86 K20 4x4 350 Holly Carb - Crank, No Start

[viaminveniam1939]

Hi Everyone -

1986 Chevy K20 5.7L 350 3-Speed 4x4 Manual Holly Carb

Truck was idling for about 7 mins, then suddenly shut off. She cranks, but will not light.

- Thought I might have run out of fuel (currently swapping out 1 or 2 tanks).
- I added fuel and then changed the inline (aftermarket) fuel filter (planned to do regardless).
- I popped the fuel line off and observed fuel being pumped out (manual fuel filter seemingly not the problem, though still could be I suppose). Fuel pump, based on the appearance of the gasket/seal, looks newer (can’t say for sure tho).
- Battery is good/charged.
- Have noticed that the ignition (key), turn signal indicator act as if they are “gummed up” (not crisp, if this makes sense). Replacements are in the mail. NOTE: once -only one time did this occur- during my initial efforts to restart the truck after she shut down, I noticed that turning the key to start produced NOTHING (no lights, no starter, etc.).

UPDATE (03/05 @ 20:45 est):
1) turn signals & brake lights are NOT working.

Because I lack a solid understanding of automotive systems and the relationships they have amongst each other… What are the next most logical diagnostics steps to take?

Thank you
Nick

 

[bucket]

Check for spark. You can get a cheap inline spark tester from a local parts store that will almost make it fool-proof to check for spark. You may need a helper to turn the key though.

 

[viaminveniam1939]

Will do, thank you! fyi—checked the rear lights and turn signals and they are NOT working.

 

[RustyPile]

Light failure and no start condition probably not related.. With any light failure, the first thing to check is fuses.. Simple fuse replacement will not cure the problem. The cause of the fuse blowing is due to excessive current flow.. Number one cause for this is a short in the circuit..

Adding to Bucket's suggestion.. If you find you have no spark, the number one cause (but not the ONLY cause) of this is ignition module failure.

 

[RacingTurtles]

Will do, thank you! fyi—checked the rear lights and turn signals and they are NOT working.

Hey there, any luck?

I am experiencing a similar issue with your shutoff and no restart.
See my thread on the description of the problem in greater detail, but in short:
I was driving and then it shutoff on me. Took several tries to crank it and restart.
Then at home I started it and let it idle, it shuts off around 3-5 mins.

My thread in case you want to read and compare issues.

Vehicle shutoff while driving

Last night on 4/4/24 I addressed another looming concern. This "terminal block" seems to have been done by one of the owners. It was a piece of wood somehow connected to a piece of rubber with studs going through it. Seeing the wood with burn marks on it scared the crap out of me and I never...

www.gmsquarebody.com

I have not solved my issue yet. Things point to something related to ignition.
---


The turn signals and brake likes might be a separate issue.

Here's the factory service manual for your truck.

http://www.73-87chevytrucks.com/techinfo/7387CKMans/Service/X8632_1986_GMC_Light_Duty_Truck_CK_G_P_10_to_30_Service_Manual.pdf

It should have wiring diagrams, trouble diagnosis, and flowcharts on how you can fix the problem.
I may read through it later, mine is a 1990 with the TBI, but maybe it is the distributor or whatever.

 

[viaminveniam1939]

RacingTurtles - sorry for the slow reply! My shutoff, no restart issue ended up being the Ignition Control Module (HEI Distributor). This video was helpful for me:

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Also, u may wish to check what I believe is the Ignition Switch (attached to steering column, inside cab, behind steering wheel. Check this video out:

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Either way, replacing fuse block was obviously a wise/safe move on your part!

Thank u for manual link!

Keep us all posted.

 

[Matt69olds]

Read this:

https://www.gmcmi.com/wp-content/uploads/2014/05/HEI-Testing.pdf

 

[viaminveniam1939]

Read this:

https://www.gmcmi.com/wp-content/uploads/2014/05/HEI-Testing.pdf

This is great! Thank u for sharing.