2002 silverado, 4.3 1500, "W" pickup is still a problem. A week ago it stopped dead in the driveway, never to start again. After much work I replaced the fuel pump and fuel filter.The truck started and ran for about 10 minutes, went to get a cup of coffee. Never ran again. I tried a number of things and finally determined that the spark appeared to be weak. Spark was yellow and often a faint twinkling light. Installed a new coil and she started right up. Ran strong,but then as it ran and started to warm up, it took a turn for the worst. It would be ideling fine, then all of a sudden the rpm would drop down to 500 and it would start to sputter then all of sudden take off running perfectly, as if there was never a problem. As I continued to let it run it would run perfectly for a few minutes then all of a sudden the rpm would drop off and in some cases stop. It will always restart. I would set in the cab and whenit would start to die I could some times feather the throttle and keep it running, in other cases a shot of fuel would allow the engine go up in rpms as it always has. In other attempts it would not take fuel or would at least no increase the rpms or level out. ANy one have any ideas? I have to get this runnig. I have to leave here shortly and the family needs the vehicle.
It has a new Delphi pump, new fuel filter, new coil. Fairly new distributor and rotor. I thought perhaps it was the throttle position sensor. Or idle air control? But keep in mind this problem is not only at idle it bogs down as you try and increase the rpms in some cases and is perfectly fine in others. How would a defective throttle Positon sensor act if it was going out? Your suggestions would be appreciated. I'm about 30 minutes from the closest AutoZOne, so I don't know if it throwing any codes. i don't think it will make it there.

Again, your thoughts would be greatly appreciated.

 

When my TPS went out in my 2001 5.3, I had to floor it to start it and when it started, it would idle around 2000 RPM's. When I put it in gear, it would drop down to 1000. Then I drove it and it would shift really fast. Even at WOT it would shift real early into the gears. It ran very rich. I installed new TPS and no problems since.

 

When this one starts, it starts and stays at 700-800 rpm then when it heats up it starts to range between 800 and 500rpm, sometimes it starts to cycle between 800 to 500. (up and down up and down)When in the low rpm range and you give it gas, some times it will come out of it and other-times it will fall flat it's face. I can not repeat it's operation, minute to minute. The only thing that is consistent is that I keep throwing money at it. Thanks

 

Just a thought. I have replaced many connectors going to the coil. Seen many wire breaks inside the insulation in that harness. With the truck running try moving the harness to the coil. Should be a pink and white wires. Sometimes I give them a good tug to find them. A pull to the coil and a pull towards the harness to the truck. Seen them break at the connector and back where the 2 wire harness goes into the main harness.