Insanely Low MPG, Can't Get a Clear Answer, PLEASE HELP

Until you do the math and figure out MPG you know nothing. Miles/tank is useless info. You could easily just have a bad fuel gauge.

A 33" tire isn't that big and shouldn't make a huge difference, even with 3.73 gears. Re-gearing isn't usually a need until you get to 35" tires. I've had 32" tires on mine for years with no lift and fuel mileage has never changed. Even with 53 lb E rated tires. In my experience wide tires with aggressive tread is the biggest killer of fuel mileage. The same size tire with a less aggressive AT type tread will often give 2-3 mpg better.

Air pressure can make a difference too. If you're 5 lbs low you could lose 2 mpg.

 

The lift and 33s are killing your mpg - also the winter season. I got 20.4 on my last tank with my 2.7 2wd, usually get 23-24. 150 mile range is bad it could be many things causing that

 

I appreciate that. Here's a pic below. Since purchasing, I've added some stock running boards to help with entry/exit given the lift.

I bought it from a high school buddy of mine. He only had it for a couple of weeks (red flag, I'm aware) but said it was because he decided almost immediately after buying it that it wasn't a big enough truck for what he was wanting to do. He also drives a company vehicle for a DD, so in the two weeks he had the Taco, he drove it a grand total of 18 miles (with a full tank) so he didn't have enough time with it to know about the gas. When I test drove it, I knew there were some bugs but they all struck me as minor (brakes, calipers, etc.) Obviously the last thing I would expect is a fault gas gauge. It's also my FIRST experience with a lifted ride so there were some breakdowns in understanding I've had and continue to have as this situation progresses.

I'll start monitoring the fill up numbers and crunching the mpg's across multiple tanks. I'm super eager to see how many gallons it says I take in the next day or so when I fill up. Thanks for the kind welcome and support, guys! For real.

 

check sparkplugs, throttle body, MAF or better check and replace i they look busted on sparkplugs and clean the TB and MAF. I assume oil and all your filters, air, oil etc are new.

Do you feel your having any starting issues? Deeper stuff could be a bad fuel pump or bad filter sock although I feel you wold have different issues there.

If any of those apply and the truck has big tires, lift, armor etc. as folks said just going to make it worse I was getting 7-9 on my 2013 and cleaned the TB, MAF, and changed out the plug not long ago and the plugs were roasted. My guess is that was a big part of it.

 

That's basically the tone I was getting from seeing other posts on various forums, that a lift of my magnitude with larger tires could* potentially impact 8-10mpg's but it wasn't exactly common for it to be that high. As far as the lead foot goes, that is definitely not my MO. I'm super OCD about RPM's and engine revving, so I'm always consciously trying to stay light on the pedal. I drove a corvette when I was a teenager and racked up 3 tickets and it forever broke me. Now I never exceed a speed limit, even on an interstate by more than 2 mph, if that much.

I will concede that most* of my time will be in city. I live in a rural town comprised of two lane state highways/county roads, promptly seven miles from an interstate in either direction; however, I do make usually bi-weekly trips down said interstate for supplies for my meat market, so my miles actually accumulate on the highway, but most of the drive time is in town.

 

Have not noticed any issues with starting or killing the engine. Fires properly as far as I can tell. I'll give the sparks and filters looks tomorrow. The only thing I've noticed in terms of drive performance is that it feels a little heavy in low gears, but not so much so that I wouldn't attribute it to the heaver tires and resistance drag from the lift.

 

if its slow in the lower its likely def the lift and tires.

I had no starting issues but was curious. Truck for the most part drove fine just had shit MPG 7-9 mpg towards the end of it. Now I get 9-13 mpg but the truck is grossly overweight, 35's S/C so it makes more sense now. Before it was lighter, smaller tires and made no sense.

 

The 33" tire not being "that big" is the point I've been trying to make to a couple of local guys who have been mulling it over with me. They seem comfortable nesting the argument that the Taco is a light enough truck that a 33" to it is comparable to a 43" on an F150 (not their words, but their logic if you follow me). They're posing that the 33" though generally speaking isn't too large, is for a truck like the Taco. Then they add that the increased drag from the 6" lift doubles down and creates the mpg dilemma. My push back is that I know those things will hurt, but I'm not willing to believe just yet that the damage is as drastic as what I'm seeing right this moment. There's got to be one/some other gremlins, which is why I appreciate the feedback for the gauge, pump, filters, etc. etc.

