Wiring mystery

[evlblkrfl]

Hi guys. Im stumped...1977 K20.....just finished installing a new intake and carburetor went to start it up and I got nothing. No crank, no lights nothing. 12.4 volts at the battery the starter the alternator and the junction block by the brake booster. But.....when I run a jumper wire from the battery straight to the junction block everything works fine. Just strange though because the junction block already says it has 12.4 volts without the jumper wire, but without the jumper nothing works. 2 new fusable links already installed at the starter and the link right before the junction has continuity. Im definitely a newbie to electrical. Am I missing something??

 

[PrairieDrifter]

Did you plug the 12 volt supply (batt) into the correct spot on the distributor?

 

[evlblkrfl]

It is in the correct spot though I just tested it an it has no power. Even with my jumper wire hooked to the junction block

 

[PrairieDrifter]

It is in the correct spot though I just tested it an it has no power. Even with my jumper wire hooked to the junction block

It should be key on power only. To the distributor.

Did you mess with the junction block?

Did you get all the wires hooked up properly at the starter/replacement points?

 

[evlblkrfl]

Okay. I do get 12.1 volts at the battery terminal wire with key on AND my jumper wire. Still not understanding what's going on. Not even headlights will come on without my jumper. Im still measuring 12.4 at the terminal but nothings working unless I jump it. Every wire went back exactly where they got unplugged from. This is strange

 

[evlblkrfl]

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[evlblkrfl]

I thought for sure it was these fusable links at the starter. Nope

 

[evlblkrfl]

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[Dejure]

(1) A miss-wired distributor would not affect a starter and such.

(2) Too, keep in mind, having the correct voltage is not the same as having amperage. For example, you could be down to one strand of wire coming from your power source, get 12 volts, but not be able to move the current needed to fire plugs and such.

(3) A test bulb can, sometimes, be a better trouble shooting tool. It provides a load that demands power to function. On the other hand, a digital meter will read on a circuit with a fraction of a watt of power.

(4) As to the lack of any power, that's a good thing, kinda. In part, for the reasons stated, and because things like intermittent problems were the bane of electronics types.

(5) God only knows what was done to any given system over the decades since the truck rolled off the line. It's possible someone tapped something to get to point A from point B when they had a problem. Not necessarily likely, but possible.

(6) In the end, if all that went south (no power to anything, and lying readings (e.g., you have your 12 VDC)), it sounds like it's going to be something simple. Start, per item "2," above, with a check of battery connections. Then, double check every connection you made. That includes wires and connectors you disturbed (make sure they don't wiggle, etc., and watch that light mentioned above).

 

[evlblkrfl]

Yeah. I agree. Currently checking my grounds now. Body to engine to frame etc. Maybe I disturbed one somehow during the install....idk

 

[Turbo4whl]

Look close at your meter, when you test the block without your jumper, does the meter show -12.1 volts. Some meters, it is hard to see you are not reading positive voltage.

 

[evlblkrfl]

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[evlblkrfl]

Test light is as bright as can be without my jumper

 

[evlblkrfl]

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[CalSgt]

you’re missing the feed wires to the junction block

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