Spark plug wires will not cause a popped fuse; you can ground one sparkplug wire to the chassis, and the fuse should be fine.  However, if you replaced the plug wires, you might've jiggled the +12v leads from the battery to the coils, which would pop a fuse if they shorted.

I had a friend who had a "mystery short"; he replaced the fuse with a circuit breaker, so he could reset it .  That was the first bike I ever rode.

Quote from: seshadri_srinathOK that additional earth connection from negative of battery to wiring harness... that will be my first suspect ... running on 1 cyl is what it does if its bad ... and might make it blow fuses as well...
Cool.
Srinath.

If you'r talking about the two black-white wires, one is the ground for the RR module.  This one would affect the charging ckt.  A bad connection in this wire would probably cause the regulator to go wacky.  Since the charging is through the fuse...... who knows, maybe this wire is the culprit.

The other black-white wire furnishes ground to just about everything else that needs it, including the ignition control unit (ICU).  I would think a bad ground connection to the ICU could cause missfires but not blow the fuse.

Good luck

OK, I got some more info for the GS gurus.  I put the tank and the seat back on.  It starts and warms up fine.  I can rev the motor and it runs ok.  I did notice that I sometimes get a quick "pop" or "tick" when I blip the throttle, and I don't remember that prior to the issue.  Here's the BIG thing I noticed:

As soon as I start MOVING, it dies.  Every single time.  I can put it in first gear with the clutch in, and rev it all I want.  But as soon as I release the clutch and start moving, it pops the fuse.  What the hell!?!?!

Quote from: mrblinkOK, I got some more info for the GS gurus.  I put the tank and the seat back on.  It starts and warms up fine.  I can rev the motor and it runs ok.  I did notice that I sometimes get a quick "pop" or "tick" when I blip the throttle, and I don't remember that prior to the issue.  Here's the BIG thing I noticed:

As soon as I start MOVING, it dies.  Every single time.  I can put it in first gear with the clutch in, and rev it all I want.  But as soon as I release the clutch and start moving, it pops the fuse.  What the hell!?!?!

Since it dies as soon as the bike moves, I would suspect the kickstand switch. Try to jumper the wires(I don't know if it needs to be open or closed). Also, will it start with the clutch pulled in and in gear? Or does it die when you pull in the clutch and put it in gear? There's another switch at the clutch handle. Just more possibilities. :dunno:

It doesn't die until I let the clutch out.

The clutch switch has no effect after the bike has started.  

On the other hand the sidestand relay must remain operated to keep the bike running.  The components in this part of the circuit are, in addition to the sidestand relay, the sidestand switch, the diodes and the neutral switch.

If you'r in gear then the neutral switch and diodes are out of the circuit and the sidestand switch or related wiring is the culprit.

The sidestand switch (or that circuit) is definitely the culprit.  The clutch switch and sidestand switch seem to both work as they should.  If it's in first, and the stand is down, the bike will not start (but the fuse is good).  If the stand is up, the bike will start, but blow the fuse after a second or two.

Now, I traced the wires back to the ECU.  There is a green wire (assuming ground), and a black wire with a white stripe.  If I disconnect them, the bike won't start (fuse OK).  If I short them nearest the ECU (taking the switch out of the loop), the fuse blows.  I don't understand how the circuit works, so I don't know if those two (green and black/white) wires are supposed to be shorted to close the circuit.  We're definitely getting closer!!

According to my Clymer manual, the green and black/white wires ARE shorted to complete the circuit.  So the switch is OK, meaning that there might be a more serious problem.  

Quote from: mrblinkThe sidestand switch (or that circuit) is definitely the culprit.  The clutch switch and sidestand switch seem to both work as they should.  If it's in first, and the stand is down, the bike will not start (but the fuse is good).  If the stand is up, the bike will start, but blow the fuse after a second or two.

Does the engine start if the sidestand is down and the transmission in neutral?

Quote from: mrblink
Now, I traced the wires back to the ECU.  

What do you mean by ECU?

Quote from: mrblink
There is a green wire (assuming ground), and a black wire with a white stripe.  If I disconnect them, the bike won't start (fuse OK).  If I short them nearest the ECU (taking the switch out of the loop), the fuse blows.  I don't understand how the circuit works, so I don't know if those two (green and black/white) wires are supposed to be shorted to close the circuit.  We're definitely getting closerquo!!