 

Yeah I hear ya I know that when I went with a 2-3" lift and E rate (that is likely the kicker) and 33's My truck dropped from stock mpgs to 12-14 mpgs so it def made a difference the later stuff was even more but I'm chalking it up to the plugs.

 

When my 2018 Tacoma was 6 months old, MPG went down to 14 with lift and tires. OP has a 6" lift. Terrible aerodynamics.

My 01 LC 100 series gets like 10mpg.

 

And if it comes down to it being the lift doing the damage, I'm prepared to scrap it and go back to factory. Only problem with that is that I'll have to find a factory suspension kit to have installed. This one will have to be cut off and new one re-welded. Plus I'll have to sell my wheels/tires because I doubt these 275/60/20's will fit on factory (please correct me if I'm wrong, but visually it doesn't look like that would).

 

On mine, I usually get just short of 12 mpg. After a little bit of effort, I checked the fuel trims, it said to look for a vacuum leak. Found my pvc vent hose worn out, loose, cracking end. Found it when I replaced the plugs recently. For temporary, I repositioned the hose and clamp. The next fill up calculated to about 14.8 mpg. That includes a 2 hour highway drive. The next fill up will be a more accurate assessment. 4.0 v6, 6sp manual.

What I would suggest is to look through the stickies. In the maintenance post, you’ll find instructions how to clean the maf sensor and throttle body, changing plugs, etc. You’ll see plugs are recommended every 30k miles. Unless you’re certain they’re up to date, pull one and look at it. You might find what I did at well over double the mileage. Ngk one side, denso on the other, indicating originals from the factory, and dang, how’s it still run with a gap that huge. I would also suggest to not get spark plugs from Amazone, I received what I suspect were counterfeits.

Nice looking new to you rig. Welcome to the forum.

 

A couple of factors to consider here. Not sure how many miles are on the truck, but that comes into play. A lift and tires absolutely comes into play as well. A general rule I have heard before is that every lb you add to the tire, the rotating mass is equivalent to adding 20 lbs to the bed. These trucks are pretty high riding as it is and more air/turbulence under the vehicle from a lift isn't going to help at all.

Another factor to consider is your location. Colder weather brings winter gas and different fuel mixtures from the ECU which all drag down economy. Colder air also means reduced tire pressures so it's important to double check those.

 

The price you pay to look cool. I’d start with a tune up. Drive like an old lady and see if it improves. My 15 is still stock other than 265/75R16 factory load rated tires and TRD catback exhaust. It gets 20-22 mpgs on 87 top tier gas. It’s got 110K.

 

have you taken into consideration that the larger tires are affecting how many miles you are actually driving?

 

I'll definitely be keeping close eye on tire pressure. I wish weather was more of a factor at this point because that's an easy culprit to identify, but here in MS, we're having 60-70 degree December days, so cold weather has yet to rear its head on these tires.

I'm going to try to learn how to convert the tire difference so I can adjust for how off the tripometer is for the larger tires.

 

That will help with the conversion.

Unfortunately MPG is one of those things which can suddenly be greatly affected by only a few factors. Speed also matters. For example: above 60-70 or so MPG starts to drop pretty dramatically.

 

Hey gang, I just wanted to give an update now that I've ran the tank bone dry and filled up as of this morning (12/19) ... Last night I let the gas light come on and drove it roughly another 20 miles and then went for a fill-up this morning. It took 14.4 gal of fuel before clicking off at the pump. Upon cranking her back up the gauge read completely full.

As I understand it from all of the online research I've done so far, every model of 13 Taco had a factory 21 gal tank. I spoke with the mechanic who did the repair on this truck following its previous owner accident, and he said he never touched the gas tank so as far as he knew it was factory unless someone else changed it out (which would feel unnecessary right?).

So does this play to the notion that the gas float/gauge/arm may not be working correctly? I guess there's a chance I've only got a 15 gal tank, but it certainly seems like a stretch unless there's something I'm not considering.

 

Yup, you should have a 21 gallon. As you said, even my 4 banger has that size. The light comes on at 4 gallons to go.

You've probably looked under it (and I don't think we have metal tanks anyway) but just for funsies I wonder if your tank is dented somehow. Shot in the dark but one of my high school cars had that issue and I learned the hard way.

That said I do believe I'd suspect the float system or perhaps a bad ground, though the latter doesn't sound right.

 

Is this mostly city or freeway driving you do? I imagine those rims are heavier than stock because they are flashy looking. Which is going to take more mpg off compared to the same size tire on a stock wheels.