I have replaced an ignition switch and now have a new electrical gremlin. I also replaced some badley worn power supply to the starter including the fusable link with an inline 30 amp fuse. now when I try to start, I lose all power to the starter. I have a battery quick disconnect and when I disconnect and then reconnect I have dash lights until I try to start. At that point I lose all power to dash and to starter. very reproducible . I still don't have all my horn back together till I resove this. pushing the horn button does allow current to horn relay. not sure how all this relates, I really thought the ignition switch was the culprit for not starting occasionally and then rarely. I have been running great with rebuilt 350 and new performace electronic distributor in 1969. any thoughts?

 

I recently had the same problem in my '68...time consuming problem/took a couple hours to repair all problems..the yellow wire to the starter solenoid was damaged in two locations.....the purple wire to the solenoid was damaged.....the RED 12?gage wire to the startersolenoid that runs across the firewall in the main harness was damaged.....the neutral safety switch was out of adjustment just enough that it caused a loss of power to the solenoid occasionally when the key was turned to the "crank" position......there was no ignition switch when I bought the car---I installed a new switch.....then ended up with all the problems that you have....

And I added a frame ground cable from the starter grounding lug to a clean spot on the frame which caused the starter to crank much faster.

 

It sounds like you have a poor connection that is breaking and then re-connects when you mess with the battery connection. Try to start and when you lose power, take your meter and start at the battery connection and work forward measuring the voltage as you go. When you find no voltage the problem is between there and the last place you measured voltage.

Also, my opinion would be that a 30A fuse for the main power in the car is way too small. I really hope you're not using one of those inline ATO fuse holders for that fuse because that whole setup would be woefully inadequate.

 

The only fuse that I know of that would be in your engine compartment is the 30 amp "glass-style" fuse for the high speed blower for a car with A/C.

There is NO FUSE down by your starter...and that is what I feel is part of your problem. All you need is a fusible link which is 4 sizes smaller than the wire that it is attached to. SO..a 10 gauge wire would take a 14 gauge fusible link. Approximately 4 to 5 inches of fusible link. The length of fusible link is also important...so having 2 feet of it is incorrect.

You have to understand that when a circuit is energized and going to be used...the contacts have to be clean and correct for the amount of amps that the circuit requires can actually carry it. A circuit can have 12 volts on it but that does not matter. what matter sis if the circuit can carry the amp load required. SO...when you go and try to crank the engine and everything goes dead...I bet it has to do with the in-line fuse NOT being able to handle the load so it fails and more than likely arcs or get hot and the tension that the fuse once had is now getting worse....thus allowing for more arcing and so on.

Remove your battery disconnect...because it falls under the same explanation above. It takes so many amps to crank your engine that if this disconnect is not REALLY GOOD...it can arc and fail.

Also...if the terminal at your starter for your battery cable is loose...tighten it up. I am not talking about the nut that holds your cable on...but rather the nut that holds the terminal bolt to your solenoid. The same holds true for the purple wire from your ignition switch that makes the starter work. Check the terminal nut.

As mentioned by others...make sure your battery cables are CLEAN AND TIGHT...remove the QUICK DISCONNECT for testing.

DUB

 

Thanks to all. Have been distracted with other projects. will follow up with results.