I'm new and decided to post this and get some opinions of some other people who have some blazers. I had my 99 blazer over a year and a half now but it gets crappy gas milage, about 150 to 170 miles per tank (depends if i run the ac or not) from F to dead E. It is 4 wheel drive but I never use it and I don't stomp it or anything.

I did the tune up (ac delco plugs, wires, cap, rotor, pcv valve,) Just spent hundreds of dollars and put a new fuel injector assembly to replace all of the injectors and fuel pressure regulator, cleaned the intake manifold out while i had it apart, I put all new O2 sensors, new cat converter, new map sensor, new maf sensor, cold air intake, replaced all of the vaccum line at the front of the engine, ran fuel injector cleaner, tried all 3 grades of gas and different gas stations to see if that would help. No comuter codes come up and it runs like a champ. I drive it everyday with no problem. I took it on a trip once and got 290 miles out of a tank of gas on the interstate from Tennessee to Georgia doing about 80. Does anybody have any idea of what else it could be? If I do not get this fixed soon I will have to get read of it. It is killing me on gas.

 

I know this isn't what you are looking for, but there is a vast wealth of information on this Forum. Spend a few minutes (hours) poking around the search function. Click this to gain a Doctorate in Searching

this one covers a lot of what you have done, and maybe a trick or two to look into

this is another fairly new one

You have done a lot already, see if any thing sparks anything. And search like crazy. MPGs, fuel Economy, gas milage, Better MPGs, Crappy Gas, etc.

 

I searched around for hours yesterday. Every post says some stuff that I had already done but forgot to mention, like check tire pressure, fuel pressure, computer diagnostic, tps sensor, and numerous other things that I have already done. I went and talked to the manager at an autozone and he said to reflash the computer. He said that with all the new stuff the computer needs to be flashed so it can learn it has all of this new stuff or something like that. So im going to try that and see where that leaves me. If you guys have any other ideas please let me know.

 

Nowhere in your post did I see an actual MPG figure. 'Miles to the tank' means absolutely nothing. Doing 80mph on the highway is going to suck gas like crazy, so that would explain that part of it. Once you get above ~65mph the fuel usage is going to drop exponentially. Get back to us with some actual mpg readings.
BTW, the AutoZone manager is full of it.

 

Well I do not let it get completely empty before I fill up. I look at the gallons meter at the gas station and it is always about 15 to 16 gallons of gas i put in it each fill up. then driving about 150 miles on that is about 10 mpg. I know it is supposed to get better than that. I got better gas milage when I took it on a trip. Went about 290 miles on 16 gallons ( I remember checking the meter) so about 18mpg on the interstate.

So should I not waste the money on a computer flash?

 

Was that 10mpg tank in a lot of stop and go traffic with you making "jack rabbit" starts? Or were you driving it like there was an egg under the gas pedal? 10MPG is not out of the question if you drive it like you stole it or even drive it gingerly given the right conditions.

A computer "tune" would help overall performance, but may cause you to dip into said performance more frequently causing your mileage to suffer. It all depends on your level of control.

Since you can get 18MPG on a trip, I am inclined to think that your mileage is simply due to the conditions that you are driving it.

 

Yep, a 'flash' and a 'tune' are two different things.

 

I average about 18mpg (according to the trip computer) in a combination of highway and around town driving. I drive fairly cautiously. Anything above about 15mpg combined is fine. I get around 21mpg on the highway.

 

Lets please not get into a "my mileage is" comparison even though the OP did ask. We have a thread specifically on that topic in the Gen Chat section where anyone can look and compare what other trucks are getting for mileage.

 

Thanks for you guys help. I took the managers advice and it worked. I replaced so much at once that the computer would take to long to relearn itself. The flash put it back to the factory settings and made it learn all the new stuff quickly. I am getting about 18mpg now! Im keeping the blazer. Best running vehical ever now. By flashing the computer it also shifts and accelerates better than before.