Baffling Fuse Issue

[Guest]

THe MAIN fuse keeps blowing, but not consistently, and I just witnessed it happen as I was shutting the bike off! Turned the run switch to OFF and as the engine stopped, the fuse blew, a few days ago, it blew as I was taking off in 1st..
Where to start?

1982 GS550L

[Rich82GS750TZ]

You could just have a wire rubbed bare somewhere that is shorting out.

or

A year and half ago, I was where you are now. If your bike still has the original shunt type Regulator/Rectifier (RR), it has likely burned out the stator, possibly melted the connector between the RR and stator. The good thing is that this is possibly the most talked about subject on this forum. You are on your way to overhauling your charging system for the better. It involves replacing the stator (if it's bad), definitely a new (or used) series type RR like the Shindengen SH775 (found on Polaris ATVs and Seadoo machines), cleaning up all of your wiring, and creating a single point ground (SPG). Don't worry, there are good folks here to help (smarter ones than me will give you exact technical advice if you ask).

Get yourself a voltmeter if you don't have one. Try replacing the fuse and getting your engine to run. See the quicktest linked in my signature and if you can, report the numbers, all of them, here. You got this.

[Redman]

I am not that familir with 550s, but when you say MAIN fuse, I gather that means you do have other fuses (in a fuse block).
If so, lets first verify one thing: THe main fuse is a 15amp and the others are 10 amp. If they are all 10s, well that can be your problem.

Yah, electrical problems that occur on random occassion are hard to troubleshoot.
If you can do something to cause it to happen, like wiggle arond wireing harnesss (say main harness going around steering neck), then can narrow down some.

SOmetimes the horns (without hitting the horn button) can have an internal problem that will blow the signal fuse or maybe the main fuse. SO can try tapping on the horns and see if that causes fuse to blow. Or can disconnect the wiring from the horn(s) and see how long you go without blowing the fuse.

The probelm with the r/r that can blow main fuse will most likley not be random, will be everytime, immmeadiatly .. Which is not what you said.

[salty_monk]

Another place to check is inside the right hand control. I think you'd see that symptom if the wiring to the kill switch was shorting out.. I may be wrong though!

[Tom R]

Another place to check is inside the right hand control. I think you'd see that symptom if the wiring to the kill switch was shorting out.. I may be wrong though!

This is why I never use the right hand control kill switch on old bikes.... it will fail eventually and is a pain and expensive to replace. I use the key to shut it off.... cheap to replace and accessible. Again though, it may not be your problem, but still something to be mindful of.

[alabamatom69]

Rectifier was bad - I assume due to running with an accidentally disconnected ground a few weeks ago. All is good now