Howdy,

Yes, this is another poor gas mileage post, so I will get right to the point.

My 1990 Toyota 4Runner with 3.0 V6 is getting only around 13 MPG. The strange thing is, the truck runs great. Everyone complains about 3.slow, but I can max out the speedometer on level road. The truck has ample acceleration and cruieses effortlessly at 75+ Mph. In short, plenty of power for a truck.

Now, it does not seem to matter if I am driving at 55 MPH with light foot or at 85 MPH with heavy foot. It seems to make no more than 1 MPG difference. It also does not seem to matter if I am mostly on the highway or mostly in the city. Again, 1 mpg difference at the most. The mileage hovers at 13-15 MPG no matter HOW or WHERE I drive.

I took care of the obvious:

1) TIres properly inflatedbe
2) No gas leak
3) Brand new cap, rotor, plugs, wires, the best that money can buy... also K&N air filter
4) Brakes dont seem to be dragging
5) No fault codes of any kind in the diagnostic system

The truck is basially stock. I reasonably expect to get at least 17 MPG average out of it, So I know something has to be wrong, to have such low MPG for a stock truck that runs so well. Any ideas, suggestions, etc? Thanks guys and gals!

 

Well man...I would just say get used to it.

My truck runs GREAT too...no problems at all...other than a relatively small manifold leak.

13 is good...I wish I got that...

I'm gonna do some injector and fuel system cleaner and see what happens.

I also drive with ECT on all the time because I cannot stand not acclerating fast...I dunno why, just a pet-peave (sp?) I guess.

Anyway...

Fink

 

well I hate to tell ya but I think let 13 is about the norm . If you look a couple of threads down is a thread I started about gas milage go there there a couple guys who posted thier milage .

 

I would check out changing the fuel filter, and possibly have your fuel injectors flow-tested and ultra sound cleaned. 13 mpg should not be the best mpg that you see - I regularly get 20, and on a trip back in early August, I got 22 mpg on a tank.

 

ctb can you give the specs on you rig ? AT ? tires ? gears ?

 

1995 V6 4x4, manual tranny, 31x10.5's, 4.56 gears (I'm pretty sure on this)

I don't carry a lot of gear - probably about 50-60 lbs worth of stuff in the back. I don't have a heavy foot either, I drive pretty moderately (my friends even say slow!).

 

I think I have this also. Just from how it sounds. I've checked the exhaust pipes and can't find a leak. Is yours cracked or just loose? (I need an excuse to get headers)

 

Get the fuel atomizer from Haveblue!

Chris

 

You can run 110+ in your 2nd gen 3.slow without hitting the spark cutoff at 106?

I can run to about 103-104 on a good day but it doesnt have enough to reach the cutoff....


I would REALLY check the fuel filter, do the ISR (or FIPK) mod, and possibly a new cat. Also look at your o2 sensor.

I was in the same boat as you 13-16mpg everywhere and an occasional 18mpg. I replaced the o2 sensor, and BAM 23 mpg second tank out on the highway. (The first tank was about 18 and it was SLOOOOOOOOOOOOOOOOOW, then it seemed to have more power after the second tank....)

Steve

3.0 L
4.11
auto tranny
235/75r15 6 ply

 

I did not even know about the spark cut off. Come to think of it, as soon as it got in that 3 figure range, I would ease off accelerator, afraid something would fall off. It sure felt like speedometer was maxed out, but probably not literally.

I will try and replace the 02 sensor.. I was contemplating it but as it did not show any fault codes in the ECU I was hesitant to spend $80 or so to replace what could be a perfectly good 02 sensor.

Thanks to all and keep any replies coming!

 

Wow 13mpg!!! I thought my 90 was bad with 16. Believe it or not my 90 V6 3.0 Auto with 222k mi. on the odometer averages about 15-17mpg. A few things you can check are:

Clean out the gunk inside the throttle body. Any gunk in there can clog up and affect your EGR system.

As you already mentioned o2 sensor. I ran my truck for a while with a bad o2 and I noticed a got a little better mpg once I replaced it.

Check your whole intake system. Mine had a crack in the intake elbow that connects to the tb.

A clogged cat can affect your gas mileage and new ones are fairly cheap if you have a lot of miles on your truck.

Diff fluid? Has this been checked/changed recently?

 

I doubt your O2 sensor is bad. There are ways to test it. Check your manual. You can usually test it using the diag block.

As for 13mpg. If you are an auto, that is about what you will get. 16mpg if you are a manual. I was 13mpg, then I put on 35" tires with 5.29 gears, and guess what. My mileage dropped to 9mpg. And yes, I did do the math correctly. Then I did the supra swap. 90mph at 20% throttle and 16mpg with 38" tires and 4.88 gears.

These 3.0 are dawgs. One of toyotas worst motors.