Why do i have bad fuel mileage

I have a 2003 tacoma v6 and i am getting 9mpg or less. I dont have no miss fire or no codes, engine runs smooth, i do mostly city mileage but dam 9 mpg. I have 265/75r16 tires with oem suspension what can i do to improve

 

What were you getting? fuelly.com is a good way to keep up with/track mileage

 

That's a pretty open ended question. Have you kept up on general maintenance? Air filter, spark plugs, wires, injectors, fuel filter, etc? How about fluids? motor oil, transmission, diff fluids? Jacked the truck up off the ground to check for any issues with dragging brakes or worn out bearings?

 

If you can lift the rear of the truck check to see if the rear brakes are dragging.

 

The engine oil looks good and so does thr transmissions recently did my front brakes and werent dragging, air filter still clean, havent vhecked spar plugs yet will try to today

 

9mpg i get around 70-80 miles in half a tank

 

You actually calculating the gas used vs miles driven?

At the pump?

 

Engine and transmission oil looks good recently did my brakes and werent dragging before nor afyer will try to check my plugs today . I also only drive for like 20 mins a day just from and to work which ive read if i have a faulty thermostat the eengine would burn more to try and get the engine to temp

 

Once i fill up i reset miles and get around 70-80 miles on half tank

 

Ahhh. That’s not how I check mpg.

Fill up again note the amount needed. Then use the odometer. All bets are off if you’re odometer is janky.

 

I've seen people do it other ways and it doesn't make sense to me and they also complain of bad mileage. odometer reading fill-up to fill-up seems to be the most consistent. If you have larger/smaller tires that can be accounted for as well

 

Get thinner width tires with smoother tread. Check tire pressure.
Unload any excess crap in the bed.
Make sure air filter is clean.

 

How many miles on the truck?

 

Come on man. Mathing is hard.

 

Everytime I see one of these post, it turns out that the person is driving 90mph. That said, 9mpg is really low.

 

Your mileage continously improves as the tank empties and the truck gets lighter. You are capturing only the worst mileage. Try again and run it to empty, downhill in a tail wind, take a shit before departing, and leave your dog at home.

 

Around 177000

 

I honestly drive under 2k rpms and always try coasting as much as i can

 

Either your engine output is VERY inefficient (check for rich plugs). Or, you have some soaking up the power. Does your engine feel like it's having to work to maintain 65mph?

 

My mind says (in this order):

1. Oil over filled (like a lot)
2. Plugs
3. Injectors
4. Bad Knock Sensor retarding ignition
5. Loss of Compression / Bad Ring(s) (Used Oil Analysis may show fuel in Oil)
6. Fuel Pump (inconsistent pressure)
7. Brakes Dragging (But I think you would know it / smell it)
8. Clutch Slipping / TQ Converter not locking up
9. Accessory on a belt is causing drain, drag, draw - like a bad bearing on an alternator, power steering pump, water pump, AC Clutch

Could the cam shaft have slipped a cog on the belt? That would seem to me that it would run rough but not having that timed out would suck efficiency.

You can start throwing parts and money at it guessing, or go to a shop and pay the $300 Diagnostic fee. Look at it this way... That shop fee will pay for itself in two fill ups or less and if your truck is as vanilla as you say, then what ever is draining your economy may be about to take out the engine. Better to fix it now before there is irreparable damage.