joshkruger

Hey guys I am a complete newby to the website. Thanks so much for keeping things up to date and making this available to people like me. Alright here are the details. I bought a 1991 K1500 Scottsdale about 4 weeks ago. The truck did fine for the first 3 weeks and then it started dying on me whenever the truck heated up a little (not over heat, just within peak performance heat). This also only happens when I drive on the interstate (60mph+). When I drive around town the truck does fine and there are no problems. The symptoms are: I will be driving down the interstate going exactly 65mph for about 5 minutes, then it feels like the fuel system starts cutting out. Almost as if there are bubbles in the line. I usually downshift to 4th (because the engine dies) and when I downshift the engine starts back up. When I keep the rpm high it runs fine for about 10 seconds and starts "hickuping" again. After about 1 minute of cutting out and kicking back in the engine cuts out one more time and the truck cannot be started for about 4-6 hours (until engine is cool again). I usually just leave the truck there and go back later that day. I have suspected the fuel pump and fuel filter but I have personally replaced both 2 days ago and it did it again this morning. Like I said, it does fine at 45mph but after that it is sure to cut out at one point or another.

Let me know if you guys have any more questions, I would appreciate any help.

Thanks,
Josh

jmack91z28

I'm guessing you've gota 350 motor? And i'm guessing you have a Throttle Body Injection System? And i'm also guessing you have a 5-speed manualtranny since you say you downshift into 4th on the interstate? Do you get a check engine light when the truck has problems? Have you checked some of the basics like the fuel pump relay? Have you checked fuel pressure, the ignition coil, ignition timing? How many miles are on the truck?

And to clear things up, it ONLY cuts out while going down the interstateAND at optimal operating temperature, correct? It does fine around town at city speed limits and while idling, correct?

What do you know about the trucks previous repairs besides what you have listed that you replaced?

And this probably doesn't matter, but what brand of spark plugs does the truck have?

joshkruger

For the most part you are correct. It is a 5 speed manual, it does have the Throttle Body Injection System, but I have a 305 motor in it NOT a 350. I do not get a check engine light when I am having problems. I have not checked any of the things you mentioned. The only things I have checked is spark plugs, spark plug wires, fuel pump (replaced), and fuel filter (replaced). There are 235xxx miles on the truck. And yes it only really cuts out when I am doing 55-60mph and up. AND it usually happens right when I reach about 180-190 (the guage is at about 1/3). And yes, if I get off of the interstate fast enough, I can drive it home by taking back roads (town and city speeds) but as soon as I get back on the Interstate it will cut out. I can drive all over town for a week at town and city speeds but I can't stay on the Interstate for more than 10 mins. and it cuts out. And then I have to wait for it to cool down (4-6hours) before it will start again. I don't know much else that has been replaced except the spark plug wires look new and I know the thermostat was replaced 6 months ago. Spark plug wires are some walmart brand.

Thanks,
Let me know any other questions,
Josh

rjsasaoka

Sounds like an issue I had with my '92 Silverado. After stopping off someplace, I would notice the temp gauge peg out and would have to wait a while till the engine cools down. At one time, the truck started to "stutter" when I took it on the highway, my friend thought it was the road but I told him it wasn't, it was the truck (if you drive long enough, you'll get the "feel" of your vehicle to know what is...)

I replaced the thermostat with a mid range (180 degree thermostat) and everything is just fine now. I also made sure I put in all the gaskets that it needed.

jmack91z28

Well first of all, if a chevrolet doesn't have ac delco spark plugs, it won't run right. Put in some basic Ac Delcos with about a .035 gap in them. I won't guarantee that'll fix it, but it sure would help.

There thermostat doesn't have anything to do with you cause your truck isn't overheating, right?

Spark plugsare about all I can think of right now, try that cause it's cheap as hell to replace, then we'll go from there.

rjsasaoka

He did mention that he had to let it sit for about 4 - 6 hours to cool down, I would be interested if the temp gauge has pegged out at the top when this does happen.

When I took my truck on the highway and started to pick up speed, it would "stutter" like I was running over grooves. It would have a hard time getting up to speed as if something was holding it back. Prior to this, I drove about 18 miles on the freeway and had stopped at a fast food place to get something to eat. I didn't notice it before going in, but after coming out and getting into the truck, it wouldn't start. I had electrical but the starter wouldn't crank. That's when I noticed at the time, the temp coming down from pegging out at the top.

Prior to this, I had my truck in the Chevy dealer and they suggested to replace the distributor, head gaskets, etc.. Well, after noticing the rise in temperature, I decided to try replacing the thermostat, which was about $10 or $12 and both the gaskets which were both under a dollar. Took my truck on a test drive and the temperature stayed at a constant temperature and I no longer had that "stutter" like I did before.

If anything else, the thermostat should be located at the front of the engine, easy to remove, replace and should only take about less than 15 minutes to replace. I would imagine if it were a spark plug issue, the truck would be running rough all the time, wouldn't it? The main piece of information is what is showing on the temp gauge when the truck fails to start.

One other suggestion is that the distributor is not advancing properly or the engine maybe running too cool... I would focus on the thermostat and maybe the distributor.

northey87