73-87 Chevy _ GMC Trucks > Electrical
no power to distributor
bd:
Speaking as a retired professional, I think you are applying bad judgment. Did you look at the wiring diagram I linked? It includes a schematic diagram of the bulkhead connector that shows which wire cavity the 12-gauge pink wire (Ckt 3) to the distributor uses to feed through the firewall.
Your decision to run a 14-gauge wire to feed the distributor from the 15-amp protected fusebox tap is inviting trouble that includes randomly blowing the fuse, overheating the distributor feed wire, and possibly limiting the ignition system to less-than-optimum performance. Regarding that distributor feed wire gauge, 12-gauge is adequate and factory for your 1978 K20, although 10-gauge is optimum and the gauge used in later years of production. It is alright to power the electric choke from that IGN tap, although I recommend that the choke wire passes through a two-prong oil pressure switch for the best drivability. But the original OEM distributor feed wire is protected strictly by a fusible link, not a readily replaceable fuse. The reason is that the fusible link is equivalent to an ultra-slow-blow fuse rated at perhaps 35-40 amps. How does the 15-amp fast-blow fuse in the fusebox compare?
The fact that all of the fuses and power taps in the fusebox are 'hot' with the ignition switched ON is a telltale that power delivery through the ignition switch is complete at least to the fusebox and probably to the bulkhead connector. The only real question that you need to sort out is whether power is flowing through the bulkhead connector into the engine compartment. If the appropriate bulkhead connector cavity is 'hot' in the engine compartment, the next questions are whether a 12-gauge wire occupies that cavity, and then where does it go from there? Not a difficult process, if a little tedious.
Make sure that the battery cable connection to the starter solenoid is suitably tight and that the attached fusible link does not stretch if tugged. Check the fusible link at the firewall junction block with a similar tug. Then use your test light to probe the appropriate cavity of the firewall bulkhead connector, using the linked wiring diagram as your guide. Bear in mind that original wire colors will degrade and can change significantly over time. So don't be too surprised if the original pink wire appears white or purple or orange or brown or red where it has been exposed to underhood heat, chemicals, and petroleum lubricants.
Don't shortchange yourself. Sort it out properly.
TheBigHat:
Thank you, I have been waiting for your reply. I was able to probe the inline fuse that resides on the solenoid and get light. One wire has a hard case fuse and the other does not. They both have power. If I knew all the answers there'd be no post asking someone for help - that you're offering, thank you. I think I'll.make the time today to get to the junkyard to find a replacement for the two studded distribution block the so-called auto-electrician destroyed for me. You are talking about the block located above the power booster? I found two fusible links there, one still good, the other contained a 23v glass fuse that was blown. I replaced the blown fuse and nothing changed. So I checked the fuse to see if it instantly blew. It did not, however the wire crumbled off at the crimp. So, I alligator clipped the ends together to see if anything would change. Nothing seemed to change. I would.much rather find the problem and repair it correctly. I need to get where I'm going.in the meantime. So, your.help is very appreciated.
bd:
You are welcome to any assistance I can offer.
The two-stud firewall junction block is imaged at the very bottom of this post.
A fusible link is not the same as a cartridge fuse...
A fusible link is a 6" length of highly specialized wire located at the "hot" end (the end of the wire closest to the power source) of a high-current feed wire. When a fusible link fails, it will sever (melt) like a normal fuse, but the encasing insulation may visually appear intact, distorted, or split. Because the wire is severed, if tugged, a failed fusible link will stretch like a rubber band or pull completely apart. Hence the instruction to "test" links by giving them a firm tug. You can find more information on fusible links in, Fuses and Circuit Protection.
The inline glass fuse that you found melted should be rated at 20 amps; it feeds the HVAC high blower through the blower relay. It has no bearing on anything other than the high blower function when the fan speed is switched to high. FYI - At some future point in your project, I would replace that inline glass fuse holder and fuse with a Mini-ANL 20. The OE plastic inline fuse holders used by the factory have a propensity to melt and distort resulting in poor high blower performance.
Rest assured that help is available for you to sort this out as long as you are attentive, persistent, willing to follow directions, and exhibit patience. Reread through what has been posted to date to wrap your arms around how the system is wired from the factory. Refer to the factory wiring diagram often and grow accustomed to using it. Ask questions about anything you don't understand clearly. And, don't cut corners. Diligence will get you where you want to be.
TheBigHat:
Wow, thank you! I just got back from the junkyard, I picked up a new junction block and took the harness from the bulkhead back to the starter. I was having trouble following the diagram honestly. But with a whole junk harness to probe and follow along with the diagram I hope to hone my skills. I'll get the band-aid off her soon hopefully! Thank you very much, glad to be a part of this forum!
JohnnyPopper:
bd your green truck needs a bath...jus sayin ;D
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