Why doesn't my 1994 GMC 1500 C/K start? Cranks over fine. Starts sometimes but is random.

Hello Jeff, Thanks for the video but the ignition switch failure on the S-10 was not an "intermittent" problem but a consistent "cranks but no start condition" Hello Jeff, Thanks for the video but the ignition switch failure on the S-10 was not an "intermittent" problem but a consistent "cranks but no start condition"

That's ok , have seen intermittent problems with gm ignition switches ! I just couldn't find a video for one , I know there are videos on youtube with intermittent no starts because of ignition switch . I work at a Chevy dealer going on 15 years . We have had a lot of problems with ignition switches . But anyway I only sent you the video for viewing testing procedures. I could also suggest you check out videos on voltage drop testing , basic electrical trouble shooting etc... Not trying be a wise acker ,just trying to help . That's ok , have seen intermittent problems with gm ignition switches ! I just couldn't find a video for one , I know there are videos on youtube with intermittent no starts because of ignition switch . I work at a Chevy dealer going on 15 years . We have had a lot of problems with ignition switches . But anyway I only sent you the video for viewing testing procedures. I could also suggest you check out videos on voltage drop testing , basic electrical trouble shooting etc... Not trying be a wise acker ,just trying to help .

You mite also look at ignition system wiring diagram athttp://bbbind.com/free_tsb.html Test for lose connections , proper voltages ,all while wiggling wire harness to see voltage drops out . Or lose a ground . You mite also look at ignition system wiring diagram at http://bbbind.com/free_tsb.html Test for lose connections , proper voltages ,all while wiggling wire harness to see voltage drops out . Or lose a ground .

https://youtu.be/n1-lb13l45I ,here is an intermittent no start ,ignition switch . https://youtu.be/n1-lb13l45I ,here is an intermittent no start ,ignition switch .

Thanks Jeff..no worries about being a "wise acker" I appreciate your input. These intermittent problems are a real pain. I've read dozens of posts concerning these symptoms:

Warm or cold start.
My 1994 GMC 1500 4 WD 5.7L / Throttle Body injection.

Engine always cranks over. Most of the time it starts.

This morning this is what I did.

1/ Engine turns over fine and starts.
2/ Put an HEI spark tester on the coil to distributor lead...good spark.
3/ Put the HEI spark tester on the distributor cap lead posts...good spark on all cap positions.
4/ Probed coil (with LED test light) coil white to distributor for switching signal...signal present.
5/ Probed the pick up coil connector in distributor (With multi meter set to AC)signal present.
6/ Cracked fuel feed line at base of throttle body..good fuel supply.

So all looks good of course, its running, except for when I drive it for a while and it fails to start...lol

Here's what I've done in the past couple of weeks..

1/ Checked all connectors and grounds.
2/ Replaced the ignition switch located on the steering column.
3/ Scratched my head and wondered about a possible intermittent failure of an ignition component or fuel relay. I always thought that electronic components either worked or were fried. Good or bad but never intermittent.
I'm starting to wonder about that assumption.

I really hate troubleshooting by parts replacement, an expensive and often unproductive way to attempt repairs.. but with that being said... I'll have to wait for the no start intermittent to show up again and repeat the tests when the vehicle will not fire up. Test tools are in the truck cab..I'll post as soon as I resolve this frustrating intermittent. Thanks again for your help...much appreciated.

PS: When the truck fails to fire up…I can push start it (manual 4WD ) without fail. Go figure? Thanks Jeff..no worries about being a "wise acker" I appreciate your input. These intermittent problems are a real pain. I've read dozens of posts concerning these symptoms: Warm or cold start. My 1994 GMC 1500 4 WD 5.7L / Throttle Body injection. Engine always cranks over. Most of the time it starts. This morning this is what I did. 1/ Engine turns over fine and starts. 2/ Put an HEI spark tester on the coil to distributor lead...good spark. 3/ Put the HEI spark tester on the distributor cap lead posts...good spark on all cap positions. 4/ Probed coil (with LED test light) coil white to distributor for switching signal...signal present. 5/ Probed the pick up coil connector in distributor (With multi meter set to AC)signal present. 6/ Cracked fuel feed line at base of throttle body..good fuel supply. So all looks good of course, its running, except for when I drive it for a while and it fails to start...lol Here's what I've done in the past couple of weeks.. 1/ Checked all connectors and grounds. 2/ Replaced the ignition switch located on the steering column. 3/ Scratched my head and wondered about a possible intermittent failure of an ignition component or fuel relay. I always thought that electronic components either worked or were fried. Good or bad but never intermittent. I'm starting to wonder about that assumption. I really hate troubleshooting by parts replacement, an expensive and often unproductive way to attempt repairs.. but with that being said... I'll have to wait for the no start intermittent to show up again and repeat the tests when the vehicle will not fire up. Test tools are in the truck cab..I'll post as soon as I resolve this frustrating intermittent. Thanks again for your help...much appreciated. PS: When the truck fails to fire up…I can push start it (manual 4WD ) without fail. Go figure?