Main Fuse blows when I turn on ignition

[mat163]

I have a 1985 GS550E and when I turn the ignition switch to the "ON" position, it immediately blows the "Main" fuse. The bike was sitting in the rain for a couple of weeks and when it finally cleared up, I decided to ride it. I turned it to the on position, and got no lights. I tested the battery, and it was at 12.45 Volts. I checked the main fuse, and it was blown. I put a new main fuse in it, and theat one blew too. Does anyone have any ideas on what the problem might be? Thanks for your time.

[justmount1]

u need to check the wiring on your bike you have a faulty wire somewhere or a bad ground somewhere

[Redman]

Bad ground wire will not blow a fuse (just that stuff on that circuit will not work).

To trouble shoot the main fuse blowing as soon as turn on ignition:
Verify that the main is 15 and the others are not.
Go get some spare 15 amp fuses.
Pull out all the fuses except the main (the 15 amp one, the others should be 10s). And dissconnect the R/R (regulator/rectifyer - silver thing under battery box).
Turn on ignition then. If main fuse blows then can look for problem in the main power wiring between the ignition switch and fuse block.
If it doesnt blow: Then replace fuses one at a time to try to narrow it down to which circuit. IF get them all back in without blowing fuses, then plug the r/r back in.

I suspect you will find its the R/R. But thats just a suspecion.
Ohter note: if the R/R is at fault (no pun intended), then you should suspect the stator also. But we can discuss that later if need be.

Or... maybe it will be okay (for a while) after it dryes out some more.

.

[mighty13d]

one of the positive wires is probably grounding out somewhere. check every wire that you are able to see for any wear on it.

[spyug]

You are going to need to do some wire tracing as you have a"short" somewhere coming or going to the fuse. There is likely a wire (i.e. a line carrying power) that has broken insulation allowing the wire to touch the frame or some other metal part.

To find a short you can use a hand held magnetic compass and a 5amp resettable circuit breaker (saves blowing fuse after fuse) connected to 2 lengths of wire with alligator clips on the ends.

The circuit breaker is used in place of the fuse. The compass is used to find the short. If you hold the compass to a wire carrying power the needle will swing back and forth indicating current flow. Moving along the wire you want to see the compass swing. When it doesn't any more you have found the likely site of the short. It takes some practice but you can soon learn to be within 6 or so inches of the break.

It can be fiddly as the wires go every which way and in the case of some they are wrapped in the loom. You may need to unwrap some lengths as wires can chafe against other wires. Refer to your manual for your electrical schematic to find which wires are powered and you can verify them with a probe of a circuit tester.

Give this a try and see what you find. Let us know.

Good luck. fingers crossed for you.

Cheers,
Spyug

[mat163]

Thank you guys so much for the help. I really liked the compass idea. I remembered that not too long ago, I ran the batter down because I accidentally left the ignition in the "on" position overnight. I recharged the battery, but I realized that the problem might be the battery. To test this, I disconnected the battery and ran the bike off of a jump box. The fuse didn't blow. $50 later and a new battery installed, the bike no longer blows the fuse. I must have internally shorted the battery. Thanks for all of your time.

[tas850g]

i had the same problem. the 4 wires coming off the key ignition and heading to the nylon connector were bare and somehow the hot wire would connect with one of the others. Fixed the bare wires, no more blown main fuse.