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Author Topic: blowing main fuse  (Read 1137 times)

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jjones

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blowing main fuse
« on: October 29, 2011, 12:58:01 AM »

I have a 78 kz650sr been sitting for years i got it running runs good.It started blowing the 20a main fuse 3 weeks ago i have traced every wire on the bike cant find a bad wire any where checked my coils they are good just changed the bars yesterday didn't find any bad wires when i removed them from the old bars i rewired the fuse box to the blade fuses its been a intermittent thing with the blowing fuses til 2 days ago i went for a ride got a 100 yard from home and the fuse blew and blew every time i replaced it and turn the key switch on yesterday i replaced the fuse and turned it on and it didn't blow the fuse didn't try cranking it cause was in the process of replacing the bars tonight wrapped that up tried to crank it i run the battery low trying to start it cause it would fire and die kicked started it til i was exhausted then left it alone for about a hour the tried it again it fired up ran a min then died no power it blew the fuse again i am at a lost i have gone over this bike everyday for 3 weeks looking for the problem cant find anything.I need help this bike is driving me crazy its become my Nemesis.I have been a mechanic for 20 years never had a problem i couldn't find and fix.I an ready to burn it to the ground!!!!!
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Charlie

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Re: blowing main fuse
« Reply #1 on: October 29, 2011, 06:23:33 AM »

Check the horn wire (brown if I remember correctly) is not grounding to the frame where it feeds through the down tubes. It is a common cause of the problem you have.

Beyond that, it's often the handlebar switches that are earthing out to the bars ...
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rstnick

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Re: blowing main fuse
« Reply #2 on: October 29, 2011, 11:24:23 AM »

Something is grounding out that shouldn't.
I'd suspect a wire touching the handle bars as you've switched them.

I had a fuse blowing problem some years back that was caused by the headlight shell.
One of the white plugs inside was really close to the rear opening of the headlight shell, and when I turned the handle bars, the white plug would touch the edge of the headlight shell and blow the main fuse.
I wrapped the plug in electrical tape and I was on my way.

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Rob

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'78 C2 Candy Apple Blue, 103 500 kms, 18" wheels front & back, Rickman fairing, Koni shocks, Progressive springs, braced stock swingarm, GSXR600 rear sets, ATK fork brace, SS brake lines, Kerker exhaust, K&N filter in air box, ported, 1st over bore, Kawi electronic ignition, bought in '84.
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Victory402

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Re: blowing main fuse
« Reply #3 on: October 29, 2011, 11:32:41 AM »

It's a ground or a short in one of the circuts feeding off that fuse. If possible, try disconnecting or unplugging different items one at a time, like your rear light harness or horn until the problem goes away. Another thing to do is pull one of the other 2 fuses one at a time. Obviously you cant disconect the power feed to the coils. I looked at the schematic and the wire feeding off of the main fuse goes up to your ignition switch first, this is a good place to start. You mentioned that you inspected all the wires, good, That means its more than likely a device, ie; headlight, handlebar switch. Take it one device at a time. Diconnect it, run bike for a while. ect. With intermitant electrical problems like this on a vehicle it's often vibration causing the short or ground in a wire or a device. Since I'm new at the kz650, I would wait for one of the experts here to chime in. hope this helps a little til then.
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jjones

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Re: blowing main fuse
« Reply #4 on: October 29, 2011, 03:34:20 PM »

I found the regulator rectifier is bad got very high readings on 2 of the 4 tests on it and nothing on the other 2 on the forward bias i am going to replace it and i am also going to check the ignition switch to make sure its not bad hopefully this solves my problem.
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deadpool126

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Re: blowing main fuse
« Reply #5 on: October 29, 2011, 04:19:41 PM »

i had the same problem it was the wires under the push start got clipped when i was screwing it back on i found out by unplugging one harness at a time then turning key after i figured i just trced the wires took me 5 min to fix
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jjones

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Re: blowing main fuse
« Reply #6 on: November 02, 2011, 11:24:42 PM »

i found i had a bad rectifier changed that got it running now it is blowing main fuse again when i rev it up.my kill switch doesnt work any more it will start and stay running whether it is in run or off i am stumped with this bike i am frustrated with iti dont like pushing the heavy ass thing i want to ride it again i need help
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Jefferson

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Re: blowing main fuse
« Reply #7 on: November 02, 2011, 11:40:48 PM »

i would re-wire the connections to and from the regulator.  i had a similar issue where the wires inside the connector going to the regulator were burnt up and either battery would not charge or fuse would blow. 
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Jeff
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gd4now

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Re: blowing main fuse
« Reply #8 on: November 03, 2011, 01:03:15 AM »

I know it is not what you want to hear but it would appear that something is shorting to ground and pulling more than 20amps and blowing the main fuse. From your post it sounds like you have looked at all of the wires and connectors changed the fuse box and the reg/rect unit. But I would take a look at the run stop switch that is no longer working.  Since it is passing voltage even when set to off it may be shorting our.

If you think the issue is related to the reg/rect unit then unplug the red/white wire from it to the battery.  The bike should run without it connected, it just will not charge the battery. If the fuse does not blow then it would appear the issue is with the new unit or its connections. If it does blow then it would appear that the new unit is not the issue. I have attached a text document I pulled from another forum on how to test for shorts that you may find of use.
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Bruce
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