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1986 Chevrolet c10 8cylinder 350 Crank/no start
01-05-2016, 12:02 AM
Post: #1
1986 Chevrolet c10 8cylinder 350 Crank/no start
My Chevy C10 will start sometimes and then it wont for about 2weeks and then it will again. I have properly replaced the Distributor cap and Coil plus the ignition switch. I believe it is a intermittent spark problem. I do not think it is a fuel problem because it can flood and after the truck stops it will show signs of gas. Once the truck does start after about 5minutes it quits. What should I check for or replace next?


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1986 Chevrolet Truck C10 1/2 ton P/U 2WD 5.0L 4Barrel Carburetor OHV 8cyl 350engine
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01-05-2016, 06:53 AM
Post: #2
RE: 1986 Chevrolet c10 8cylinder 350 Crank/no start
Wow, a carburetor. I haven't messed with one of those in years. The last one I did mess with was a Chevy truck doing almost the same thing. I found 2 problems with it. First was a massive vacuum leak. So I would suggest checking all of the vacuum lines, intake, and brake booster if it has one. The other thing was the weights in the distributor were frozen up. We broke them loose, oiled them, and it ran pretty good so we then just replaced the springs and bushings. You can get a "Advance Curve Kit" fairly inexpensive at most parts stores that contain the parts you will need.

Other than that you may have to just start checking items like the timing, compression, plugs, wires, etc. Make sure the choke is closing and then opening at the proper times. When it dies, check to see if it has spark at the plugs. If it does, you know that you need to look for something else. If there's no spark it could be the module in the bottom of the distributor. That's probably where you want to start though. Does it or does it not have spark when it dies? Once you know that you will know which direction to go.

I hope that helps. Let us know what you find.

Thanks for using the forum,
Garner

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01-05-2016, 11:35 AM
Post: #3
RE: 1986 Chevrolet c10 8cylinder 350 Crank/no start
As Garner suggested, that module in the bottom of the distributor would be suspect if you are sure the spark goes away. That can be replaced by itself if you are careful and it will save you a few bucks. OTOH, many aftermarket companies offer a complete dist as a rebuilt unit for under $100 and that will save you the hassle of all those small parts and fooling with worn weights / springs for the advance plus the possibility of the flex wires on the pick-up coil being bad. http://www.rockauto.com shows several listings in either Cardone or AC Delco as a complete unit (Delco just over $100) that even come with the vac advance unit installed. Be sure to have your VIN handy as they used a few variations in that era and you will need it to get the right one.

BTW, just due to the age I would lean toward a complete dist as a unit because it will have new shaft bushings as well.
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01-05-2016, 05:16 PM
Post: #4
RE: 1986 Chevrolet c10 8cylinder 350 Crank/no start
Thanx for the help! I am worried that getting into the carburetor could get very technical and I've never done it so is it worth me trying or just hauling it to a mechanic to be safe.
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01-05-2016, 05:34 PM
Post: #5
RE: 1986 Chevrolet c10 8cylinder 350 Crank/no start
That depends on your ability level. If you are able to properly diagnose the lack of spark when the problem happens and have the know-how to replace the distributor, then why not do it yourself?

As for hauling it to a mechanic, if you do that be sure to ask if the guy has a working timing light. This is a "must have" tool to do the job right and very few guys have one that still works. (including myself) It's something nobody uses unless they work on cars that are over 20 years old.

On a possible carb issue, they generally wont make an engine die after 5-10 minutes. Most likely you will have to wait and see if it's running better once the ignition problem is ironed out.
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01-05-2016, 05:48 PM (This post was last modified: 01-05-2016 05:58 PM by dylansmothers556.)
Post: #6
RE: 1986 Chevrolet c10 8cylinder 350 Crank/no start
When you guys say module at the bottom of the distributor what exactly do you mean? As in, what do I search to find the part?
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01-05-2016, 06:57 PM
Post: #7
RE: 1986 Chevrolet c10 8cylinder 350 Crank/no start
That part would be the ignition module.... but in order for that to work the pick-up coil would also need to be good, (and they do go bad) which is why I was leaning toward using a whole remanufactured distributor. IOW, everything that normally wears out is already replaced so you have an entire unit with a warranty. Of course this is where you want to be sure to have a proper diagnosis first. No sense in throwing parts at a vehicle if that wont fix the issue.

I saw an entire distributor on that web site for under $60 in the Cardone brand, which makes quick work out of a repair compared to fooling with all the small parts yourself. The main difference here is I have the 45 years experience to test and narrow it down to the $15 part that most DIY types don't have. OTOH, my time is valuable so these days I would change the whole thing anyway just to make it easy on myself.
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01-05-2016, 07:50 PM
Post: #8
RE: 1986 Chevrolet c10 8cylinder 350 Crank/no start
Alright so to check and narrow down to this $60 part. What should I test to find out if this is it?
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01-05-2016, 08:57 PM
Post: #9
RE: 1986 Chevrolet c10 8cylinder 350 Crank/no start
You mentioned that you think the spark goes away even though you have replaced the ignition switch, the dist cap, and the coil, right? If the spark still goes away when it warms up then 99% chance the problem is within the distributor. Your job is to see if that's true next time it dies. As soon as it quits is when you check for spark. IOW, while it's still warm and the problem is happening.
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01-05-2016, 09:17 PM (This post was last modified: 01-05-2016 09:42 PM by dylansmothers556.)
Post: #10
RE: 1986 Chevrolet c10 8cylinder 350 Crank/no start
Alright I checked the spark after it ran and it went away so I believe it would be worth the try of replacing the distributor. My only question is when I do this would it mess up my timing? I know that this is changed by turning the distributor housing and the springs&bushings. I remember that you said I should check if the mechanic has a timing light. looked into the whole situation and how to set timing and how a timing light is used but I never found clearly if replacing the distributor would cause a timing problem to come to fruition.
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