

whats your height, climate and driving habits like (alot of traffic or piddling around town)? These can all affect your gas mileage.

Let your truck idle, stand behind it and get a whiff of the exhaust, If its real pungent it means your running very rich. Or if you have puff of blue smoke after crank up that could also be a sign that your running a little rich.

Mass air flow sensor wouldn't have anything to do with it? My Tahoe is like that now, but is only messing with the RPMs and a bit of my fuel economy.

 

Exactly...

You are calculating it based on the odometer and not the fuel gauge. Not to be insulting, but I've known people that think the fuel gauge tells them how much gas is in their car. It doesn't.

Now, i did just "fix" a guy's volkswagen fuel mileage problem in another forum. He was diagnosing all over the engine and complaining about the fuel mix in his new home town after driving cross country in his bug. Engine seemed fine.
My guess (mostly because everything else had been diagnosed out)
.. bad wheel bearing...
Tuned out I was right; he had a bad wheel bearing which in turn was causing plenty drag, but it also threw off the rear axle alignment enough where the drum was dragging as well. Was getting less than 20mpg in a bug he claimed usually got 30+

 

Black smoke should be rich.. and yea, it'll make your eyes water.. blue would be a little leaky valve seal (most likely).

Thing is, most any burning condition that would be coming OUT of the engine should throw a code from the O2 sensor. Though it might not bring up the cel yet. Losing 25-50% of your mileage on a poor mix condition should quite noticeable in driving: noise (knock), smell, response, heat. I guess a stuck VVT could do it.. they used to be prone to failure due to poor oil maintenance.

 

Mine fills up past the full mark and doesnt drop below until about 60 miles later. I dont know that doesnt sound right.

 

Disconnect your battery for a few min to reset the ecu, go through a few tanks while it learns your driving habits, see if that fixes it?

 

More details. It's got a 3" spacer lift, 17" wheels, and 265/70/17 Michelin LTX A/S tires. Is this setup my problem?

Resetting the ECU tonight and I'll see if that helps.

 

The tires on mine are 265/65-17 from the factory so its not like you are running anything noticably bigger than factory tires. That shouldn't affect it at all

 

you're sure no one effed with the gears?
I don't know why they would in a pre-runner.. but they could have.

 

Here in Ca, I have tried ARCO gas. I was at a stop light and noticed
the gas gauge dropping. My gas mileage had dropped enough for me to worry to
the point if I was going to make the next town. When I use top tier gas
lasted improved. I use 87octain

 

I filled up yesterday and drove 66 miles home on the highway and my fuel gauge is still slightly about the FULL line.