My 3rz is a gas guzzler

I do know someone with the same engine I will probably ask them to borrow theirs and see if it makes a difference.
With regards to the o2 sensor: when I took off the old one, I could not find the direct replacement i.e same part number. However I was able to find one of same brand (Denso) and wire configuration and connector type. The sensor triggered no codes and voltage fluctuates correctly. Is there any chance that I am doing the wrong thing by using a different part number? I mean, who knows if the one I replaced was even the original!

 

have you checked to see if the E-Brake is sticking? used to happen all the time on my 95, 98, and 02 tacomas. More rolling resistance = worse fuel economy.

 

Occam's razor. Since nobody else has said it, but if you're calculating solely off of your odometer or tripmeter, maybe its counting the miles too slow, giving you an artificially low mpg. Use a GPS and give it a check.

Also what about a possible leak/pinhole in the tank or somewhere in the fuel lines.

Check the simple stuff and work your way back from the fuel tank before you start tearing into the more serious fixin's.

 

Thanks for the responses. I have checked the trip with gps and the odometer is accurate. I was suspecting a fuel tank/line issue, and that will be further investigated on Thursday when I go to the mechanic.
I don't think I have a problem with sticking brakes. With the vehicle in neutral it will comfortably roll.
As you can imagine I am reaching my limit with the poor economy. I appreciate all the useful insight that has been provided thus far. I'll be sure to check on the suggested solutions and report back if any changes came about.

 

Do you have the original O2 sensor?
If the "new" one is shorter than the old one, it isn't in the exhaust stream and not properly measuring. This is a trick that some tuners use to fool the ECU to not trip a "check engine" light as you would be running rich.

I hope it is only a pin hole leak in your fuel line but then that could present other issues...

 

Checked this last week on my 95.. it was in fact sticking a bit.

don't know that it helps or correlates but I also have at 2.7

 

I do have the original, and the new one I put on is almost the same in dimensions. I'll have the mechanic check the e-brake just to be absolutely certain.

 

What trans do you have and what is the gear ratio? Also, are your tires the OEM size?

I was getting the same mpg until I changed the gear ratio.

I had an auto trans w/ 4.30 gears on 265-70-16's. Went to 265-75-16's and it was worse. Installed and ARB locker w/ 4.88's and my mileage went to 20 mpg.

Currently on 285-75-16's with 5.29's and still at 20 mpg.

Hope this helps you out.

 

Thanks for that info Richie. I'm using an auto.. how do I know my gear ratio? I'm currently using 31" tires.

 

There's a tag on your driver's door jamb that has your vin on it and somewhere below that an axle code

For example, mine is A02A. I believe it is kinda buried in a larger string of numbers but shouldn't be too hard to find.

 

You mentioned your trips are short - are they all stop and go? My '99 auto 2.7L Prerunner has been getting bad mileage lately, but 95% of my driving is in awful stop and go city traffic. I've been getting 14-15 lately. When I was driving 99% highway, and I could keep the speed at 60mph (that was tough), I was averaging over 24 mpg. When I was driving a mix, maybe 75% highway, my mpg was around 20. These trucks may have the legendary Toyota endurance, but they sure don't have the typical Toyota mpg. The auto trans/big tire combo probably hurts the most.

 

OEM tire size for my vehicle is 30".
Thanks for the input Drewski, about half of my driving is stop and go. I have a friend who has a 96 tacoma, same tires as me, auto trans, and does the same driving and he averages around 20mpg. I will look into the gearing though. I don't believe there is any sticker in my door jamb, but I have seen methods online which take wheel and driveshaft or crankshaft rotation to calculate the gearing.

 

Found the gear ratio, its in the engine bay marked A04B. So According to this: http://www.4-wheeling-in-western-australia.com/images/diffratiochart.jpg

I'm running the wrong gears and I need to either step up to 33's or step down to 4.11 or 4.27 gearing. This is great news, at least there is a known culprit now!!

 

i have a 2001 with 144,000 miles same tires and i am getting 15 i have done everything you have and have just chalked it up to it is what it is

 

Don't you use a lot of ethanol or alcohol gas there ? that will do it for sure. you know Sugar Gas

 

What you have is a vacuum leak i bet. Are your plugs covered in black soot?

 

No idea on your issue Pravesh, sorry, but I love your truck! Beautiful!!! Thanks for posting a pic, would like to see more if you some.

 

Replace fuel filter. Use fuel injector cleaner such as Chevron Techron concentrate. Clean or replace MAF. Check for vacuum leaks.

 

I know this response is a little late but the woodroof key on my crankshaft sheered off and the crank was spinning free of the pulley. I read somewhere that if one of the pulleys was out of line with the rest it could cause the truck to be sluggish and effect your mpg. After reading this I thought about it and my truck had been sluggish at lower rpms and I could never figure out why my gas mileage was lower than normal. I have since bought a long block and put it in. Now I'm trying to figure out why only one coil pack is firing which is why I'm on here right now. lol. Anyway...I figured maybe one of your pulleys may be loose.