96 K1500 bucks and sputters

My 96 K1500 4x4 has about 53000 miles, a 4.3l V6 and 5 speed. Around 27000 miles, I started having problems with the engine cutting out momentarily at
mid rpms, light load. Othre symptoms: - does not do it at all for the first 2-3 minutes after cold start. - seems to be worse in wet weather, but does it on dry days too - sometimes improves after driving for 20 minutes or so - will do it at a steady speed when rpms are around 2000 to 2500 - no misfires at idle or under heavy load - most pronounced when letting off the gas to shift, feels like the engine is cutting out, not just one cylinder, causing bucking. - overall, there is a slight lack of power, even when the engine seems to be running smoothly
When it first happened, the truck died and was hauled to the dealer who said the injectors were bad. I didn't buy that (also didn't have the $$$) and then got feedback from the newsgroup to change rotor and distributor cap. Engine ran well for a few thousand miles then it started again. I've now replaced these parts for the fourth time and, this time, there was not much improvement.
Other things I've done, related to this or not: - per TSB, rerouted coil wire to clear other metal parts - replaced coil and wires - replaced fuel pump - replaced cat convertor (bad ignition likely killed old one - common problem per TSB) - did a "mist" test suggested by newsgroup guru, spraying fine mist of water around hi voltage parts while engine running -> no corona observed.
Maybe unrelated... refilled cooling system and engine now runs cold (havne't replaced t-stat yet). Gauge reads about 150 when warm. Before, when coolant was low, gauge was closer to 200 and had wide temp swings. Bucking problem SEEMS to be worse with engine running cooler.
Thanks for any help!!My 96 K1500 4x4 has about 53000 miles, a 4.3l V6 and 5 speedd. Around 27000 miles, I started having problems with the engine cutting out momentarily at mid rpms, light load. Othre symptoms: - does not do it at all for the first 2-3 minutes after cold start. - seems to be worse in wet weather, but does it on dry days too - sometimes improves after driving for 20 minutes or so - will do it at a steady speed when rpms are around 2000 to 2500 - no misfires at idle or under heavy load - most pronounced when letting off the gas to shift, feels like the engine is cutting out, not just one cylinder, causing bucking. - overall, there is a slight lack of power, even when the engine seems to be running smoothly
When it first happened, the truck died and was hauled to the dealer who said the injectors were bad. I didn't buy that (also didn't have the $$$) and then got feedback from the newsgroup to change rotor and distributor cap. Engine ran well for a few thousand miles then it started again. I've now replaced these parts for the fourth time and, this time, there was not much improvement.
Other things I've done, related to this or not: - per TSB, rerouted coil wire to clear other metal parts - replaced coil and wires - replaced fuel pump - replaced cat convertor (bad ignition likely killed old one - common problem per TSB) - did a "mist" test suggested by newsgroup guru, spraying fine mist of water around hi voltage parts while engine running -> no corona observed.
Maybe unrelated... refilled cooling system and engine now runs cold (havne't replaced t-stat yet). Gauge reads about 150 when warm. Before, when coolant was low, gauge was closer to 200 and had wide temp swings. Bucking problem SEEMS to be worse with engine running cooler.
Thanks for any help!!My 96 K1500 4x4 has about 53000 miles, a 4.3l V6 and 5 speedd. Around 27000 miles, I started having problems with the engine cutting out momentarily at mid rpms, light load. Othre symptoms: - does not do it at all for the first 2-3 minutes after cold start. - seems to be worse in wet weather, but does it on dry days too - sometimes improves after driving for 20 minutes or so - will do it at a steady speed when rpms are around 2000 to 2500 - no misfires at idle or under heavy load - most pronounced when letting off the gas to shift, feels like the engine is cutting out, not just one cylinder, causing bucking. - overall, there is a slight lack of power, even when the engine seems to be running smoothly
When it first happened, the truck died and was hauled to the dealer who said the injectors were bad. I didn't buy that (also didn't have the $$$) and then got feedback from the newsgroup to change rotor and distributor cap. Engine ran well for a few thousand miles then it started again. I've now replaced these parts for the fourth time and, this time, there was not much improvement.
