96 chevy k2500 random no start
Thread Starter
CF Beginner
Joined: Oct 2022
Posts: 15
Likes: 1
From: Flagstaff, AZ
1) What is the general condition of the wiring?
2) Is the harness looming falling apart (just about crumbles to the touch of it’s old enough)?
3) Are any component connectors damaged (primarily missing retaining tab) and possibly not remaining seated?
4) Any known fixes from the past related to starting and driveability? (Less about who the repairman was and more about what was replaced and why.)
One more check to make, as sometimes the simplest things are overlooked:
The IAC valve.
At the moment, I don’t have time to list all the reasons why it could be causing the problem, but I did a write up on these a while back that explains how they work and how to test them.
Read all of it to know what tests to do.
I realize now I should probably edit it to better organize the info but as of now it’s as originally written.
https://chevroletforum.com/forum/198...urious-101819/
2) Is the harness looming falling apart (just about crumbles to the touch of it’s old enough)?
3) Are any component connectors damaged (primarily missing retaining tab) and possibly not remaining seated?
4) Any known fixes from the past related to starting and driveability? (Less about who the repairman was and more about what was replaced and why.)
One more check to make, as sometimes the simplest things are overlooked:
The IAC valve.
At the moment, I don’t have time to list all the reasons why it could be causing the problem, but I did a write up on these a while back that explains how they work and how to test them.
Read all of it to know what tests to do.
I realize now I should probably edit it to better organize the info but as of now it’s as originally written.
https://chevroletforum.com/forum/198...urious-101819/
CF Veteran
Joined: May 2011
Posts: 1,578
Likes: 302
From: Central Iowa
the wiring is in decent shape, over the years I've had an issue with the wire for the 4x4 resting on the manifold so that has been my only wiring issue since I've had the truck. Typical 26 yr old harness, a little crumbly near hot areas and oil soaked in the wires near the front pumpkin area from years of oil leaks. Seeing that I'm getting good fuel pressure and spark to all plugs and starter fluid won't start it my next idea I'm thinking is maybe the timing is off significantly?
Because you’ve stated that when the truck runs, it doesn’t have any driveability issues, I don’t think a mechanical timing issue is the cause, but here’s how to verify it:
Bring #1 (driver side front) to TDC compression stroke. Remove the distributor cap and see if the ignition rotor is pointing at the #1 contact position on the cap. It helps me to mark the distributor base with a sharpie.
The #1 contact point is not the same as the #1 plug wire connection. Note the “ridge” that’s molded into the cap at the #1 plug wire connection - the other end of that ridge is where the rotor should be pointing.
If the timing is good, and while the cap is off, manually turn the rotor back and forth to check for excessive play in the gear. It shouldn’t rotate more than about 5* or less.
Thread Starter
CF Beginner
Joined: Oct 2022
Posts: 15
Likes: 1
From: Flagstaff, AZ
Alright, update on the truck....went out this morning hopped I'm and it fired up instantly without any issues....last night messing with the spark plugs I accidentally swapped 2 wires so it had a slight misfire. Turned it off found the wires that were swapped turned it back on and no issues what so ever. Took it for a drive highway speeds etc. Truck has all the power and sounds great like nothing ever happened. Keep in mind last night before I went to bed the truck would not start and has not started since last Sunday. Could it be a computer issue?!?!? I'm absolutely lost now.
Thread Starter
CF Beginner
Joined: Oct 2022
Posts: 15
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From: Flagstaff, AZ
CF Veteran
Joined: May 2011
Posts: 1,578
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From: Central Iowa
If they’re chip keys, are they original or copies?
If copies, are they locksmith/dealer sourced, or cloned copies (hardware & Dept stores)?
I’ve come across some cloned keys that wouldn’t work unless the key is in a specific position relative to the lock cylinder because the chip in the head was positioned nearly out of range for the halo ring.
Thread Starter
CF Beginner
Joined: Oct 2022
Posts: 15
Likes: 1
From: Flagstaff, AZ
Do your keys have the resistor pellet in the shank? I can’t recall what year GM transitioned from the pellet keys to the chipped keys.
If they’re chip keys, are they original or copies?
If copies, are they locksmith/dealer sourced, or cloned copies (hardware & Dept stores)?
I’ve come across some cloned keys that wouldn’t work unless the key is in a specific position relative to the lock cylinder because the chip in the head was positioned nearly out of range for the halo ring.
If they’re chip keys, are they original or copies?
If copies, are they locksmith/dealer sourced, or cloned copies (hardware & Dept stores)?
I’ve come across some cloned keys that wouldn’t work unless the key is in a specific position relative to the lock cylinder because the chip in the head was positioned nearly out of range for the halo ring.
Thread Starter
CF Beginner
Joined: Oct 2022
Posts: 15
Likes: 1
From: Flagstaff, AZ
Just went out this morning to see if truck will start, no dice. Truck won't start with any of my 3 spare keys. I have to head to work so won't be able to start diagnosing again till tomorrow
CF Monarch
Joined: Jul 2011
Posts: 5,920
Likes: 139
From: kevinkpk
If it's the key, it should give you a security light, I'd suspect ignition switch, is the switch worn?
CF Monarch
Joined: Jul 2011
Posts: 5,920
Likes: 139
From: kevinkpk