When the sidestand is down the green and black-white wires are not connected.  When the sidestand is up the two wires are connected and ground from the black-white wire is placed on the green wire.  This operates the sidestand relay which in turn places 12V through the engine stop switch to  the ignition ckt.

The only way this could blow the fuse is if the sidestand relay winding is shorted.

QuoteDoes the engine start if the sidestand is down and the transmission in neutral?

Yes

QuoteWhat do you mean by ECU?

That block on the left side with all the wires coming out of it.  It may not be the ECU, but it looked like one.  Better than calling it the "thingey" I suppose.  

QuoteWhen the sidestand is down the green and black-white wires are not connected. When the sidestand is up the two wires are connected and ground from the black-white wire is placed on the green wire. This operates the sidestand relay which in turn places 12V through the engine stop switch to the ignition ckt.

Ya.  I was able to figure that out by looking at the Clymer manual (RTFM).  It tells how to test the relay, but my battery in my volt meter is almost dead, so I'm on my way to Radio Shack.  There was a lot of goop and stuff on the wiring harness that connects to the sidestand relay, and a cleaned it up the best I could.  Is there a way to jumper two of the wires in that harness, or does it need the relay in order to complete the circuit?  It seems like the 12V power to the relay only serves as a method of completing the sidestand circuit within the relay??   :dunno:

I can back Srinath when it comes to the secondary ground causing the bike to run poorly(part of what I am working with).  It is the small wire coming off of the negative battery terminal.  I just replace mine with a bullet connector(I was supprised at the amount of RUST on that connection) and replaced the wire all the way back to the main harness.  It solved the problem I had, and led me to another(hope it doesn't do that to you).

Good Luck
Don
Shadowhawk
'92GS500
'83GS450LD

I don't think that's my problem.  The wire is in good shape, and the bike seems to run ok.  It only runs like poop when the fuse blows and it doesn't die immediately.  I'm pretty sure that my problem is at the sidestand relay, but some other force may have killed the relay.

Here is a
simplified drawing of the starting ckt.

Hope it helps.

About ready to give up...  I checked the relay, but can't make heads or tails of it.  When I applied 12V to it or took the current off, it would click, which is probably good.  When it's hooked up and the bike's on (not running, just power), it clicks when I push the sidestand switch in and let it out.  I thought everything was cool, so I started it up.  It ran for about a minute in first gear, with the clutch in, and the side stand up, giving it little blips on the throttle.  As soon as I started to take off, it died again.  It still seems like it might run longer when it's totally cold.  When it's warm, it dies in about 2 seconds (when I put the stand up and put it in first).  The relay does seem to get a little warm after a bit, but I dunno if that means anything.  

I may have to bribe one of the local gurus to come help me fix it.  What will it take?  Money?  Food?  Beer??  I have all those things!   :mrgreen:  (but not enough money to take it to the shop @ $65 per hour X many many hours...  I'd rather put that money toward a new bike and part this one out)

BikeBandit has the sidestand relay listed as:  "RELAY ASSY,FUEL".  Just wanted to verify in case I end up ordering one.  It's part# 21 on this schematic:

http://houseofmotorcycles.bikebandit.com/partsbandit/showschematic~dept_id~722662.asp

That looks like the relay. Strange name.

I would check the relay winding resistance before buying a new one.

Pull the relay and with an ohmeter check for 87 ohms.  With the rubber mounting slot facing toward you, the two terminals on the right are the winding.

The reading would have to be very low, about 1 ohm or less, to draw enough current to blow the fuse.

If it was my ride I would try and eliminate the POS relay/switch. It's not a critical component. Dirt bikes don't have them. If you take off with the stand down, you'll know soon enough. :mrgreen:

John - Thanks.  The Clymer manual didn't say exactly what the ohm reading should be, so I was only able to test current.  I'll check it when I get home.  I really need to take an electronics course.  This is fun stuff when you understand it!  Do you know what would FRY the relay in the first place?

Ed - I hear ya.  The whole circuit seems a little too complicated to eliminate it.  If there is a way to do it, I would LOVE to hear it.  Anyone??

Have you seen the wiring diagram from the Haynes manual? It's in full  COLOR!

It hasn't been mentioned in this thread yet - not that you need even MORE reference info at this point....

Nothing like total confusion, in FULL COLOR!!   :mrgreen: