On my '87 carbureted 305, it's developed an electrical gremlin that I haven't been able to figure out. It's a sporadic problem. Most of the time, it'll start just fine, and then out of the blue, it shows up again.

Right now it's stuck at work because it won't start. Battery voltage is fine, I also tried jumping it off of another vehicle just to verify this, and the behavior is the same.

When the problem shows up, the dome light, radio, etc. are on as long as the key is OFF or in the ACC position. When I turn the key to the ON or START positions, the voltage disappears. The dome light turns off, radio shuts off, voltage gauge drops to basically nothing. It doesn't always come back immediately when I switch the ignition switch off, but sometimes it does.

Occaisonally the voltage gauge will creep up to 8V or so, but as soon as I try to crank it, it drops right back down to nothing.

I can fiddle with the ignition switch on/off, start, acc, back and forth, and it doesn't seem to help. Same with moving the shift lever out of park, into gear, and back to park again.

Is there a relay that provides 12V power to the ignition switch? If so, I'm wondering if it's not getting a reliable 12V to energize it for some reason (maybe a bad connection?).

Is there a fusible link that feeds 12V power to the ignition switch? Maybe it's got a bad spot in the link that's causing problems.

What about the ignition switch itself, does that sound like the likely culprit?

After opening and shutting the hood and doors enough times, waiting a few days, and holding my mouth just right, the problem amazingly corrects itself and I'm good to go again, until it shows up next time...

I'd appreciate any help you can give!

Thanks

 

 

I've already tried that. I pulled the starter a few months back and had it rebuilt. Any other thoughts?

Thanks

 

Just to clarify what your saying. When you turn the key to ACC everything works fine. When you turn the key to ON everything goes out. Everything also goes out when you try cranking the starter.