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  1. #1

    Default 99 tahoe looses power pulling heavy loads uphills

    When I pull my utility trailer with a heavy load up steep hills the truck continues to lose power unless you keep your foot in it. It ends up shifting all the way to low. After I reach the top of the hill it has no power. I turn it off and something resets under the hood, it sounds like a door opens or closes, then it runs perfect until the next hill. I took it to a dealer in Casper WY and the replaced the fuel pump. This did not fix the problem ($784 later). It runs fine most of the time, but sometimes when I turn it off and restart it soon after shutting it off it hesitates for a while even without a heavy load. They said it had several codes like the MAP sensor, Cat back pressure but they all clear after you turn it off and then restart.

  2. #2
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    I'm not familiar with the sound you describe as a door opening, but this sure sounds like a fuel delivery problem. The fuel pump was a good shot because so many of them fail, but has anybody checked the fuel pressure regulator? Also if you can borrow a fp guage, hook it up & drive a steep hill with a load & see what the pressure does. It may be dropping like a rock.
    Plugged cats & exhausts can also cause lack of power & it's cumulative at higher speeds.
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  3. #3

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    Welcome to the G M T C ! I thing that Stephen is "right on" on your power problem and I'd bet on the cats.


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  4. #4

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    the dealer in Casper WY checked the whole exhaust system and said ther was no problems

  5. #5
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    What gears are in the truck? Did you change out the Gas Filter? Air Filter?
    08 Z71 Avalanche Mods to date: K&N CAI,Hellwig Swaybars and End Links, Corsa Sport Exhaust, Superchips Programer,IPCW LOF & 3rd brake light and tails, AMI Gas door,Show Hooks and Door locks, Enkei Wheels, with Pirelli tires, StreetScene Bowties, Grant Steering wheel,Muth signal mirrors,SSBC Big Brake kit,Huskyliner Mug gards,Floor mats and Hood shield, McGard Lug nuts and locks, Bedrug, Cervini's Ram Air hood,35watt HID Fog lights, Sylvania bulbs all around ZXE's Highs and Lows, WhiteNight Back up lights,Sirius and HD Radio, SnugTop sitting on deck now Got a Softopper on now,Tempress Boat Hatches.... New Bilstein shocks are on... New Mods coming soon..... X

  6. #6

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    The dealer replaced the fuel filter and it has a clean K&N air filter

    ---------- Post added at 01:53 PM ---------- Previous post was at 01:51 PM ----------

    The gears are whatevey came stock

    ---------- Post added at 01:54 PM ---------- Previous post was at 01:53 PM ----------

    what ever came stock

  7. #7
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    How did the dealer check the cats? What did they do?

  8. #8

    Default

    There is no sensor/code for Cat back pressure.

    Dump the K&N, go back to a paper filter. That is causing your MAF issue. Hopefully you can just clean the MAF rather than have to replace it.
    When you hear hoofbeats, look for horses not zebras.

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    *****thread moved here********
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    EGR valve. Have it checked.

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