Need help from electrical gurus w/intermittent short blowing ignition fuse

[niided]

I have been able to complete many diy projects and solve/repair a bunch problems on my m/c's and cars by searching

Google. I also have this posted on Ninja 250 org. forum. Most of my time is spent on the Adv forum.

But this one electrical problem w/my Ninja 250 has me totally stumped . I have read extensively about the problems that

could be cause of the #3 10a igniton fuse blowing. My son's 2004 Ninja 250 has an intermittent short that is causing #3

ignition fuse to blow. The first time it happened while on the hwy, lost power and had to be towed home. #3 fuse was blown.

Here is what has transpired so far;

1. Replaced fuse and turned on ignition, immediate pop.

2. Removed gas tank to look for obvious breaks in harness and connections, nothing found.

3. put new fuse in, good to go. Started up bike, tried pulling and twisting wires at obvious connections relating to #3 fuse, all

the safety switches, ignition, etc. Could not recreate the short.

4. Put the tank back on, tried starting, as soon as I turned the key, the fuse immediately popped.

5. Took the tank off was going to do ohms check on connections, but short went away.

6. Tried running the bike for about 30 minutes while on a stand, revving up rpms, thinking it might be heat related. Bike

kept running.

7. Buttoned the bike back up. Took it for a spin, 10 miles from my house, blew the fuse, towed back home.

8. With the #3 fuse blown, was going to track the short by w/multimeter, had to take the tank off to get to the connections,

short disappears again.

9. I now have the harness pretty much apart and checking individual wires for any sort of fraying or pin holes. Have found

nothing.

10. I took apart both bar end housings to check the kill switch and clutch switch wiring. Took the bottom cap off the ignition to

check wiring. Checked the wiring at kick stand switch and neutral light switch at engine. Everything looks good.

My friend thinks it might be coil related and t when it heats up while riding it might cause a short. I have blown the fuse while

the bike was cold after placing the tank back on, so I don't know about his theory. I pulled apart the junction box and all the

pins and solder points look good. Looking at the schematics , could a bad rectifier or ignition module cause a short to the

#3 fuse? How about the coil? By the description I provided, it seems to be that it is most likely a wire to ground causing a

major short. I have closely inspected the wires under the tank for even a small pinhole but nada. All the plastic connectors

are intact. I have traced the wires forward to dash and handle bars. The only thing I haven't traced are the wires running

from the junction box rearward as they are not connected to ignition fuse. Any ideas would be welcome. I am about to throw

in the towel and maybe buy complete new harness, but that might not even be my problem.

The big problem is that the bike is running fine right now so I can't use the meter to isolate the culprit.

Thanks for your time,

D.T. Niide

[ScEd]

Usually a wire shorting to ground will reveal it's-self soon. Sounds like you have checked the harness thorough enough to begin looking at components such as the rectifier. You could try isolating the components one at a time with a new feed wire from the battery fused separately. This would at least allow you to eliminate the possibilities.

[vtduc]

From your description, I would suggest the wire harness may be rubbing and grounding on the underside of the gas tank.

[mark1150]

It does sound like the gas tank has a part in this i.e. shorting.
I'd be inclined to insulate the tank by means of plastic builders bags and tape, if only to isolate the area.
If it runs fine while insulated you can be almost sure that the problem lies in the loom beneath the tank.
Let us know how you get on.

[concours]

This http://www.gtc.ca/EN/FF310_EN.html or the old fashioned "smoke test" . Put a really BIG fuse, or NO fuse in and look for the smoke...

[Guy Young]

Personally, I would make up a test light to replace the fuse so you don’t keep blowing them. A “smoke test” is certainly one way to do it, but you risk further damage to the wiring harness.

Pick up a “power on” test light from one of the auto parts places, similar to this:



http://www.autozone.com/autozone/acc...uestid=7597596

Get a couple of male .250 spade connectors and crimp on some leads that are several inches long.
Pull the #3 fuse and plug the spade connectors into the j-boxes’ fuse clips. Narrow the width of the spades (if necessary) so they will fit into the fuse clips.

Alternate to the above "packaged" test light if you have a soldering iron/gun and minimal soldering skills, would be to get a single filament 12v automotive bulb, and solder the leads from the spade connectors directly to the bulb.

Connect the spade’s leads across test light and turn on the ignition. Due to normal circuit loading (without a short circuit), the bulb may glow dimly.

Begin to manipulate the harness (yank, tug, pull, etc.) at various locations and look for the test lamp to go bright. This will indicate that the short has reappeared.

That brown/black wire out of the j-box only goes to so many places (igniter, kill switch on the RH handlebar switch cluster, instrument cluster), so concentrate your harness manipulation in those areas. Obviously, temporarily install the tank (with the ignition on and monitoring the light) and jostle it back and forth looking for a change in lamp brilliance.

