The Dreaded Intermittent Electrical Problem!

Just wondering how I should go about trying to trace down an apparent short somewhere in the electrical system?

Bike is a 1982 KZ-750N1 (Spectre) with about 25,000 miles on it. It's run fine since I bought it in September of 2007 but recently has developed the dreaded Intermittent Electrical Problem!

Here's what happened: On July 12th I took a long, fast ride from Englewood (Denver suburb) up to Ft Collins, about 60 miles North. The ride was fine and I parked the bike. Several hours later I came out to start the bike and no electrical power at all - no lights, no nothing.

Checked the fuses and the 30A main fuse was blown - a little slag and a burn mark on the right side of the fuse as you look at it (towards the front of the bike.)

So we put in a new fuse and not more than 5 miles later, everything goes dead - yup, same fuse.

After that I replaced the fuse and it was fine for the 65+ mile trip back to Englewood.

Since then it's been intermittently going out. Sometimes I can ride 100 miles without a problem and on another occasion it went out twice within a space of 10 blocks.

I've tried to analyze every failure to see if there was a common denominator anywhere but I can't figure one out. Thank God it hasn't gone out when I was in the middle of a multi-lane freeway at high speed but I'm sure that's pretty much a fluke.

I'm not much of a mechanic beyond basic fluid changing but I was wondering if anyone else had had a similar problem and whether there was a well known or common point of failure on these bikes that I should look at first? Obviously taking it to a shop is an option too, and there's a good one nearby but I'm trying not to put too much $$ into this bike right now.

Any help would be appreciated!

ZappBranigan; I hate electricity and it hates me! Check the usual things (if you haven't already). Make sure the fuses are held tightly in clean connections. Next step, follow the line and see if you can find a chaffed spot where current is going to ground. Any recent work done? I like to unplug the connectors in the loom and clean and reassemble with silicone grease. These problems can drive you nuts. . . Good luck and ride safe, Steve

when i had that prob it was exact as shighley has said....a wire had worn through and was toching under my sidecover to the frame....my bike had been rigged/routed really shitty by the last owner and i have had stuff wiggle free,ground,fail...everything...i finally took my whole wire hrness off ,marking anything i might forget with a piece of painters tape and a note to myself...re-routed,recrimpend,re-zip tied,and eliminated all his excess scabs of wire....and have not had to walk since....but the main thing when i had the fuses going out was an exposed wire on a black one under my sidecover hidden by a zip tie.....good luck

Here is the most basic method I know:

1) Charge your battery if you can.
2) Disconnect the Black lead form the (-) Battery terminal... or Red form the (+) Battery terminal, it does not matter which one.
3) Connect one of the following test setups in series with the Battery terminal and lead:
3.1) A 12 V light bulb,
3.2) A 12 V test light,
3.3) A 12 V test buzzer or,
3.4) A 12 V horn... you get the idea.
4) With the Ignition Switch OFF, go through your harness and wiggle the wires while looking/listening for the test setup to go on/start buzzing.
5) With the Ignition Switch ON, repeat the test except this time the looking/listening for the test setup to go on/stop buzzing.
6) Be prepared to open the Ignition switch and check/test for solder joint failure and or circuit board micro breaks (don't ask how I know this :blush: ).
7) Be prepared to pull the wires out of the Head Light to test for failures at or near the grommet.
Be prepared to open the harness at or near the Steering Neck for failures. This is where wires tend to exhibit fatigue due to repetitive movement.
9) Be prepared to open the left and right switch gear to search for rust and or broken parts. CAUTION: watch out for fling springs, ball bearings and stuff. Do indoors on White sheet (again don't ask :blush: ).
10) Be prepared to follow the heavy gauge wire from the Starter Solenoid (Relay) to the starter for bare ware wire exposure. Especially near bends and grommets.
11) If you can reproduce the fault symptom your are pretty much home free. Be prepare to find and repair/replace any internal wire breaks, insulation break downs, exposed wires, rubber grommet failures, etc. Often, shrink tubing will solve the problem temporarily.