Other things I've done, related to this or not: - per TSB, rerouted coil wire to clear other metal parts - replaced coil and wires - replaced fuel pump - replaced cat convertor (bad ignition likely killed old one - common problem per TSB) - did a "mist" test suggested by newsgroup guru, spraying fine mist of water around hi voltage parts while engine running -> no corona observed.
Maybe unrelated... refilled cooling system and engine now runs cold (havne't replaced t-stat yet). Gauge reads about 150 when warm. Before, when coolant was low, gauge was closer to 200 and had wide temp swings. Bucking problem SEEMS to be worse with engine running cooler.
Thanks for any help!!
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Hi,
I've been having a very similar problem with my car, only difference is that mine seems to be much more random. I haven't had the opportunity to really go in and try to fix it yet, but I can give you some more suggestions that was given to me by the Audi newsgroup. You've all ready done a lot of what was suggested to me. Have you changed the fuel filter yet? The other thing to check (not even positive if your truck has one or not, but it makes sense that it would) is the fuel pressure regulator. Check your fuel lines, see if any have an unusual amount of rust/corrosion on them. If you can't do this easily at home and you don't have a regular mechanic you have a good relationship with, you can try out a local instant oil change place, sometimes, they will be nice enough to let you go bottomside and have a look (granted, if you aren't getting any services done, they may be less likely to be helpful. Make sure you wear oil resistant soled shoes, it can get a bit slippery down there.) Have you tried a complete fuel system treatment? I work at Valvoline Instant Oil Change so I am a bit biased towards their products. I used the complete treatment in my car, and it worked great, no bucking or hesitating for that tank of gas and half the next. It did come back, but at least I was able to narrow the problem down to the fuel system. There's also a 3 part cleaner that cleans the throttle body, intake, and fuel injectors, it's quite a bit more expensive, but, if it works... I haven't had this done on my car since it's a turbo, and it can't be used on turbos. Finally, I know a lot of rigs put a cover over the front grill of the truck during winter, so the engine can run warmer. I have no experience with this, perhaps there are other people out there that can advise on doing that.
Please keep me posted on the status. I'm going to be putting my car up for the winter so I can figure out and fix the problem I'm having. The problems are similar, so hopefully we can help each other out with the solution.
Enjoy Bill
1991 Audi 200TQ 1996 Chevy K1500 Z71

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96 K1500 bucks and sputters Group: alt.autos.4x4.chevy-trucks Date: Tue, Nov 11, 2003, 4:39pm (CST+6) From: snipped-for-privacy@stny.rr.com (RogerSeymour) My 96 K1500 4x4 has about 53000 miles, a 4.3l V6 and 5 speed. Around 27000 miles, I started having problems with the engine cutting out momentarily at mid rpms, light load. Othre symptoms: - does not do it at all for the first 2-3 minutes after cold start. - seems to be worse in wet weather, but does it on dry days too - sometimes improves after driving for 20 minutes or so - will do it at a steady speed when rpms are around 2000 to 2500 - no misfires at idle or under heavy load - most pronounced when letting off the gas to shift, feels like the engine is cutting out, not just one cylinder, causing bucking. - overall, there is a slight lack of power, even when the engine seems to be running smoothly When it first happened, the truck died and was hauled to the dealer who said the injectors were bad. I didn't buy that (also didn't have the $$$) and then got feedback from the newsgroup to change rotor and distributor cap. Engine ran well for a few thousand miles then it started again. I've now replaced these parts for the fourth time and, this time, there was not much improvement. Other things I've done, related to this or not: - per TSB, rerouted coil wire to clear other metal parts - replaced coil and wires - replaced fuel pump - replaced cat convertor (bad ignition likely killed old one - common problem per TSB) - did a "mist" test suggested by newsgroup guru, spraying fine mist of water around hi voltage