Question about 1991 GMC K2500

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1991 gmc med duty truck with 454 tbi ,backfires, no power.

Code 42 is set, once it warms up it backfires when under any load resulting in no power, when above 2000 rpm. If i shift up it will pull good until rpms come back up.could it be the module ? the cap , rotor, plugs & wires where replaced 9 months ago. i removed cap there was a lot of green corrosion on contacts so i cleaned it and re-installed it, maybe its shot ?

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By module do you mean computer? There's nothing wrong with it. Yea, replace all ignition components with new ones. New cap, rotor, wires and spark plugs.

Posted on May 18, 2009

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1 Answer

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