1985 Chevy C10 305: Engine Randomly Shuts Off

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

ortwein

Junior Member
Joined
Oct 27, 2016
Posts
2
Reaction score
0
Location
Mississippi
First Name
Mark
Truck Year
1985
Truck Model
C10
Engine Size
305
Hello All,

First, let me start by saying I am complete novice: I do most very simple repairs on my pickup (replaced a thermostat, water pump, simply plug-in-play stuff) but am extremely weak when it comes to diagnosing problems. The upshot is that I may ask stupid questions and require simplified responses. Bear with me...

So, here is my situation (It's lengthy).

I purchased ($1500) an old farm truck (1985 C10) to use primarily on my property, e.g., hauling feed and water, towing, and that sort of thing. On the whole I was quite pleased with the purchase. That said a month or two after taking ownership (this was in June or July of last year), I drove the pickup over to the neighboring town and noticed with was losing power, so I mashed the gas petal a few times and it gained power and I kept going (was driving around 50-55 mph). A few minutes later it happened again and once more I started mashing the petal keeping it going for 4-5 minutes before my leg started aching and I decided to pull over. Sure enough, as soon as I quit mashing the petal the truck died and I pulled over. The truck would not restart. I sat on the side of the highway for about 15 minutes trying to get it going--no dice. So I called a tow truck and had it delivered to my mechanic. When they arrived--to my chagrin--the truck started right up and the fellow drove my truck up the ramp and off he went.

A couple days later I inquired about the status of my pickup and was told that they started and let the truck idle multiple times with no issues. My mechanic thought it might have something to do with debris or water in the gas tank. The former owner of the truck claims the truck didn't "sit"--but who knows. So I drove the pickup home and resumed using it around the farm. No issues for a couple months and then it happened again. I managed to get it back to the house the next time. Again, after an hours or so, it started back up...this would happen once or twice every couple months or so. But I'd figured out how to deal with it.

Fast forward...

The truck had been running fine with no issues for several months when (August 2016) I needed to make a 90 mile drive to pick up a mattress we'd purchased in Memphis. By this time the motor had started leaking oil pretty significantly (had a small leak when I bought it). The trip to Memphis must have been too much for her because it really started losing oil once I arrived at my destination--to the point that every 15 miles or so I have to add more. Finally--she gave up the ghost. Long story short: I opted to have a new motor (refurbished) installed. Given the otherwise excellent condition of the truck, this seemed like a good choice at the time. Regardless, I also thought this would solve the mysterious issue outlined above.

It didn't.

Several days after getting the pickup home--it happened again about 1 mile from my home. I called the mechanic in Memphis who installed the motor and he sent a guy to pick it up. Of course, by this time the truck would start, but I still thought it a good idea for them to look at it because the truck was also idling really fast too, and "dieseled" when I turned it off. They made few adjustments to the carburetor and sent it back. (He also told me that if it happened again I might need to purchase a new carburetor.) I drove it for a week or so and it happened again. This time, however, it wouldn't restart at all. For a couple weeks I tried getting it running with starter spray...nada. Once more they drove 90 miles to the truck and this time replaced the entire distributor (previously they had only replaced the cap when replacing the motor). Back it came and--you guessed it: The problem still persists. I generally don't take it more than 10 miles from the house--which is difficult given where we live--for fear of it happening again. I would add, too, that this problem also happened during the winter.

I'm sorry this post is so long, but I thought details would help.

Thanks in advance...

Mark
I
 
Last edited:

1987 GMC Jimmy

Automobile Hoarder
Joined
Jan 23, 2016
Posts
5,848
Reaction score
2,387
Location
Mississippi
First Name
Jesse
Truck Year
1987
Truck Model
V1500 Jimmy
Engine Size
350
Damn. Well, welcome to the forum. I'm guessing you're around Grenada? If you were closer to Wesson/Brookhaven, I'd come by and help you. It's interesting that you replaced the motor and the distributor, and you're still having issues. What on the ignition system haven't you replaced? It may be good preventative maintenance to finish your ignition tuneup. Most of it looks like it's already done. I'd like to think it's a fuel issue. However, you said that you'd spray starting fluid, and it wouldn't even start. Did the new distributor at least cure this? What kind of carburetor is on it? If you could, try actuating the throttle after it's been run recently to see if you're getting two equal, consistent streams of gas down the primaries. The no start has Ignition Control Module written all over it, but you've replaced the dist., and it seems to have subsided anyways. The carburetor could just be tired (choke, accelerator pump, crud, etc.), the fuel pump could be going out, or you could have junk in the fuel system (did the mechanic take care of this?). What kinds of emissions stuff is still on it? EGR, AIR, etc.? It sounds like the carburetor may be ready for a rebuild/replace, and it sounds like the choke may be sticking, or things are not adjusted properly. The EGR valve can do stuff like this with the bogging and dying, and it has to me before. Vacuum leaks can cause a high idle, too. Just spitballing everything that comes to mind here.
 
