My 350 engine stops and starts up again while driving. Sometimes it feels like it's running on 4 cylinders.

[ChevyMan94]

My 1994 K2500 350 V8 engine stops and starts up again while driving. Sometimes it feels like it's running on 4 cylinders, not always though. But it'll
stop and within a second or two start up again. It'll do this several times before running back to normal. I don't drive fast or hot rod the truck, either. It doesn't
matter if it's on cruise control or not.
I'm scared I'm going to ruin the engine if I don't resolve this issue fairly soon. Has 275,000 miles on it.
Well taken care of, though. Any ideas? Things I should check or bypass to ascertain the problem? I'm 81 but still fairly active. Thanks for any
comments or suggestions. Appreciate them all!

 

[SirRobyn0]

Wow, I mean that could be a lot of things from the carburetor flooding, or leaning out, or a coil or other ignition break down. If you are able to take some video (really doesn't matter if it's video I'd like to hear what it sounds like when it's acting up) So if you could get some video or audio of it acting up and up load it to youtube and link it to your thread here. It would really help us, but also understand if that is out of the question.

 

[squaredeal91]

If it consistently does the problem i would try unplugging coolant temp sensor and see if it acts better.

 

[SirRobyn0]

@squaredeal91 Thanks for saying that. All though I saw the vehicle year it just didn't click that he has a GMT-400, and I was busy seeing a carburetor in my head lol.

If the check engine light is on it would be very much worthwhile to pull the codes even if the only method you have is the connector jump and count the flashes..

 

[squaredeal91]

I was guessing tbi from signature pictures of truck. I'm still bad at navigating this site lol

 

[ChevyMan94]

Hi, Sorry I didn't mention it but yes, it's TBI. Can't really video or take a shot of what's happening because
first off it's all of a sudden....might happen in first mile...might happen after 50 miles. And actually there's nothing to see or hear
as it just stops running for a second or two, then starts up again. And other then the engine bucking for a split second before it starts up again, there's literally no noise associated with it. One time lately, though, when it was doing it several times in a row it was running like it wasn't running on all 8...don't really know if it was lacking gas or wasn't getting full spark but was definately struggling. Then, all of a sudden she's back to normal again. Really a stumper. Never have run across anything like this in my entire life.
i was wondering if a ground wire could possibly be the answer. Reason I say this is that I was stopped by police a few weeks ago for no brake lights. Never got a ticket but was told to get them fixed asap. Got home and found a ground wire back by the spare tire that didn't look too good. Took it off, ground don the metal until it was nice and shiny, did the same for the connector and bolted it back on again. Problem solved. Brake lights worked perfectly.

 

[SirRobyn0]

Hi, Sorry I didn't mention it but yes, it's TBI. Can't really video or take a shot of what's happening because
first off it's all of a sudden....might happen in first mile...might happen after 50 miles. And actually there's nothing to see or hear
as it just stops running for a second or two, then starts up again. And other then the engine bucking for a split second before it starts up again, there's literally no noise associated with it. One time lately, though, when it was doing it several times in a row it was running like it wasn't running on all 8...don't really know if it was lacking gas or wasn't getting full spark but was definately struggling. Then, all of a sudden she's back to normal again. Really a stumper. Never have run across anything like this in my entire life.
i was wondering if a ground wire could possibly be the answer. Reason I say this is that I was stopped by police a few weeks ago for no brake lights. Never got a ticket but was told to get them fixed asap. Got home and found a ground wire back by the spare tire that didn't look too good. Took it off, ground don the metal until it was nice and shiny, did the same for the connector and bolted it back on again. Problem solved. Brake lights worked perfectly.

I will say I've run into coil doing that. Also I have seen TPS sensors (and bad connections at the TPS) on the TBI systems causing stalling and bucking. As soon as you said bucking it made me think of those things. Never hurts to check grounds.

 

[squaredeal91]

Not sure if it's helpful or not, probably not your problem. But Yesterday I had to strap our 99 burban home 5 miles, it Died while cruising the highway. No start. Cranks like crazy sounding like it's getting a spark every so often. If it was carbureted I would say timing too advanced. Long story short after some tests I cleaned up an extra cap and rotor I had and put them on. started right up. I Never thought a cap or rotor would just stop working like this but it's possible. I hope you get yours figured out soon.