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MikeT

new to forum keep blowing 25 amp main fuse

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First I would like to say hi to all, I am new to this forum and there is a wealth of info here, I have a 1986 314-8 that has been bulletproof since the day I bought it, just recently it started blowing its 25 amp main fuse, it only blows when I turn the key to the run position , turning the key to the on position does not blow the fuse. if I jump across the solenoid the starter spins but it does not engage the flywheel. turning the engine over by hand I can hear some rumbling coming from the starter and only once after turning it over by hand was I able to start it with the key without blowing the fuse. Is it possible that the starter is bad and creating the dead short? From time to time I would hear the starter drag a bit before it would fire, but not all the time. The battery is new and the charging system is working or at least it was before this. I can hear my grass growing as we speak, HELP.   

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I just picked up an '86, 417-8 that was having the same problem. the PO had put in a new solenoid, and key switch and gave up trying to fix it.

 

I looked and found the solenoid was just sitting there kind of loose on one bolt and the battery cables were not all that tight either.

 

snugged everything down and problem solved!  :)

 

I would check all the grounds ;)

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if you have any starter drag at all it takes that much more juice to move it creating heat and friction and resistance and resulting overloading the circuit and blowing fuses in a lot of cases......but anyways check all your wiring back to the starter and solenoid and battery check all connections thoroughly start at the ignition and check for anything bare or chaffed showing through then if you can't find anything from there take the starter right out and bench test take apart clean it up if you can take some emery cloth clean up the armature or the area where the brushes rub make it shine also check the bearing too make sure its not binding

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Im going to give everything the once over, nut and bolt all grounds, see what I can find, What stumps me is the one time I turned the engine over by hand clockwise and counter clockwise it seemed to free up if that makes sense and it fired with a turn of the key. I tried the same thing again and continued to blow fuses. I need to get this machine working again. I really shouldn't complain, its been a workhorse all these years. 

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Certainly check all the wiring and grounds as stated above.    If you have suspicions there is something catching and rubbing the flywheel and / or starter, I would pull the starter and tin off to check this out before attempting to start it.

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There was no 314-8 in 1986 so must be a 1985 model with a 3 amp unregulated charging system. If so here is a wiring diagram you can download.

Garry

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Posted (edited)

A starting circuit draws more than 25 amps so the fuse that's blowing is un-realted to the starter itself. You have a short. Could be in the solenoid if it only happens when the key is turned to start. Most likely the wire from the key switch that runs thru the safety switches to the solenoid is chafed somewhere. A bad ground will not blow a fuse unless what's badly grounded ends up grounding thru something else that's connected to the fuse. The diagram Gary provided shows a 15 amp fuse in the circuit. If the diagram is correct someone put a bigger fuse in trying to solve a problem. The starter current is all handled by the battery cables. They are capable of handling 200 amps so I think you have a starter motor problem (noise) and a starter control (small wire from switch blowing the fuse) problem.

Edited by squonk
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10 hours ago, MikeT said:

First I would like to say hi to all,

 

:text-goodpost:

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7 hours ago, gwest_ca said:

There was no 314-8 in 1986 so must be a 1985 model with a 3 amp unregulated charging system. If so here is a wiring diagram you can download.

Garry

Garry, that diagram doesn't have a 25 amp fuse in it

10 hours ago, MikeT said:

if I jump across the solenoid the starter spins but it does not engage the flywheel

Mike,   :WRS:   The bendix drive on your starter could be in need of cleaning and a bit of graphite lubrication (don't use oil)!

When looking for for a short I use a 12 volt test light in place of the fuse. As long as the short is present the light will continue to be illuminated, when you clear it the light will go out.

There was a 314-8 in 1993, here is the manual

 

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Based on a quick examination of the diagram I would begin by unplugging the voltage regulator.

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With the 93 diagram it's possible the starter could back feed thru the fuse. Unhook the starter positive wire and turn the key. If the fuse doesn't blow there is your problem. When the soleniod engages the fuse is tied into the main start curcuit.

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I would like to thank all of you for your comments and suggestions, all are invaluable, I have to say this forum is unlike any of the others I have joined for information. Anyway, I took the starter out and took it apart, cleaned it up and used a dri lube when I put it all back together , I removed all the tins and I cant believe the amount of crud there was behind it all, I took the opportunity to give the tractor a much needed once over and I am very happy to report that it fired right up at the turn of the key, no noise from the starter no drag just a healthy whir of the starter spinning the flywheel, now as to the year of this tractor, I bought it from a buddy of mine in 1989 with 20 hours on it, I thought he said he bought it new in 1986, I was wrong it was 1985. again I would like to thank all for your comments.

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Thanks for the update Mike......we luv it when a plan comes together.

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