Recording this for posterity.  Our Bandita – Dita for short – a 1991 Suzuki Bandit GSF400 went to live with a new family in 2010.

Got a call yesterday from the other half. He told me that the Bandit had broken down on the way to work. He’d been riding, then suddenly there were no lights, nothing.

Thinking it was the regulator rectifier,… again, I went out to the shed and got the spare RR and the loading ramp. We arranged for me to pick him up after work and we would go get the bike.

We brought her home, cos neither of us felt like messing around with her in the rain, and checked a few of the obvious things.

Battery Level – 12.25V A little low, but not low enough to cause the bike to lose -all- power. OK,.. likely not charging system related.

Check the fuses. Main (25A) fuse was blown. Hmm,.. what would have caused that? Put the spare in, and she blew it as soon as it -touched- the fuse box, we didn’t even manage to get it inserted!

This would indicate that the short is with something that has a live power feed to it even without ignition power. That should narrow the field a little.

Did I mention that I -hate- electrical problems! It’s midnight by now, so we head inside. The other half to bed, me to research on the net.

Boy, am I missing my forums.banditalley.net right now.

5am I finally give up, I have a list of things to try in the morning.

I found some really good troubleshooting tips while surfing last night, so I might as well mention them.

1. If you’re blowing the main fuse, try removing all fuses, except the main and see if the bike will run without blowing the fuse.

If it does, then try adding the fuses back in, one at a time til it pops the fuse again. (try fuse in slot 1, then try to recreate the problem, if it doesn’t, remove that fuse, and try one in slot 2, etc etc.)

If you insert a fuse and it or the main one blows, check the wiring diagram to find out what that fuse protects. This will give you a place to start troubleshooting.

If none of the fuses seems to cause the main to blow, put all the fuses back in, and consult your wiring diagram in your service manual. It should indicate what is protected by which fuse.

2. Make sure that you use a known good fuse, test it for resistance before you use it.

3. Do NOT use a fuse that’s rated higher than the proper fuse in the fusebox. This is a good way to burn down your bike! (I already knew this, but it bears repeating.)

4. Do not use a paper clip, piece of tinfoil, or any other item that is not a fuse to bridge the fuse link. See above, you can and likely will burn the bike down.

5. Always carry spares fuses, even more than what the bike holds by default. This can make the difference between a great ride, and a huge tow bill.

Ok,.. back to the nightmare at hand.

It appears according to the wiring diagram, ( you do have a copy of your service manual, right?) that the fusebox and the starter relay are live when there isn’t ignition power.

Additionally, the RR and the ignition switch appear to be the only things “fused” by the so-called “main” fuse. Interesting.

Ok, so, by process of elimination, I likely have a problem with the RR or the ignition switch, or something between one of these and the battery. (i.e. a bare wire, etc.)

Since the RR has been a problem on this bike before, I opt to check it first. In my case, when the RR failed on the Bandit before, I replaced it with a Honda CB400 RR. This meant that the wiring had to be “kludged” a little, so of course, I peeled this apart first.

As I peeled the electrical tape off the “kludge”, I felt water on my hands. (She’d been ridden in the rain a few days earlier)I was suddenly sure that I was on the right track. I exposed the wiring, and found that it had slipped apart a little. This coupled with the water had likely caused a dead short. To test my theory, I disconnected the RR from the bike.

This is something you can do as a troubleshooting test. Disconnect the power leads ( i.e connector containing the black and red leads on a Suzuki, or the green and red leads on a Honda, other bikes of course may be different.) and if you want, the stator leads (connector containing 3 yellow leads) as well, for good measure. Replace the fuse. Did it pop? If not, Now start the bike.

In a pinch, the bike can be run like this for a short time. As the regulator is not attached, your battery is not charging. Essentially, this becomes a total loss system. It can be enough to get you home in an emergency. Be sure to charge that battery up as soon as you get home, and fix your regulator problem immediately! Or you will start to destroy parts of your charging system.

If it still pops the fuse with the regulator rectifier disconnected, your problem lies elsewhere. (Good second place to look would of course be the ignition switch.)

In my case, the bike started and ran. YAY!! Ok,.. as you can see above, the regulator was not faulty, but the wiring was loose and caused a problem. So, don’t throw the baby out with the bathwater, it could be something simple.

I re-wired the RR to the bike. I removed the connector that I had retained from her original wiring, and plugged the blades from the RR into the female ends. This time I used shrink tube and a lot more electrical tape. I also hid the connection behind the battery, so hopefully it will be a little more resilient against rain.

In my defence, it did last a year before it failed.

I looked closely at the original connector, and it appears to have “worn” the wall between the ground and live wires down to nothing in a spot or two, add to this a little water, and you have yourself a little fuse popping party.

Make sure you charge the battery up totally after all this testing, and for good measure, maybe run everything through this test: http://www.electrosport.com/electrosport_fault_finding.html Make sure that the battery is fully charged first though, or you may get unexpected results.

Now, what are you doing here still? Take the girl for a ride! Celebrate the fact that she did exactly what she was supposed to. She blew the fuse instead of burning down or frying the wire harness.