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  1. #1

    Default Very Poor Fuel Mileage on 2003 Silverado

    Hi All,

    I have a 2003 Silverado 1500 4.8L.

    Over the last week or so, I've gone from around 14MPG Average to 2-3MPG Average!

    Exhaust smells strong of gasoline. Poor Power.

    What are the first things I need to start checking? Injector stuck open? Not sure.

    Thanks!
    Current Daily Driver:
    2003 Chevrolet Silverado 1500 - 4WD - 4.8L V8 - True Dual Exhaust Setup, Cat Delete, Cherry Bomb Glass Packs

  2. #2

    Default

    Quote Originally Posted by zachh1020 View Post
    Hi All,

    I have a 2003 Silverado 1500 4.8L.

    Over the last week or so, I've gone from around 14MPG Average to 2-3MPG Average!

    Exhaust smells strong of gasoline. Poor Power.

    What are the first things I need to start checking? Injector stuck open? Not sure.

    Thanks!

    I would First have the Truck Scanned to see if it has any Trouble Codes.......and have you done any maintenance lately??

    MIKE


    99"SILVERADO
    5.3 l 3.73 l G80
    BLACK BEAR CUSTOM TUNE
    SNUGTOP l COLORMATCH l KATZKIN










  3. #3

    Default

    The first thing I did was scan it. Not throwing up any codes. Nothing done lately. Oil Change about 1 - 1 1/2 months ago. I even verified the MPG on a secondary device plugged into my OBD. Shows the same.
    Current Daily Driver:
    2003 Chevrolet Silverado 1500 - 4WD - 4.8L V8 - True Dual Exhaust Setup, Cat Delete, Cherry Bomb Glass Packs

  4. #4

    Default

    Quote Originally Posted by zachh1020 View Post
    The first thing I did was scan it. Not throwing up any codes. Nothing done lately. Oil Change about 1 - 1 1/2 months ago. I even verified the MPG on a secondary device plugged into my OBD. Shows the same.
    With no codes coming-up, you could look at doing some of the following,
    ......
    Check the Fuel Pressure
    .......New Fuel Filer
    ......A Cleaning of the Throttle Body and Injector's





    MIKE


    99"SILVERADO
    5.3 l 3.73 l G80
    BLACK BEAR CUSTOM TUNE
    SNUGTOP l COLORMATCH l KATZKIN










  5. #5
    Legend

    Join Date
    Feb 2008
    Location
    Red Wing, Minnesota, United States
    Posts
    3,356

    Default

    i am surprised the truck will even run, as it would seem apperant that it is running extremely rich. thus I am suprised the plugs are even able to fire as the cylinder must be getting way to much fuel to burn off thus the strong smell of gas. Fuel injectors could be malfunctioning or are jus flowing fuel instead of spraying it as they should. And to not have a code seems weird as well. Is the engine stumbling or choking out? Black smoke out the tailpipe when you rev the gas up? It could be the mass airflow sensor as well as if it has malfunctioned and is reading alot of air flow it will dump in more fuel as well....
    99 K1500 Suburban LT "THE BEAST"
    Hypertech III, K&N, true dual
    285/75/16
    ___________________________
    Jason

  6. #6

    Default

    I noticed a dramatic drop in mpg of my 2003 Silverado 5.3 2wd as well recently. Did you find out the problem??

  7. #7

    Default

    FYI, I had my transmission serviced, and my mileage has returned to normal levels.....
    Life is like a CRAP sandwich, The more bread you have, the less CRAP you have to eat....

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