My first thought was like bearguy. This can be checked by clocking it on a highway with mile markers or have someone follow you and compare.
If it is drinking bad I'd talk to the folks that did the job while still fresh in their mind.
I'm a fan of rebuilding the old trans, but yours was a little worn lol.

Yota guys? Do these have an EGR that gets disturbed during trans R and R?
O2 sensors?

The truck doesn't have a tach. It just has a heat gauge, a fuel gage and a speedometer. I have been running the same basic circuit for the past two weeks with a variance of maybe 20 miles. I normally could make the trip on one tank of gas, but now I have to fill up when I'm about 2/3 through the circuit or I'll run out of gas.

I'm guessing the ratio is lower for the new tranny coming out of a 4 cylinder truck. I think Loosegoose had the ratio correct and the first three gears are lower and 4 th is a 1:1 ratio, with 5 th being overdrive and probably lower than should be with a V6.
I was at a Toyota dealership with my son who bought a new Corolla yesterday. Talk about sticker shock! A new Tacoma is 40 grand now, and no single cabs being made, just double or access cabs(1 1/2 cab). I'm keeping my 2005 Tundra single cab with the 8' bed. New Tundra's are too high to work out of and Tacoma's are too small to haul a snomo in.

Not a Toyota but here is my experience. I had a VW Rabbit 1.4 liter with a 4 speed manual tranny. I got 32 MPG. Wanted more zip so I put in a 1.6 liter with the same 4 speed. MPH went down to 26 MPG. Wanted more zip still and found a 5 speed tranny only to find out it was the SCCA model with close ratio gearing. Got the zip I was looking for but now I was getting 19 MPG no matter how it was driven, high way, town, quick off the line starts or granny roll to get going. No matter, 19 MPG.

I would say that the tranny for the 4 banger in your 6 cyc. is causing the increase. You should see a difference in the RPM's at speed you are traveling. Even a 500 RPM increase over the course of several hours will burn a lot more fuel.

They didn't lock in your hubs on you did they?

You may be able to check the model of transmission they installed. If you have the 3.4 V-6 it would need a R-150F,this will fit first Gen. Tacoma's of either 2 or 4 WD vehicles. If they put a 4 Cyl. trans in, the model is a W-59 . You may be able to look at a photo online and try to match it to what they installed. Hope this helps.

My thoughts as well. seems like the RPM's would have to be considerably higher at highway speed than with the old transmission.

Something I've noticed about this truck is that a lot of times I can't detect differences in engine speeds. It sounds the same to me when I'm doing 75 as when I'm doing 55. Sometimes I'll be doing 70 mph and will notice that I'm still in 4th gear, and had been for quite a while. It's probably just my old age and poor hearing that causes this.

Put your Dobbins Lures sign on this truck, and use it as a business income tax deduction !! LOL

That is a nice looking little truck!

Just for reference, I have a '99 Tacoma with a 2.7L four cylinder, that has 370,000 miles, the transmission has never been touched. It still gets 22mpg.

Paul I feel for ya,its always something aye. gotta be the transmission if that is the only thing changed. they should be able to figure it out....happy easter and good luck on them beaver.

Ever thought of the gas being ; OFF
with all this low barrel head price and fewer people driving the Reserve tanks are filling up, soon the capacity of the tanks will be filled.
Then there is going to be a supply issue of shutting off the well heads.

Try some higher octane fuel.

This sounds real reasonable to me, in theory.
I think what I would do is calculate gallons per hour like is done with fuel consumption in aircraft. Of course you probably don't have a similar record from the old tranny. You need a Hobbs meter or similar to keep track

True.

Paul's saying that taking the same trip he has to stop for fuel where as he didn't before.he

I'll be interested to know what the problem/cure is. My money isn't on year ratio tho.

I think my fuel economy is slipping too. I don't drive a Toyota though.

I'm driving a '76 Chevy step-van with a 4bbl carburated 350, 4.56 gears that top speed is 55mph and I get 13mpg.

Why on earth did they have to start making them look like a dodge. Lost my interest, keep making all the trucks taller, bigger, with a grill that looks like it came off an eighteen wheeler! Auuurrggh!

she

She ain't for sale fella's, my dad bought it new and it only has 32,000 miles on her. It will go 55 p hill and 56 down hill, with the engine screaming! Lol.

lol, Hippie! I used a frame out of one of those on an old truck I was building.

Paul, are you sure they didn't change the rear end too! lol. That's the only way It would change the overdrive very much. Stands to reason that the overdrive may not be geared as high for a four banger compared to the v-6. The more percentage of overdrive, the more it will pull the engine, because it takes more horsepower. I think that may be the difference, but you would have to find the right tranny. I'm still amazed that it would make that big of difference.