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

    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?
  2. JimmyA

    JimmyA Member

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

    Arbitert343GS New Member

    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
  4. baumann6

    baumann6 New Member

    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.
  5. 4x4squared

    4x4squared New Member

    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.
  6. baumann6

    baumann6 New Member

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

    4x4squared New Member

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

    Pikey Moderator Staff Member

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

    Sirwriter New Member

    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
  10. Crockpot

    Crockpot New Member

    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.
  11. SilveradoDreamer

    SilveradoDreamer New Member




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

    micknice27 New Member

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

    jsmith4816 New Member

    Any luck diagnosing the culprit?
  14. baumann6

    baumann6 New Member

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

    micknice27 New Member

    Idle Air Controller

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