Lost MPG 320 to 210 per tank

I Bought my 2010 Tundra Brand new, only owner, been a great truck! But I lost over 100 miles per fill up for no apparent reason its always got good gas mileage for a 4x4 V8 and I've driven it from California to Alaska and back and all over the west Coast! It has 110,000 MLS on it a 3 inch leveling kit that was installed when I bought it and I have always ran 33 12.5 tires on it and a K&N filter thats it, about a month ago I drove 3 hours to pick up a empty 16 ft car trailer and half way home the MPG dropped dramatically, when I got home I reset my mileage and filled the tank and sure enough only 210 till next fill up and this has been going on for over a month and havnt towed the trailer since I bought it so what can it be I do all my own fluid changes and even rebuilt the hole front end last year at a local Les schwab, I have no engine lights on and my truck isn't a flex fuel plus its summer time so the winter fuel issue isn't the problem I live in a modern temp climate 30 miles from the ocean and have owned 8 different Yotas this Truck is my Favorite and I want it back to Normal before I move from Cali back to Alaska nxt Month

 

You were probably getting 5-6 mpg pulling the trailer. The ecu adjusted per what it was seeing the engine use. When you filled up it still thinks you’re getting that mpg. Reset it and you’ll be fine.

 

At 100k time for spark plugs if you have not changed them already. They can certainly impact MPG/performance but not as drastic as your experience. Think Danny is right, likely the towing MPG impact.

 

You can do a double-check test by filling up and noting the odometer reading. And then re-noting it when you fill up. Do the simple math. It would be good to also be checking the fill up quantity of gallons.

 

I can drive an entire tank at 60mph, getting 17-18mpg and the computer will still calculate my range at ~13mpg when I fill-up. Don't stress about the computer, it's always wrong. Do some hand calculations from a few tanks of gas and make sure there's a real problem.

 

one other thing you can do is reset computer- - actually disconnect the battery for 30 minutes. It will clear that mileage estimate and start over from scratch based on your driving.

 

I don’t use the trip computers they aren’t exactly accurate. I always calculated by hand

 

Aaaahhhhhhl Grasshopper very smart!!!!!

You probably also use a Hewlett Packard calculator.

 

I wear flip flops so I can count past 10 haha


Also if you’re towing anything the mpg is affected

 

Welcome from Alaska. What part of AK will you be heading to?

 

Welcome from LA (Lower Alabama)! I think the guys covered it pretty well earlier. If your hand calculated MPGS still show a big drop, let us know. There are some really smart folks on here that will help you figure it out.

 

Welcome from Phoenix

 

Welcome from So Cal.

 

Welcome from Ohio