I just resently picked up a 99 jimmy 4.3 is 11-12 mpg in the city, normal just seemed a little low to me. thanks
mike

Yea I'd say way too low. Heck I get 9-11 MPG out of my 1986 Ford F250 4x4 with a 460 in it.
Our 97 Blazer 4x4 4.3 gets 20-22 MPG. Our 98 Jeep Grand Cherokee 5.9 Limited gets 14-18 MPG.
Are you getting any codes? I would start with checking plugs, wires, & fuel leaks.

Right after I got it about 1 month ago I put in new plugs, checked the wires, new fuel and air filter, no change in mileage. No codes thanks
mike

What temp is it running?

It is running in the 200-210 range

Okay, then.

When you replaced the plugs, how did they look? Were they coffee-colored, black, white, what color?

Also, have you checked your cap & rotor?

I just resently picked up a 99 jimmy 4.3 is 11-12 mpg in the city, normal just seemed a little low to me. thanks
mike

You should be seeing at least 16-18 MPG in the city. Start with the basics. Before you throw a ton of cash at it, you might consider a diagnostic check at a reputable garage, maybe one with an Emissions or Exhaust Analyzer. You could be dumping huge amounts of unburned Gasoline into your exhaust system.

I would also check for vacuum leaks, missing or rotted vacuum lines and hoses, PCV Valve, and maybe a little fuel system cleaner.

Since the Plugs are done, Spark Plug Wires, Distributor cap and Rotor would be my next thought. After that, Oxygen Sensors.

The Plugs that came out all looked really good, the plugs that came out were like a platium plug with the small pionted electord the one the local parts gave me for replacements were just standard plugs, I would not think that would make that much differance. I have not checked the cap and rotor yet, I guess that will be the next step, we do not have smog testing around here, but I do have access to a scanner, is there somewhere I can look to see what the readings should be. It idle and runs great and only has 80K. thanks
Mike

If you did not go back with the platinum plugs AC Delco are highly recommended by most of the guys I know running Blazers then that could be a lot of your problems.

Ok, thanks I will change the plugs this weekend and check the cap and rotor. Is there a place on line that I can lookup the readings ranges that should be if I get a chance to hook a scanner up? thanks
mike

I can't help you with any reading ranges. The reason I say the plugs is the OEM plug for your Blazer was a Platinum AC DELCO Plug.

well got the plugs, cap and rotor changed, cap and rotor needed it so donnt fell like a waste of time or money, will see if things improve. thanks for the help so far.
mike