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  1. #1
    Jr. Apprentice Arbitert343GS's Avatar
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    Oct 2010
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    Lawrenceville, Ga
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    19

    Default Engine misses while driving and poor gas mileage

    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?
    Brandon - Georgia
    1999 Chevy C1500
    1978 Pontiac Trans Am

  2. #2

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    Spark plugs and wires would be my 1st check!
    2010 GMC SIERRA CREW CAB (Silver) 4x4, ReadyLift 2.5" Level Kit, 305/60/18 Dick Cepek Mud Country, Go Rhino Nerf Bars, Husky Liners front and rear, Bushwacker Bed Rail Caps, SCT Programmer.

  3. #3
    Jr. Apprentice Arbitert343GS's Avatar
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    Default

    Sorry, I forgot to say, I also just put new spark plugs, wires, cap, rotor, fuel pump, and fuel filter on it.
    Last edited by Arbitert343GS; 06-01-2013 at 08:41 PM. Reason: forgot something

  4. #4
    Jr. Apprentice
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    Oct 2012
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    Saskatchewan
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    Default

    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.
    2000 Chevrolet Silverado K2500 Crew Cab

  5. #5
    Jr. Engineer 4x4squared's Avatar
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    Fort St. John, BC
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    Default

    Quote Originally Posted by baumann6 View Post
    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.
    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.



    5.7L 350| .420 Cam | Bored 0.030 | Edelbrock intake manifold | 600 Cfm Edelbrock Carburetor | Long tube headers | Shift kit | Chrome dress up kit | Flowmaster 40's exhaust | Edelbrock heads | Custom paint
    SOLD

    "Don't judge a book by its cover."

    HONORARY CANUCK

  6. #6
    Jr. Apprentice
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    Oct 2012
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    Default

    What is the proper fuel pressure for these trucks.

  7. #7
    Jr. Engineer 4x4squared's Avatar
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    Default

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

  8. #8

    Default

    I would also consider checking your egr valve.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors, http://www.gmtruckclub.com/forum/sho...5-GMC-Yukon-XL
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  9. #9

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    Quote Originally Posted by baumann6 View Post
    What is the proper fuel pressure for these trucks.
    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. #10

    Default

    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.

    1982 Chevrolet K10 Scottsdale
    5.0 Liter 350 Short Block
    Automatic/4WD35-Inch Tires
    15-Inch Micky Thompsons / 6 Inch Suspension Lift

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