2002 Chevy Trailblazer,2WD,92K miles. My gas mileage is ridiculously poor on 2002 Chevrolet Trailblazer

I am getting about 8-10 miles/gallon or maybe 180 miles to the tank and I can't figure out why. In the last 2 yrs it has gotten worse. The system is not producing any codes and I don't have any check lights on but I know my truck (I bought it brand new in '02) and the gas mileage was never this bad in the earlier years. I have had it checked out but mechanica can't finds anything even after replacing the fuel filters. I think it's a fuel pump going bad because the "empty" will come on when I need gas and when I start it later it will be off and the needle is a little higher. Slightly erratic gas needle but not obvious by any means.

by in Germantown, TN on August 29, 2011
3 answers 3 comments
ANSWER by on August 29, 2011
Fuel level sensor issues are not uncommon for the 2002 Chevrolet Trailblazer. That however should not affect your actual fuel mileage. The calculated fuel mileage may be incorrect if you are using the fuel gauge to determine the fuel used. The most accurate way to calculated fuel mileage is to use the trip meter to register the miles driven between fill-ups and the gallons filled at each fill-up. On board system are only as accurate as the fuel sensor readings, which in your case are incorrect.
COMMENT by on August 29, 2011
Thank you for the reply. The only reason I didn't think it was a fuel level issue is because when the light comes on and the needle shows empty, I can go fill up and it takes the whole 15 gallons. Is there anything else that could cause such poor gas mileage. I thought it might also be a fuel pump issue or maybe the injectors are spraying too much fuel than it needs to power the truck. Any thoughts on that? My mechanic followed the fuel lines and found no gas leaks of any kind
COMMENT by on August 29, 2011
The engine computer should compensate do a pretty good job of compensating for fuel system issues that could cause reduced fuel mileage. If to much compensation is required the Check Engine Light will turn on and fault codes will be set. One exception to this rule can be a failed oxygen sensor. I would be wise to have your local repair shop check the oxygen sensor operation.
COMMENT by on October 29, 2012
is the air filter dirty? You may be running a rich mixture [ not enough air for the gas to burn] Check and or change the air filter. not a costly item!!!!!!
ANSWER by on April 26, 2014
any check engine lights on, may just need a tune up
ANSWER by on March 16, 2015
I see no answers here and this hasn't been helpful at all... I'm getting hardly 10 mpg... Can anyone explain what's going on? I had a friend that had a similar size SUV of another maker (Pacifica) experiencing the same horrible gas mileage everyone was thinking transmission, tune-up whatever; however, they vehicle showed a code for the catalytic converter during the complete computer diagnostic test … Sure enough order the item had it installed ..WHAM-O… problem solved.. Does anyone know what solves this problem for the 2003 Trail Blazer 4.2ltr? Please help a single mother three kids and need the help seriously.