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Engine misses while driving and poor gas mileage

Discussion in 'Chevy C/K Truck Forum' started by Arbitert343GS, Jun 1, 2013.

  1. Arbitert343GS

    Arbitert343GS New Member

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    I have a 1999 Chevy C1500 with a 5.7 and while driving my engine misses(tach bounces around), but at idle its ok. Also Im getting like 7 MPG and I have no check engine light on. What might be the cause of this?
    #1
  2. JimmyA

    JimmyA Member

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    Spark plugs and wires would be my 1st check!
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  3. Arbitert343GS

    Arbitert343GS New Member

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    Sorry, I forgot to say, I also just put new spark plugs, wires, cap, rotor, fuel pump, and fuel filter on it.
    Last edited: Jun 1, 2013
    #3
  4. baumann6

    baumann6 New Member

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    I think I am having the same trouble as you the only thing that sounds different is when I first start it it sounds like it is missing also. I have tried a cap and rotor also as well as a fuel filter and ran some fuel out in a bottle to check for water in fuel but it looked clean. I am maybe thinking a fuel pump but don't want to change it and that not be the problem.
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  5. 4x4squared

    4x4squared New Member

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    just toss a fuel press. tester on it and see if youre running in an acceptable range. another quick check you could do is grab a can of ether and while its idling, spray down your vacuum lines one at a time and see if your idle changes.

    remember, ethers not the best for your engine lol if you find a leak dont keep sprayin :p

    and check that air filter lol doubt its makin you miss but its overlooked a lot and for $10 its worth changing. if your truck cant breathe its gonna drop fuel mileage.
    #5
  6. baumann6

    baumann6 New Member

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    What is the proper fuel pressure for these trucks.
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  7. 4x4squared

    4x4squared New Member

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    i wanna say about 10-13 psi for a tbi 350... not 100% sure though
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  8. Pikey

    Pikey Moderator

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    I would also consider checking your egr valve.
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  9. Sirwriter

    Sirwriter New Member

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    For 1988 to 1995 the pressure is 9 to 13; from 1996 and up it is 60 to 66 psi. This is for V-6's and small block 8's.

    Sirwriter
    #9
  10. Crockpot

    Crockpot New Member

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    I would check your carburetor, vac lines, and oil. My truck was having difficulty and I rebuilt the carburetor and it started to work much better.
    #10
  11. SilveradoDreamer

    SilveradoDreamer New Member

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    Take the HEI ignition module out of the distributor and have it tested at your local parts house.​
    #11
  12. micknice27

    micknice27 New Member

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    you also might wanna clean your throttle body, I had the same issue, until I cleaned my throttle body and replaced the IAC
    #12
  13. jsmith4816

    jsmith4816 New Member

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    Any luck diagnosing the culprit?
    #13
  14. baumann6

    baumann6 New Member

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    Just wondering what the IAC is that you changed.
    #14
  15. micknice27

    micknice27 New Member

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    Idle Air Controller
    #15

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