Chevy S10 sputters above 50mph

chevrolet
s-10

#1

Vehicle: 2003 Chevy S10 Pickup V6, w/61000 miles.



Recently I took my truck in for repairs and over the last two weeks I’ve had nothing but more problems. First diagnosis was dead battery which was replaced. Then a “severe” leak in the oil pain, which required a costly (almost all labor) gasket replacement. Then the car turned over fine but still wouldn’t start. That led to a fuel filter and fuel pump replacement.



Now only a few days later I have yet another problem. The truck started sputtering when I give it gas, roughly at 50mph or faster. I can’t really hear anything different at that speed, but there’s a lot of road noise in a truck. What’s most evident is a stop and go feeling when I press the accelerator at that speed, sometimes pretty severe like the car isn’t going to go, and other times much more subtle. If I accelerate, even hard, below that speed, I can’t really get the same symptom. Yesterday I did seem to get a bit of a sputter at idle, when it was cold, but this problem is definitely reproducible at 50mph or faster, although it’s not yet at the point where it’s happening 100% of the time, maybe 80% of the time. Doesn’t seem to make a difference if the engine is hot or cold.



My first concern is that it could be something I just paid to have replaced such as the fuel pump or fuel filter. I don’t want to take it back to the same shop, since it seems like I just keep leaving the shop with new problems, but if it’s something they did wrong, I’d push until they fixed it at no cost since their work is under warranty. I thought it could be something simple like the air filter and am contemplating trying that first, but I don’t want to cause damage or have more serious problems by waiting and not getting the problem fixed. Any suggestions and/or other things I can do to help diagnose the problem? Other possibilities I thought of include the catalytic converter (no engine light comes on and there’s no smell), or possibly spark plugs. I just feel like I’m really getting taken every time I bring this car in, as I had no problems whatsoever over the first 61K, and I’ve just spent $2000 and it’s running worse than when I took it in! I’d like to have some idea what to expect before I bring it in again.



Thanks,

Vern


#2

I would start by inspecting the spark plugs. Replace them if they’re overdue, along with the cap and rotor.
Next step would be replace the plug wires, ignition module and coil(s).
After that a compression test, but hopefully you don’t have to go that far.


#3

Sounds like a bad fuel pump. I would bring it back to the same shop. Maybe they picked up a defective replacement pump or kinked a fuel line while replacing it. Sounds like it’s their problem. You could probably connect a fuel pressure gauge and see if the pressure is within specs.