Yes, as electrical connections deteriorate, the resistance goes up, as RG said. Current flow doesn't stop, but it degrades, causing issues.So you think a bad fuse connection could cause something like that. It just seems odd to me that a bad fuse connection would allow the bike to idle. Not that I am at all opposed to checking it out.
For the 1980 to 1984 years, there are a couple of common problem areas that keep popping up.
1...............A weak magnet on the alternator rotor.
2.............. The old original, 4 position, fuse panel using glass fuses.
I suggest you eliminate these two potential problem areas, before chasing other less likely areas.
I already told you how to test for the weak magnet.
If your bike still has the original fuse panel, then its worn out, and must be replaced. Buy some automotive, in line blade type fuse holders, and install them (solder and heat shrink insulation).
The magnet flying by the pickup induces a big sloppy voltage that no doubt gets amplified and squared up and fed into the primitive digital circuitry... That involves chopping the top of the pulse off such that there's plenty of amplitude to spare. You have to ask yourself what are the odds of the magnet being on the hairy edge such that after twenty mi. of running fine the magnet goes over the cliff. Is it even possible? And you have to ask yourself what is more likely that could cause the same symptoms.The original tiny magnets are just getting old, and can fail at any time.
xjwmx......................it may have been on the verge of failing for a while. The TCI circuitry likely has the ability to compensate (amplify a weak pulse) as the magnet slowly gets weaker, until one day it just can't detect the pulses properly.
I respect that. I have decades of software testing and debugging experience in my work life, which is the logic side of this. A lot of the time you confront a problem that has to be caused by X, then you finally realize it was some other thing doing something in a way you never considered before. Another lot of it is poor reporting from the field -- i.e. something happened that really didn't...I have a lot of experience trouble shooting mechanical, electrical, electronic, pneumatic and hydraulic systems during my work life.
Right. Don't assume, in other words.Another basic rule of troubleshooting: Logic out the issue after testing, never before.