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  1. #1

    Default 95 Yukon Low Power and Poor Gas Mileage

    Hi all,

    I bought a 95 Yukon that is a pig.

    I typically get 12.5 mpg...is that normal for city/hwy driving? I can get 14.5 if I do nothing but highway driving.

    It feels like it's pulling a load when I am going up a grade on the highway, and I really have to get into it to keep it at the same speed.

    Also, when I am driving around town, I can feel a significant improvement in power as soon as I pass 22-2300 RPM....it's like someone turns on a switch that increases the power output.

    I had a 99 Tahoe that had lots more power than this, and much better mileage. Unfortunately, the Tahoe was a lemon. I hope this isn't just a pig of a truck, because I want to be able to tow a race car a couple times a year.

    Things I have already done:
    - MAP sensor
    - Plugs
    - Wires
    - Dist cap/rotor
    - air filter
    - PCV valve, etc...all the regular tune up items
    - Fuel filter
    - Pulled all my hair out

    Thanks for any suggestions/replies!
    Adam Martin
    1971 Buick Centurion Formal Coupe
    1958 Buick Limited Four Door Riviera
    1995 GMC Yukon Four Door 4WD

  2. #2
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    stephan's Avatar
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    No worries Smartin, as long as it doesn't have a blue oval on the hood with "ford" written on it, it's not a pig. It looks like you've covered most of the tune up stuff.
    The only things I can think of are maybe the brakes dragging a bit, or possibly 4wd engaged? I know it sounds unlikely but since you just bought it, & possibly your family isn't familiar with it yet, maybe somebody could have leaned on it & not realized it, & the 4wd light could be burned out, & with a burned out 4wd light it could be an issue like below:

    http://www.gmtruckclub.com/forum/sho...-4-wheel-drive
    i have a 2001 chevy silverado 4x4 with the np2 transfer case that has the manual shift lever on the floor. i just replaced the transmission and the other day i was driving down the road and the 4 wheel drive light came on and transfer case started trying to put itself into 4 wheel drive. i couldn't get the light to go off so i crawled underneath and pulled a plug off the top side very back of the transfer case, what looked like a sensor and the light went off but the truck feels like its being held back when you drive it. whats causing it to shift itself into 4 wheel drive
    Last edited by stephan; 11-29-2010 at 10:55 PM.
    1988 Chevy C-3500 2wd (no pic)
    350 c.i. 5.7 L Stock Block, 4 Bolt Mains
    L-31 Vortec Heads, Edelbrock Cam & Intake,
    Holley 650, Flowtech Headers, Magnaflow exh.
    Jet Trans 700R4, B&M Ratchet, 4:10 gears,
    3" susp. lift kit "shadetree"
    No rev limiter, No speed limiter lol


  3. #3
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    murdog94's Avatar
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    You have the 5.7L TBI motor, 14.5-15mpg highway is right in the ball park, and the 12.5 combined is about right ive had 4 of the same engines and 12.5 was what i got on a good day with 2 of them. The 350TBI motor made 50HP or so less than the Vortec in your 99tahoe, so you are feeling the loss in power. I would do a fuel pressure test just be sure (should be 13PSI MIN) and try a Seafom cleaning (there are a bunch of threads here on the site)
    BUt as i said the 350TBI isnt as powerful as the Vortec but will do just fine pulling a trailer (i was towing a 26Ft enclosed that weighed in at just under 6K Lbs unloaded with my 1988... It isnt going to run nearly as fast as you might want but it will get you there..
    Oh and the 350TBI will RUN FOR 300K miles with out a hickup if properly cared for!! I personally love the 350TBI over the 350 Vortec. Just a better motor with less issues.
    Mike

    Currently

    1997 Chevy S-10 Blazer 4X4 with 330K miles and counting (Hunting rig).

    2009 Saturn Aura XE (wifes car)

    2011 F-150 Crew 4X4

    "Hold it to the floor till you see God.... Then Brake!!!!"

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