Ok, I have a 93 4x4 jimmy with the 4.3 vortec. It has 127000 miles on her and seems to be getting about 8-12mpg what do I need try first to get some decent mileage out of her?

 

If it were me, I would start with a full tuneup, including;
cap
rotor
wires
A/C Delco plugs
oil and filter change
injector cleaner in the tank

Before doing all that, start with a Seafoam treatment of your intake system. This stuff works wonders!

Something else you might want to think about having is your catalytic converter checked out because of the high mileage of your Blazer. Having a clogged, poorly functioning converter can rob you not only of gas mileage but of power too.

 

Check for any codes first.
I wonder if the engine is running cold, or if the coolant temp sensor thinks the engine is cold and feeding the injectors to much fuel. Is it black at the tailpipe?

 

my truck has similar gas milage and about 7 years newer...I used to get bad gas milage when my transmission blew..the mechanics found the my front ax.e was always engaged...4wd with out it realy being in 4wd...they fixed it...and now I average 18-20 to 24 depending on how and where I am driving...my worst day with boats on top pulling a u haul...I got about 16...something to look into...

 

engine not warming up? If not I would change the thermostat and radiator cap

 

for a quick mpg fix, try simply replacing simple and cheap emissions parts like the egr, o2 sensor, pcv valve, air cleaner, vapor canister, vacum hoses, etc... and if still no luck try scanning for codes, if u come across a code 44 then check any sensors, map, throttle pos, electronic spark control, idle air, spark timing, electric air control. because a code 44 is a lean fuel mixture, code 45 is a rich mix. too much fuel being fed into the throttle body. its a fail safe, when any sensors or switches go the engine runs in "open loop" which sets the injectors in a default fully open position, in return literally swallowing your gas. i would check your o2 sensor first, the pigtails(wire) on them are known to go bad. and you might be surprised on how much that sensor does for the ecm. and ur exhaust can do alot to, make sure if you go with the cat, also go with a new muffler. all that crap in the cat can break loose and get in your muffler. this all helped to a near zero emissions test, no carbon, no no2, no hyd. and this in a 92 with 165,000 and the mpg went from below ten to an average(for an old blazer) 16-18 mpg.

 

My 2000 blazer gets about 16-17 mpg. I'm getting the sense that it could be better. I recently changed the plugs and wires, I'm good about oil changes and the air filter, plus keeping my tires pressurized properly. I'm not heavy footed either. How do you check the O2 sensor?

 

16-18 for me. I understand that is what these things get new so I have learned to live with it.

 

Same here except I got a np203 tcase. so its supposed to always engage the axle. Im putting a part time conversion kit in soon tho. also dont ahve a cat or o2. I could prob get at most 13, it almost seems that it doesnt matter how i drive like i always figured. But back on topic just do your basic tuneup. btw chevy lover, what mpg do you get on yours?

 

hey samurai in order to properly check and diagnose o2 sensor and others; you will need to pick up a gm scanner to read yor vehicles trouble codes. if you just want piece of mind and want to change it anyway; it should be located somwhere on the exhuast pipe inbetween the headers and cat.