Last edited:

Camar068

Supporting Member
Supporting Member
Joined
Feb 5, 2014
Posts
4,154
Reaction score
3,010
Location
Kentucky
First Name
David
Truck Year
1986
Truck Model
K10/LM7 5.3/4L60e/np208/3.73/32"
Engine Size
10 yrs Air Force
Check your grounds and the connector that hooks up to the dizzy and make sure they are all tight. I lost power and was stuck on side the road twice.

First time the connector was loose and wasn't making good contact. The only reason I jumped on the connector, the first time it happened, was I noticed it was loose fitting when I installed the engine....and forgot to fix it. While on side of the road, I pushed it back on and it fired right up.

Same thing happened a week after that. Turned out the dizzy was bad also. No issues since I replaced the dizzy. Just Throwing it out there. Was it a new dizzy they installed?

To test the EGR valve for a leak, I hook a syringe to the vacuum line directly to the EGR. Gently pull on the syringe, if the syringe doesn't want to go back in, it's leaking.

What really sticks out to me is that it seems to only do it when it's good and warmed up. Did you try starter fluid again to eliminate fuel? Maybe trace back the distributor wires and make sure they are good. When it won't start, check the voltage on it as well.

Oh yeh, just thought about it. Someone on here recently had an issue with the pins/blades inside the cap that go to the coil itself. If that were the case though, you would think your mechanic would have caught this when he changed the cap/dizzy.

Like 87, just rattling stuff off.

You must be registered for see images
 

Rusty Nail

Full Access Member
Joined
Jan 29, 2015
Posts
9,777
Reaction score
9,644
Location
the other side of the internet
First Name
Rusty
Truck Year
1977
Truck Model
C20
Engine Size
350sbc
I vote for a wire break inside the insulation of the distributor power wire. Likely the insulation has hardened at the bend before it plugs into the cap.
The break is there AND that explains why it waits till it warms up.
The wire relaxes and lengthens when warm, breaking connection. Contracts and kinks when cool, establishing connection
Sometimes but not always. I bet that wire is pretty rigid when the truck is cold? It has a pretty "tough" bend just under the cap, right?

Mark, you can buy a "replacement pigtail" damn near anywhere for 10 bucks.

Good luck, welcome to the forum.

*edit @Camar068 *
David I see what you did there, great minds think alike !
 
Last edited:

ortwein

Junior Member
Joined
Oct 27, 2016
Posts
2
Reaction score
0
Location
Mississippi
First Name
Mark
Truck Year
1985
Truck Model
C10
Engine Size
305
Wow! You guys are terrific. I need to read slowly through these suggestions and will report back ASAP. Again, thanks very much for the responses. Oh, and I'm in Water Valley, MS.

Best,

Mark
 

1987 GMC Jimmy

Automobile Hoarder
Joined
Jan 23, 2016
Posts
5,848
Reaction score
2,387
Location
Mississippi
First Name
Jesse
Truck Year
1987
Truck Model
V1500 Jimmy
Engine Size
350
Wow! You guys are terrific. I need to read slowly through these suggestions and will report back ASAP. Again, thanks very much for the responses. Oh, and I'm in Water Valley, MS.

Best,

Mark

Ahh, Water Valley. When I first got my Jimmy, the motor blew on the way home from Nashville in Batesville, and I'm an Ole Miss fan, myself. I've been to Oxford a good many times. It was actually between Ole Miss and Tulane in New Orleans for college, and I'm at Tulane. Good luck! Hope you get it fixed.
 

Forum statistics

Threads
42,070
Posts
908,404
Members
33,545
Latest member
GrayWK
Top