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Fuse Electrical Problem


weasel's Avatar
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06-30-03, 09:33 PM   #1  
weasel
Keep blowing fuses !

Just a hi there, I am new to the board so here I go:

A couple of weeks ago I bought a used riding mower. It is a Nome ( now Murray ) with a 12 Horse Briggs and Straton engine. The thing ran smooth and I was elated at the price. Took her home and parked it. Went to clean it and suddenly the damned thing won't start. I discovered that the fuse under the seat blew and I have been toasting them ever since. I have replaced the ignition switch ( 5 blade one ), tried disconnecting the alternator, disconnecting the starter ( I even tested that on the bench and it was fine ), disconnected the headlights, removed the solenoid and I got it to work on the bench too ... I have examined every wire ( yes even the one between the starter and the block and taped up every suspicious wire just in case there was a break in the insulation. Could the solenoid be sticking and drawing too much power and that's what's blowing the fuse ? I did test it using my car battery and I could hear it click on and off just fine. Did I miss something or do I need an exorcist ?

 
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06-30-03, 10:46 PM   #2  
The easiest way to find the short is to use an ohm meter. All you have to do is disconnect the battery and put one lead on the frame or engine block and touch the other lead on each wire until you find one that makes continuity. I have struggled with the same problem not long ago. With the newer mowers, it really gets to be a pain.

 
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07-01-03, 07:30 AM   #3  
Is the fuse blowing when you turn the key on or just when you try to start the engine?
The solenoid could be grounding out through it's housing when it's energized.

 
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07-02-03, 09:59 AM   #4  
weasel
I tried poking around with a multi-meter. I have the Briggs manual and the wiring diagrams are horrible. I have no idea which wire is supposed to do what ( although I did figure out %90 by myself ) They really need some solor coded wiring diagrams ...

BTW, As soon as I attempt to start it, it'll blow the fuse. Its fine in the "run" position.


Last edited by weasel; 07-02-03 at 10:19 AM.
 
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07-02-03, 10:21 AM   #5  
From your first post I'm still thinking that your solenoid is grounding out through it's housing when it's energized.


Ok...assuming that it's blowing after you first turn the key to the start position...
That gives you a starting point, Isolate your components one at a time (again) beginning with the starter motor and work back towards the key switch. Leave the components mounted. Try to blow the fuse as you isolate each item. While the wires are disconnected use your multimeter (key to start) and see if you're energizing a wire which may be missing a insulator at it's termination point. Hold the key to the start position for a few seconds each time to give the fuse time to burn.
If it doesn't burn after this test, I suppose it could be (though I've never heard of it) your charging system. Try disconnecting that again and see how you run.

Let us know what you find.

 
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07-02-03, 01:31 PM   #6  
weasel
The problem is, is that I have disconnected the alternator wire ( charging system ) and disconnected the starter and tried the key to start and the fuse still blows instantly. I can hear it blow. I think I am going to steal my dads solenoid ( assuming its the same ) and see if that makes any difference. Will keep you posted !

 
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07-08-03, 08:30 AM   #7  
weasel
Well I got a brand new solenoid to try ( Dad's didn't fit ). Same thing. As soon as I hit the start, boom, bye-bye fuse. I think its time to pull the whole wiring harness out. Maybe we'll get lucky and see something wrong. I am bout ready to push the damned thing into the river !!!

 
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07-08-03, 03:10 PM   #8  
weasel
Well I pulled the harness out. Tried the key and no blown fuse ! The elation was short lived, however. I realized that it would never blow, unless I start bypassing the safety switches. One the first one I tried ( clutch ) it blew the fuse when I tried to start. I am now starting to wonder if its my ignition switch ( and the damned things is brand new ) Are there different 5 blade switches ? Does anyone have a circuit diagram so I could test the switch ?

 
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07-08-03, 07:40 PM   #9  
weasel
God bless the internet ! I found that there are more than one 5 blade switch and that the new one I got is the wrong one. All I had to do is re-wire the connector and voila ! No more fuse blowing and I can hear the solenoid clicking on and off like it should. Thanks for the help guys !

 
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07-08-03, 09:36 PM   #10  
Sheesh!!!!!

You pulled the whole wiring harness??!!
At least you found the problem....good job!


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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07-10-03, 11:31 AM   #11  
weasel
Extreme problems call for extreme measures !! Besides, I was able to inspect all wires for damage ( It was easy enough to pull the wires out, took 5 min. ), and recover the wires with protective loom before it went back in. Now I can rest easy that the wires are secure and will remain in good condition. Now all I have to do is adjust the brakes and I am in business !

 
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07-10-03, 10:44 PM   #12  
5 minutes?? Must be a pretty simple harness. I was thinking of some of the more complex ones with all kinds of holding clamps and straps with a dozen or more "branches" coming off the main harness. Some of those can be a bit time consuming to remove. Good call on the wire loom. I answered the brake question in the other post.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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