FWIW - power comes out of the kill switch as a red wire. It goes to the start pushbutton in the same cluster, and to the coils. If the switch is in the "run" position, that "short" would transfer through it back to the fuse. The coils are under the tank, so I would look very closely at those leads and their routing.

That’s the best I can offer. Good luck with it.

.

[tommu56]

If you have the wiring diagram for the bike put little larger fuse (12 amp) in and refuse each section separately with a fuse that will narrow down what section it is in.

I call these shorts a swinger because its ok until the wire moves with the wind or vibration.

tom

[D.T.]

Originally Posted by concours

This http://www.gtc.ca/EN/FF310_EN.html or the old fashioned "smoke test" . Put a really BIG fuse, or NO fuse in and look for the smoke...

Sounds like you may blow something, but then at least you will find the problem.

I say get a schematic and trace all the wires in the #3 circuit. You just have to keep at it.

[tubebender]

I'm not going to be much help, but my sons former 250 Ninja had this problem. I had to go get him more than once.

Drove us nuts trying to find the short. It was a rub through on the main harness. I'll ask him tonight if he remembers where.

[niided]

Thanks for all the replies. It sure helps to get some different ideas.

Believe me, I was at a point where I would have put in a jumper wire to do the "smoke test" but bike is in a perfect running

state now and not shorting out fuse. Right now I have it apart and going through the individual wires associated w/the ignition

circuit. Like suggested, I suspect something under the tank and up around the neck towards handle bars. Hopefully I will be

able to find the wire that is shorting out. If not. I will put things back together and try to recreate short.

Good suggestion on the test light. I will set mine up as instructed as I have gone through a number of fuses.

Also good suggestion on wiring/fusing suspect components on a direct separate line to battery. I will keep that in mind

while trouble shooting suspect components.

I will keep the board informed of my progress, or lack of. Might be hard getting any trouble shooting done today w/all the

Bowl games being played.

D.T.

[ttpete]

Look anywhere there's a chafe point, especially where the harness runs over a square or sharp edge. Sounds like the tank is pressing the harness against something and has worn through the insulation.

[tubebender]

OK, asked my son and he remembers we found the short where the harness is routed through a hook on the main frame tube under the gas tank/seat junction. There was some weld spatter there and it rubbed through.

Hope this helps.

[Warin]

Do configure a "Light Globe " fuse (as per above) ... use an old headlamp globe ... parallel hi and low beams... this should give you enough power to run the bike .. the globe might glow a pale yellow/orange but won't fully light up. When the short happens - it will light up. Another idea is to use a horn instead of the light globe ... but I don't like the sudden sound!

Take a look at the bottom of the fuel tank itself ... look for where the paint has been rubbed .. this could indicate where the wiring has been contacting the tank .. and where the wires are shorting.

The other place to check are the wires where they flex with the handle bar being turned ...

With time you will find it.

[niided]

Thanks all for the inputs.

"OK, asked my son and he remembers we found the short where the harness is routed through a hook on the main frame tube under the gas tank/seat junction. There was some weld spatter there and it rubbed through."

Thanks for checking .

"Take a look at the bottom of the fuel tank itself ... look for where the paint has been rubbed .. this could indicate where the wiring has been contacting the tank .. and where the wires are shorting.

The other place to check are the wires where they flex with the handle bar being turned ... "

I will give this shot, looking under tank for any wear marks and trying to match up w/wires.

After close inspection of wires mostly associated w/ignition circuit, I couldn't find any suspect wire. There are several wires

that are spliced together (where two or three wires are crimped to one main wire and branches off to other circuits and just

taped over) . I rewrapped these spliced spots.

I hooked up the bare harness again without wrapping the wires hoping I could recreate the short and spot the shorted

wire.

Put the #3 10a ignition fuse in turned bike on, fuse stayed intact.

Started the bike, bike ran, fuse still intact. Pulled and twisted on wires at all connections/plugs, bike still runs.

Put the tank on, bike still runs. Put pressure on tank, moved tank from side to side, bike still running.

Turned handle bars lock to lock several times, played w/all switches several times, bike still runs.

Next plan is to throw m/c ramp in back of buddy's pick-up, have him follow me while I ride, try to recreate short like it

happened the last two times. If fuse blows, hopefully it does, we will try to isolate and track suspect wire with meter right

there and then.

I will post with any success or failure. I am also thinking of investing in a new harness from Bike Bandit.

D.T.

[PeterW]

Use your nose, the burnt insulation has a distinctive smell.

And yes, wiring rubbing on frame is the most likely.

Pete