"need help" 68 gmc

[tack driver]

Okay guys I need help with my 68 GMC. When I turn the key to start the truck it runs but when I let go of the key to the run position it dies. What can this be??? It ran fine before then started doing this now and then and now it will not run less I keep the key in the start position. Thank you in advance

[geezer#99]

Points or hei distributor?

[tack driver]

Its hei

[geezer#99]

Gotta be the ignition switch then!
You got a dedicated 12 v to that hei?

[tack driver]

I will check tomorrow

[GMC-YA68]

Originally Posted by geezer#99

Gotta be the ignition switch then!
You got a dedicated 12 v to that hei?

+1

Trace the HEI power and let us know how it's wired.

[tack driver]

I will do that that. Thanks guys I will let you know tomorrow its really cold where I'm at right now.

[57taskforce]

Farmington huh???? Howdy from Kirtland... I too am willing to bet on the ignition switch

[69chevy lwb]

Reason it runs when it's in start position is there is a jumper wire from the starter to the coil to provide a "hot start" of 12v on a points setup. When switched to hei it wasn't eliminated. Check the power along the key on hot to figure out the problem.

[70STOVEBOLT]

Originally Posted by 69chevy lwb

Reason it runs when it's in start position is there is a jumper wire from the starter to the coil to provide a "hot start" of 12v on a points setup. When switched to hei it wasn't eliminated. Check the power along the key on hot to figure out the problem.

If a dedicated hot 12V source was added for the HEI this would not make a difference. Sounds like it worked fine for a while. My bet is the ignition switch as well.

[69chevy lwb]

Well if the dedicated 12v key on hot somehow became broken or disconnected it would. It's worth checking the wire for power at both ends of nothing is coming out of the ign switch then it's bad. If that was the case it's likely other components would not be working suddenly as well.

[tack driver]

Thank you guys for all the info. After work today I will be checking what you guys asked me to.

[70STOVEBOLT]

Originally Posted by 69chevy lwb

Well if the dedicated 12v key on hot somehow became broken or disconnected it would. It's worth checking the wire for power at both ends of nothing is coming out of the ign switch then it's bad. If that was the case it's likely other components would not be working suddenly as well.

After re-reading your post, I agree with you. I misread it the first time.

[michael bustamante]

farmington huh, heck yeah its cold there, I hunted 2b last year, big buck but i froze!!!
let us know what you find

[tack driver]

Okay so I changed the ignition switch and also the tumbeler. Its doing the same thing as before. The power wire for the distributer is coming off the small post on the starter.

[70STOVEBOLT]

What color is it? For the HEI you need to run at least a 12 gauge wire and it should be dedicated. Most guys run their power directly from one of the IGN unfused terminals at the fuse box.

[69chevy lwb]

Okay then you need a key on hot to the hei. Get out the test light and find one under the dash. It should light up with the key on and shut off with the key off. Once you have located one find a place to tie into it and then run that wire to the positive side of the coil. There might also be an open terminal on the fuse block that's key on hot. That's my preferred method.

[tack driver]

Okay guys with a test light key off in the back of the ignition switch there is power ing post and no power on the pos pos. Key to the run position there is power to both ing and pos. So with that said it should run but it don't.

[tack driver]

Okay so now the wire going from the distributor to the small post on the starter. I put a jumper wire straight from the battery to that same wire and it runs just fine. Why would it run one day just like it is and not now? The wire is just fine, but ran derect to the battery its it runs good. I dont get it.

[69chevy lwb]

Sounds like you need to run a new ign wire then. Eliminate the one to the starter as that's only necessary for points ignition. Run it from the positive side of the coil to a terminal on the fuse block that's key on hot. That will take care of the issue.

[tack driver]

Just did it and runs good now. Thank you everyone!