Best of success.

PS
Would you mind adding your model, year and location to your signature to motivate others to help you out... and yes, it is considered very friendly here.
Bill

The glass type fuse can cause resistance in their metal connectors after time.
My main fuse used to blow like yours until I installed a blade type fuse in it's place. No problems ever since.

Now admit it... you just got to love the one step solutions. :laugh: :laugh: :laugh:

30 year old fuse box, what can you expect. I had to go in the same direction two seasons ago. I decided to replaced all the fuses at once. See below:



Best of success.

Electrical troubleshooting can and is a very time consuming process. A comfortable place to sit,the factory shop manual with the wiring diagram(I don't like either Clymer or Haynes as the diagrams or in black and white but the ones from www.repairmanual.com have colored drawings).

The first place I'd check would be where the main harness goes up toward the headlight as this area flexes a lot and may have a wire or two rubbing together. Another place to look is anywhere wires can be pinched shorting to ground like in/on the handle bar control pods. If the ignition switch is the original then it may be the cause of the problem so don't rule it out.

I'd check and clean each electrical connection from the battery and all fuse block clips. Some plastic friendly electrical contact cleaner, a brass bristle brush to scrub the many and various bullet connectors, and 400-600 grit sandpaper to clean contacts with.

I use a brand called De-oxit from Caig Labs out of San Diego www.de-oxit.com on all cordless phone charging cradles,audio patch cables and all electrical connectors on my 82 GPZ1100 B2. I think Radio Shack might carry the De-oxit spray cleaner/preservative.

As said before a multimeter,continuity light and plenty of patience as this can have you talking to yourself and get funny answers.

See what happens when you come up to Fort Fun and not visit the local KZR folks? :laugh:


I like Bill's way of doing the troubleshooting. When I've had problems like yours, I end up going through lots of 20 amp fuses until I can find the culpert.

The only thing I can add is don't pass up any location that your wiring can be in contact with metal. I spent 2 weeks tracking down a short in my kill switch where one of the wires had just worn through the insulation and was making contact with the handlebars. Very frustrating. In my kz900 project, I've discovered several wires that have worn their insulation as they enter the headlight bucket.

Good luck and let me know next time your up here!

Switch gear short circuits! :X

Three seasons ago I had one in my left switch gear assembly... all small, curled up and tucked behind a screw down retaining plate. :S

I could reproduce the short but could never find or test it out to the individual wire. So I cheated. I used just a bit of heat shrink on each of the suspect wires in the suspected area and the problem disappeared.

Never did find out which one it was and never lost any sleep over it either.

Best of success.

Two seasons ago I had the same problem with a main fuse blowing - I wish I had bill's method back then.

I was lucky in that I managed to find the problem in a couple of hours. Behind the headlight in the headlight shell is a big mess of wires and connections. I found that a piece of electrical tape (blame PO) which covered a connection had fallen off and the connection was shorting out to the inside of the headlight shell. Easy fix. I got rid of the tape and used liquid electrical tape which I think is a great product.

While on the subject of electrical I also upgraded the fuses to the blade style like the guys above. well worth it.

Good luck

Blowing a 30A fuse requires what we call a "hard short", not likely to be a flaky coil or something wimpy. I agree that this kind of failure is so dangerous you have to get to the bottom of it. The only real way to run it is to just trace the wire(s) physically even if you have to unwrap the harness to eyeball them.

It's a royal pain in the butt, and I have done it before to get the peace of mind. You are looking for a main power line or branch from it that is able to touch a hard ground.

Old bikes and electrical gremlins are buddies. Wise person taught me to go through all the connections and inspect the wires. Clean the connections and tighten them up. Then di-electric grease to keep them that way. If you are going to keep the bike and ride it it is good insurance. 25 miles out on a 50 mile ride and the bike goes flatline is not a happy ride. Takes a few hours but saves a ton as you look for the culprit or chase them through the harness. Bad connections can heat fuses to the point of failure too.