Question about 1999 GMC Suburban

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Looses Power when on long trip pulling camper or trailer flagging oxygen Sensors error

I have a 99 GMC Suburban c1500 5.7 and last June it had a problem on a long trip while pulling a trailer in which it would begin to loose power and would not accelerate. I took it too the shop and they said it was the Oxygen Sensors Bank one and two and that my Catylitic converters needed to be replaced and then replace the Oxygen Sensors, it seemed to fix the problem for a while, now less than a year later I have the same code and problem. Drives fine around town, just when taking long trips and sometimes pulling a trailer, any help would be appreciated, thanks

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  • davertipton May 20, 2009

    Thanks for the reply, I didn't mention that I just did a full tune up, (Oil, plugs/wires, filters (gas filter as well) ). And it runs great around town with great pickup and smooth running engine. This only seems to happen when I get down the road pulling a trailer and start to hit some up hill areas???



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Sounds like a fuel problem. Change the filter and have the fuel pressure checked. A fuel problem can cause an O2 code.

Posted on May 19, 2009

  • Bennie Kennedy May 20, 2009

    Just for kicks, check the engen temp., and coolant level. over heating can cause power loss. If the rad is stopped up it may run cool in town but hotter on the road and under load causing a loss of power. Let the temp. get to normal and feel the tanks on the rad. from top to bottom. they should be the same temp. If the top fo the tank is hot and the bottom is cooler, sludge has setteled in the rad. and you only have 50% cooling.



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