blown fuse

[matt g]

I left my key on now when the contacts on the points touch it blows my fuse. When the point gap is open the fuse wont blow.

[rzgkane]

Are you saying that when the key is in the "ignition on" position your fuse blows immediately? If so, I would check for a direct short to ground in the black wire that fees the coil.

Does the fuse blow in the 0, 1 or 4 position? If not, you have narrowed things down significantly to only the circuits unique to the #'s 2 and 3 position. If it blows in the #3 position and not the #2 position, you should look for a short to ground in the headlight circuit. It sounds like you have a consistent problem which is much easier to diagnose than an intermittent short.

We used to say "hard-wire in place of the fuse and look for the smoke" but that's a pretty prehistoric way of finding a short.

You might buy what is called a "short checker" that will allow the circuit to remain hot without melting any wires and will illuminate a bulb while the short exists. You disconnect one wire at a time and when the light has gone out you have found your faulty circuit.

Good luck. And please report back what you find. I love to hear where the shorts like to hide.



C77 Wiring Diagram No Winkers by rzgkane, on Flickr

I left my key on now when the contacts on the points touch it blows my fuse. When the point gap is open the fuse wont blow.

[rzgkane]

Are you saying that when the key is in the "ignition on" position your fuse blows immediately? If so, I would check for a direct short to ground in the black wire that feeds the coil or a coil that is itself shorted.

Does the fuse blow in the 0, 1 or 4 position? If not, you have narrowed things down significantly to only the circuits unique to the #'s 2 and 3 position. If it blows in the #3 position and not the #2 position, you should look for a short to ground in the headlight circuit. It sounds like you have a consistent problem which is much easier to diagnose than an intermittent short.

We used to say "hard-wire in place of the fuse and look for the smoke" but that's a pretty prehistoric way of finding a short.

You might buy what is called a "short checker" that will allow the circuit to remain hot without melting any wires and will illuminate a bulb while the short exists. You disconnect one wire at a time and when the light has gone out you have found your faulty circuit.

Good luck. And please report back what you find. I love to hear where the shorts like to hide.



C77 Wiring Diagram No Winkers by rzgkane, on Flickr

I left my key on now when the contacts on the points touch it blows my fuse. When the point gap is open the fuse wont blow.

[matt g]

Thanks for the info. I rode it the day before shut the petcock off ran it out of fuel forgot to turn the key off.Came next day battery was dead charged it up fuse was blown.Kept blowing fuses turned engine over by hand till points were open every thing works lights horn.Turn engine till points close fuse blows.

[teazer]

Sounds like a coil overheated when it was left on and not running. Check your coils or swap a new pair in to see if that fixes it.