i have a 2000 blazer 4x4 2dr. (with the stock z package ... bigger tires) and get increasingly worse and worse mileage out of it. i can't figure it out.
i have replaced the air filter, used fuel system cleaners etc. and still get about 160 to 200 miles on a full tank (10-to 12 mpg!)!!! i got about 250 when i bought it (which i think is still low). if you have the same vehicle, let me know what kind of mileage you get. What should i do? i replaced the fuel pump a few months after i bought it but it was for a different problem.
o2 sensor maybe?

 

How are your spark plugs? Have you looked at your EGR valve? Here is a previous thread on how to clean it:

https://blazerforum.com/m_14926/tm.htm

 

Thanks! If forgot to mention that i have changed all wires, plugs, dist cap and rotor hoping this would help... it hasn't. i will look into EGR right now.

 

When was the last time you replaced your fuel filter?!

 

dang 10-12 mpg thats terrable for a newer truck. i do better then that an mines older. ive heard through the grape vine that some newer chevyshave valve problems that could cause poor mileage but i have no first hand experience with any of this. ive got a friend that knows a ton about fuel systems and such ill ask him what he thinks. hes owned some chevys and had simaler problems.

 

I agree, that is horrible. My truck is a '94 and I consider it to be a beater (for the time being, just got it) and I still make easily 270 miles to the tank.

 

ive got a 26 gallon tank and i can go 367 miles on it if my math is correct thats about 14 mpg and thats in town. all my driving is done in town. have you tried putting a decoder on it? i dont know what it would tell you but its something.

 

Interesting. I have an 00 and I will get about 200 miles per tank with strictly city driving. I've been meaning to replace my fuel filter so perhaps I will jump on that.

 

If your check engine light is on, then get the codes read, and it will tell you if your o2 sensor is causing issues, if it is, it will give you HORRIBLE gas mileage, the o2 sensor went on my old Z34 and when it was dead, I'd get MAYBE 100 miles to a tank of gas...

Otherwise, change your fuel filter...

As for your 250 miles to a tank being low, if that's a ZR2 you're talking about, and all city driving, you're probably doing pretty good...

Heck, on my 2005, for all city driving, I can probably only get 300 or so miles...

 

I'm always leery of gas mileage calculated on a "per tank" basis unless that entire tank is used for one driving situation. For instance, if you're on the freeway for a 300 mile trip, that's the time to check highway gas mileage. Mix in a bit of town driving and you confuse the situation, or at best get a "combined" figure.

But I agree, that sounds low. For mostly in-town with a bit of highway on a tank, my '99 with 118K miles probably runs about 15-16 MPG. If I do maybe 50/50 highway and town, it's probably 16-18.