73-87 Chevy _ GMC Trucks > Electrical

no power to distributor

(1/3) > >>

I have a 78' K20 that is not getting 12v through the distributor wire. I haven't been able to figure out where that wire's source is. I did find a fuse link on the firewall right above the power booster in a bundled wire which had a blown fuse in it. I thought I may have found the problem. That turned into another problem because after I replaced it with what I thought was supposed to be a 32v fuse the truck still wouldn't start. I tried to check the fuse again to see if it may have instantly blown from a short somewhere, possibly the reason the fuse blew to begin with but the fuse wasn't blown. However the crusty fuse link did at that point break on the end. Now I don't know what that is for and still have no power to my distributor. I have headers and was able to probe both sides of the fusible link and got light on both sides. I put a jumper on the broken fuse link to see if that would work also, no luck. Now I have a broken fuse link I don't know what is to and no power to my distributor.

I've ruled out the ignition switch, that didn't fix it.

The factory wiring manual is your friend:  1978 Wiring Manual

Power routing to the distributor is fairly simple.  It runs from the starter solenoid 3/8" battery cable stud through a 6" long 14-Gauge fusible link and 10-Gauge red wire to the double-stud firewall junction block.  The two studs of the firewall junction block are jumpered together via a flat bus.  From the firewall junction block, power passes through a 16-gauge fusible link and 12-gauge red wire to the firewall bulkhead connector where it passes into the cab and a 6-way splice taped up inside the dash wiring harness.  From the taped splice, two of the six 12-gauge red wires route directly to the ignition switch, supplying power to the switch.  From the ignition switch, a 12-gauge pink wire runs back out through the firewall bulkhead connector to the distributor B+ terminal of the HEI distributor cap to power the ignition system.

Using an incandescent test light clipped to good clean grounds, do you find B+ power on both studs of the firewall junction block?  Do you find B+ on the STOP, TAIL and ACC fuses in the fusebox?  With the ignition switched ON, do you find power on the "CLSTR FEED" and "B/U LPS   DIR SIG" fuses?

Thanks for your reply, I'll be looking into all of that today. I took it to an "electric shop" yesterday and for some reason he felt compelled to completely remove my junction block and took a hand grinder to it. I think I will start at the junkyard getting another one of those, get it back to normal there and start over. I have ran it by hotwire and everything did seem to work though.

Everything on my fuse panel is hot except for pnl. I also probed every wire that looked like it could be pink there were about four or five and even an orange one they are all hot going into the back of the fuse panel. The spot that has no power at pnnl has a fuse that appears to not be blown. I'm considering just running a spatula connector to the distributor from the ignition side of the fuse block is there anything wrong with doing that?

I finally threw in the towel. I ran 14 gauge from the IGN tab on the fuse block to the distributor cap, then scotch spliced a section of 16 guage to the electric choke. It's not factory, but it's working. I see a harness replacement being added to my long term to do list. Now I have to figure out how to get power to my instrument panel lights. Were they on the same circuit as the ignition coil wire? Suspecting there's things on this truck that have been messed with in it's 43 years.


[0] Message Index

[#] Next page

Go to full version