parts while engine running -> no corona observed. Maybe unrelated... refilled cooling system and engine now runs cold (havne't replaced t-stat yet). Gauge reads about 150 when warm. Before, when coolant was low, gauge was closer to 200 and had wide temp swings. Bucking problem SEEMS to be worse with engine running cooler. Thanks for any help!!My 96 K1500 4x4 has about 53000 miles, a 4.3l V6 and 5 speedd. Around 27000 miles, I started having problems with the engine cutting out momentarily at mid rpms, light load. Othre symptoms: - does not do it at all for the first 2-3 minutes after cold start. - seems to be worse in wet weather, but does it on dry days too - sometimes improves after driving for 20 minutes or so - will do it at a steady speed when rpms are around 2000 to 2500 - no misfires at idle or under heavy load - most pronounced when letting off the gas to shift, feels like the engine is cutting out, not just one cylinder, causing bucking. - overall, there is a slight lack of power, even when the engine seems to be running smoothly When it first happened, the truck died and was hauled to the dealer who said the injectors were bad. I didn't buy that (also didn't have the $$$) and then got feedback from the newsgroup to change rotor and distributor cap. Engine ran well for a few thousand miles then it started again. I've now replaced these parts for the fourth time and, this time, there was not much improvement. Other things I've done, related to this or not: - per TSB, rerouted coil wire to clear other metal parts - replaced coil and wires - replaced fuel pump - replaced cat convertor (bad ignition likely killed old one - common problem per TSB) - did a "mist" test suggested by newsgroup guru, spraying fine mist of water around hi voltage parts while engine running -> no corona observed. Maybe unrelated... refilled cooling system and engine now runs cold (havne't replaced t-stat yet). Gauge reads about 150 when warm. Before, when coolant was low, gauge was closer to 200 and had wide temp swings. Bucking problem SEEMS to be worse with engine running cooler. Thanks for any help!!My 96 K1500 4x4 has about 53000 miles, a 4.3l V6 and 5 speedd. Around 27000 miles, I started having problems with the engine cutting out momentarily at mid rpms, light load. Othre symptoms: - does not do it at all for the first 2-3 minutes after cold start. - seems to be worse in wet weather, but does it on dry days too - sometimes improves after driving for 20 minutes or so - will do it at a steady speed when rpms are around 2000 to 2500 - no misfires at idle or under heavy load - most pronounced when letting off the gas to shift, feels like the engine is cutting out, not just one cylinder, causing bucking. - overall, there is a slight lack of power, even when the engine seems to be running smoothly When it first happened, the truck died and was hauled to the dealer who said the injectors were bad. I didn't buy that (also didn't have the $$$) and then got feedback from the newsgroup to change rotor and distributor cap. Engine ran well for a few thousand miles then it started again. I've now replaced these parts for the fourth time and, this time, there was not much improvement. Other things I've done, related to this or not: - per TSB, rerouted coil wire to clear other metal parts - replaced coil and wires - replaced fuel pump - replaced cat convertor (bad ignition likely killed old one - common problem per TSB) - did a "mist" test suggested by newsgroup guru, spraying fine mist of water around hi voltage parts while engine running -> no corona observed. Maybe unrelated... refilled cooling system and engine now runs cold (havne't replaced t-stat yet). Gauge reads about 150 when warm. Before, when coolant was low, gauge was closer to 200 and had wide temp swings. Bucking problem SEEMS to be worse with engine running cooler. Thanks for any help!!
Any codes? Steve C
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I had a similar "bucking" it turned out to be the pickup coil in the distributor. My bucking occured at medium throttle/low rpm. As in a medium throttle take off from a stop or medium throttle accelleration from 45mph (in OD). Checked it with a timing light, and there were false triggers alll over the place. Wound up replacing the distributer because the reluctor fell apart when I tried to dismantle it.
Good luck
Martin

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