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Hi,
I have a friend who has a Troy Bilt riding mower 13AP60TP766 Horse (2006).

It starts OK, but after running a minute or two, blows the 20 amp fuse.
On the flip side, it doesn't blow the fuse if it's just powered up without the engine running.

I'm having trouble finding a wiring schematic for that model to properly test the wiring.
I have the feeling it's a re-branded Cub Cadet model of some kind, but I don't know which.

We've done a thorough visual examination and can find no wiring problems.
But without a wiring schematic of that model it's difficult to go further.

Any advice would be appreciated. :smile:

As it only happens when the engine is running then it has to be connected to the alternator.
No 1 suspect is the rectifier pumping raw AC back into the engine.
Check the middle wire of the rectifier for voltage to ground, engine running.
Should be 12 to 15 V DC.
Then check it for AC, should be 0 V

OK thanks.
We'll check it.

I am experiencing a similar issue, 3 weeks ago my troy built bronco, (same model #) was fine. Been trying to find out now why the fuse keeps blowing when i crank it. Seems like a dead short somewhere.

In our case, my friend told me he measured voltages like described in Post#2.
He found AC voltage on the center tap of the Rectifier-Regulator.

In my last communication with him he was looking to buy a replacement Rectifier-Regulator and a new battery (as the battery won't take a charge).

I advised him to be sure the new battery is charged up before starting the mower, so he doesn't take a chance on straining the Rectifier-Regulator.

I'll report back again when I hear from him having replaced the parts.

If the rectifier bolts into the plastic blower housing make up a pair of ground straps and ground it at both sides to a different bolt on the engine.

The grounds break or corrode then you get a high resistance which pushes up the amps higher than the diodes can handle

bertsmobile1 said:

If the rectifier bolts into the plastic blower housing make up a pair of ground straps and ground it at both sides to a different bolt on the engine.

The grounds break or corrode then you get a high resistance which pushes up the amps higher than the diodes can handle

Click to expand...

The picture my friend sent me the Rectifier-Regulator looks to be bolted into a metallic surface.

edporch said:

The picture my friend sent me the Rectifier-Regulator looks to be bolted into a metallic surface.
View attachment 38813

Click to expand...

Those ones have to come out every now and then and clean off the corrosion because water will pool around the case, the case is zinc & it is bolted to steel so you will get galvanics when they get wet.

bertsmobile1 said:

Those ones have to come out every now and then and clean off the corrosion because water will pool around the case, the case is zinc & it is bolted to steel so you will get galvanics when they get wet.

Click to expand...

Thanks, I just passed this on to my friend.

Is this to help improve cooling?

Would a wire brush work for cleaning?

soft ( brass ) brush is fine, I soda blast now days.
And yes it is for cooling rectifiers generate a lot of heat.

bertsmobile1 said:

soft ( brass ) brush is fine, I soda blast now days.
And yes it is for cooling rectifiers generate a lot of heat.

Click to expand...

Thanks, I passed this on to him.