Kohler 27 Courage blowing main fuse.

[LawnWizard]

Hello all,
I'm working on an old (2009) Bad Boy Pro 27 with a Kohler 27 hp. I did a longblock swap using a used longblock and the original accessories including charging system etc. Mower preformed perfectly for several hours then began blowing the main fuse. I traced the issue back to the regulator/ rectifier. Swapped that out, go to go.....for about 45 minutes. Back to blowing the main fuse again. Obviously the regulator was bad but seems to be a symptom rather than the problem. Can any of the electeical gurus out there help me sort this please? Other than a bad stator or shorted wire, what would fry the reg?
Thanks!

 

[ILENGINE]

A short that is overloading the charging system will burn out the regulator. Also if the engine has the 15 amp charging system it is a half wave rectifier. Which means the B+ terminal is linked to one of the stator wires. So a shorted stator will also cause the fuse to blow.

 

[LawnWizard]

A short that is overloading the charging system will burn out the regulator. Also if the engine has the 15 amp charging system it is a half wave rectifier. Which means the B+ terminal is linked to one of the stator wires. So a shorted stator will also cause the fuse to blow.

I'm thinking stator. On the longblock swap it was pretty straightforward. Moved stator, flywheel, coils, fuel delivery, muffler, etc from one block to the other. Does the fact that it runs fine for 30 minutes or so give you a clue as to the fault?
Thanks for the help!

 

[Tiger Small Engine]

I'm thinking stator. On the longblock swap it was pretty straightforward. Moved stator, flywheel, coils, fuel delivery, muffler, etc from one block to the other. Does the fact that it runs fine for 30 minutes or so give you a clue as to the fault?
Thanks for the help!

Check all wires both visually and with a multimeter. Check stator as well. Could be that the stator heats up with the engine temperature and is just over spec and blows the fuse.

 

[VegetiveSteam]

If it takes 30 minutes for the fuse to blow, it would be doubtful it would be the stator in my opinion. When a stator shorts it typically blows a fuse as soon as the key is turned to the on position. Maybe after the stator warms and there is some expansion, the stator wire could theoretically short to ground, but if it did, I would expect a new fuse to blow right away if you replaced it immediately.

And FWIW, if the regulator failed to regulate and was over charging, that could blow a fuse but other than that a bad regulator shouldn't blow a fuse. I won't go so far as to say it would be impossible, but it would be a real oddity.

 

[ILENGINE]

If it takes 30 minutes for the fuse to blow, it would be doubtful it would be the stator in my opinion. When a stator shorts it typically blows a fuse as soon as the key is turned to the on position. Maybe after the stator warms and there is some expansion, the stator wire could theoretically short to ground, but if it did, I would expect a new fuse to blow right away if you replaced it immediately.

And FWIW, if the regulator failed to regulate and was over charging, that could blow a fuse but other than that a bad regulator shouldn't blow a fuse. I won't go so far as to say it would be impossible, but it would be a real oddity.

I am also wondering if the regulator is the scapegoat and the intermittent short is someplace else like the fuel solenoid on the carb.

 

[LawnWizard]

I am also wondering if the regulator is the scapegoat and the intermittent short is someplace else like the fuel solenoid on the carb.

You absolutely NAILED IT! The carb solenoid wire was rubbing on the metal baffle. I couldn't see it until I moved the wire as it was pristine on top but worn through an the bottom that was resting on the edge if the baffle.
Thanks for the help!
Hugh

 

[ILENGINE]

You absolutely NAILED IT! The carb solenoid wire was rubbing on the metal baffle. I couldn't see it until I moved the wire as it was pristine on top but worn through an the bottom that was resting on the edge if the baffle.
Thanks for the help!
Hugh

Thanks for the update. I was kind of making a somewhat whitty guess and nailed it. Actually I have seen the solenoid short out or the wire cause a short and cause issues.

 

[LawnWizard]

Thanks for the update. I was kind of making a somewhat whitty guess and nailed it. Actually I have seen the solenoid short out or the wire cause a short and cause issues.

Yeah, I repaired it and used a zip tie to keep it up off the edge of the baffle. I looked at the rest of the harness for possible trouble spots then moved and zip tied anything that looked like it could rub.
Thanks again.