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1997 chevy 1500 bad stumble??

l_maddog

By l_maddog
in Ask A GM Technician

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l_maddog New Member

l_maddog

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Ok so this is what I got from my observations, I have a 1997 chevy 1500 z71 350 vortec that hesitates,stumbles and bogs down when I apply the acclerator about 1/8 of the way down I notice this happens in any gear very badly when the speed ranges from 45 to 60, it almost feels like its bogging down and bout to die on me at those speeds, at take off If i were to stomp it i get a bad soot as if it is running to rich, and i mean the black smoke just rolls out of the tail pipes as if i were a diesel also around 60 and above if I were to back off the accelerator to about 1/8 throttle position it bucks and backfires like crazy.the motor was rebuilt 20,000 miles ago, ever since I rebuilt it, I drive it to and from camp Lejeune to my house in georgia which is 450 miles I notice also once I drive it that long it gets a lot worst, it however is more bearable to drive if I were to just toot around town for a short haul, on the highway above 70 it evens out jusr about tho till I back off the accelerator the stumbles come in every so often, I have not tried to tinker with it yet because for one I don't know where to start and another I don't have the money to just throw guesses at it, if I were to put a guess it would have to be ignition, it not burning off the fuel, but thts just an old fashioned breakdown, anybody who is experienced or knowledgeable on the help will be greatly appreciated

Doug_Scott Senior Enthusiast

Doug_Scott

Posted
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Are you not getting a check engine light? With that much black smoke it must be setting a code. If you want to try something, disconnect the vacuum advance from the distributor(assuming a 97 has a vacuum advance) and seeing if it makes any difference. If it seems to make it a lot better, check the wires connected to the pickup coil inside the distributor. This is the part that goes around the shaft at the base of the distributor inside the cap. It will have two wires connecting to the module. They have a problem with the two wires breaking due to the vacuum advance rotating the pick up coil and flexing the wires. Sometimes these wires will break and separate under vacuum advance, but will connect back up once the advance stops. If no vacuum line going to distributor, ignore all this.

l_maddog New Member

l_maddog

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Im pretty sure there isn't a vacuum advance on a 97 considering its throttle body and the timing once u set it to tdc on cylinder 1 the computer adjusts it from there, if all this shit runs me a headache like I have been seeing people dumping 100`s of dollars into a possible cause I'm just gonna ls swap it and call it a day because this problem has persisted for about 2 Years now and at first i was getting it was the tranny, and now its doing this with it being all the way from a sensor, to the whole Damn fuel injection system going out lol, rant over I guess

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