Lost fuel avg

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Black389, Dec 28, 2017.

  1. Black389

    Black389 Light Load Member

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    hey guys im having a problem. Last week my fuel filter got filled and the red light came on my truck indicating fuel filter is too high. I got my oil changed and now where i used to see my current econ wjen i would drivr it like a grandma id see 5.5-6.5 on flat roads no wind. And now when driving empty with no wind im only getting 4.3. What could be wrong?
     
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  3. Black389

    Black389 Light Load Member

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    And i dont have the power i used too
     
  4. baha

    baha Road Train Member

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    T/stops are using winter fuel is a part of the loss of mpg but ck air filter
     
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  5. Black389

    Black389 Light Load Member

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    Air filters are new. But i have tiny bubble in fuel filter is that normal?
     
  6. baha

    baha Road Train Member

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    If you are trying to use the dash mpg, try to mark mi. in a note book next time you fill truck up and keep all gal.you put in till you fill up next time then ck the mi and it will be the real mpg, but a different type of fuel filter may have been put in your truck making it starve for fuel?
     
  7. BigBob410

    BigBob410 Road Train Member

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    I wonder about the different fuel filter scenario. I was having a lost power issue when my company forced me to get a service at a place I didn't want to go! There truck so not my call...anyhow I had my truck serviced again at our shop and low and behold I have more power again. I wonder if these shops using after market(cheap) filters is causing the OPs issue.
     
  8. wore out

    wore out Numbered Classic

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    If it's got air in the fuel the power will be down, the mileage will be down, the Pyro will be up.

    As a rule if there was no problem then you had work done and their is then go back to that work.

    I agree the dash readout isn't accurate to real mileage. But if it's dropped from before like you describe I think you got a problem
     
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  9. KVB

    KVB Heavy Load Member

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    You mentioned fuel filter was too high and red light came on. And you had oil changed.
    I assume your fuel filter was replaced while doing the oil change?

    This all indicates something is wrong with the fuel filter, or the way it was installed.
    You did notice small bubbles of air in the fuel, right?

    You did not mention what engine you have, air in fuel can have different effects on different fuel systems, but air in the fuel can/will result in lower power/torque (less fuel being injected when at max torque, because of the air).

    During cruising the fuel system will compensate (for the air) with longer injection duration to get the amount of fuel required at your cruise speed into the cilinder. This will show up on your instantaneous and average mpg on the dash, but not so much in real mpg.

    Air in fuel may also result in damaged fuel system parts in the longer run, due to cavitation.
     
  10. PandaPancake

    PandaPancake Light Load Member

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    my dash says I get 3mpg
     
  11. uncleal13

    uncleal13 Road Train Member

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    I had a 2001 ISX. Had an oil change including the fuel filter. They put a Baldwin fuel filter in it. Over the course of the next week, it got harder and harder to start to the point I had to use ether to get it to go.
    I walked into a small shop and inquired about it, the mechanic said the o - rings on the Baldwin filter were too thin for the ISX and would let air in. He put in a fleetrite filter, after that I had no more problems.
    So yes, some aftermarket fuel filters could cause your problem.
    Easiest thing to try.
     
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