Why would a mower melt 20 amp fuses?

[EddieWalker]

I have a Scag Wildcat zero turn with a Kawasaki liquid cooled 26hp engine. All of the wiring diagrams for it leave the engine out. I can't even find anything that says what start is has.

One of the odd things is that since this started happening, the water temperature gauge isn't working. For some reason, I think this is important.

I can mow for an hour, two hours, and one day, 3 full hours, without issue. But I have more days where I can only go for 20 minutes and the fuse melts. It doesn't just blow, the plastic around the fuse melts. The wires going to it are super hot!!!!! I've replaced the fuse and mowed for another half hour, ten minutes or a full hour, before it happens again. I've had days where I've replaced 4 fuses to finish mowing. But now it's getting worse. A lot worse!!!!

I traced every wire looking for a wear spot that might indicate a short. I've done this 5 different times and haven't found anything. Sometimes after doing this I can mow for hours. Today it was ten minutes and this is what the fuse looks like.



I'm starting to think that it's not a short, or a wire with a bare spot that's touching the frame somewhere. I'm starting to think that there is too much electricity going through the wires. My only guess is that my PTO Generator is overcharging and putting out more then 12 volts or more then 20 amps. The only time this happens is when the PTO is engaged and I'm cutting grass. I'm not comfortable putting a volt meter on it with the PTO engaged, but that might be my only option. I'll just have to be careful.

Something else that I noticed was that when I put my meter one of the two wires coming off of the PTO Generator, and tested for continuity to the frame and the engine, I didn't get anything. But when I put the meter on both wires, I did get continuity. Should that happen?

Is there something that I'm missing?

What else could cause this?

Is there a way to adjust the voltage coming from the PTO Generator?





Thank you

 

[Midniteoyl]

PTO Clutch coil going out?

 

[RandyT]

Unplug the pto clutch and check the ohms of resistance on the clutch. Should be in the area of 2.5-3.5 ohms. There should be continuity between the two wires coming from the stator under the flywheel. There should be no continuity between either stator wire and the engine or the mower frame. Continuity to ground would indicate a shorted flywheel stator.

Also need to make sure that the contact terminals in the fuse holder are not corroded. Resistance at the fuse holder would cause the fuse to melt.

 

[LittleBill21]

what is a pto generator? do you mean a pto clutch?, get an amp clamp, and measure the amperage. pto clutch is a coil, it will have resistance.

 

[EddieWalker]

PTO Clutch is probably the correct term. I thought it was a generator because it also charges the batter. Or does it?

I'll have to do a search on YouTube to learn how to check the ohms of resistance on the clutch. That will give me some good keywords to use in my search.

I'll look at the contact terminals on the fuse holder.

Thank you!!!

 

[LittleBill21]

PTO Clutch is probably the correct term. I thought it was a generator because it also charges the batter. Or does it?

I'll have to do a search on YouTube to learn how to check the ohms of resistance on the clutch. That will give me some good keywords to use in my search.

I'll look at the contact terminals on the fuse holder.

Thank you!!!

the pto clutch does nothing more then engage the blades.

the stator is built into the engine and works off the flywheel which has magnets, this is what charges the battery. this flywheel is also what fires the magneto ignition (based on a B&S motor)

 

[Topzide]

Sounds like pto clutch about to go belly up. Charging is under flywheel. That's what's called a stator. Only puts out 3 - 15 amps tops. If pto clutch does die or find its the problem, replace the pto switch also. Better to do at same time to avoid more issues. Good luck.

 

[EddieWalker]

Thanks. I replaced the PTO Clutch a few years ago. How long should they last? I forget why I replaced it or what it was doing. I've also replaced the switch for it 4 times so far.

Scag makes a very strong, heavy duty mower with the very worse electrical system I've ever dealt with!!!! Every safety sensor has been bypassed. I've lost more days then I can count just trying to get it to start because of a bad sensor.

 

[BleedingOrange]

Take the clutch off, and check the bearings in the clutch. What might be happening is, if the bearings are starting to bind, or if you lost some of the balls from the damaged bearing, sometimes they might align enough to allow the clutch to turn freely, and other times they might bind enough to blow the fuse.

 

[KWentling]

I would think you would have to have a poor high resistance connection to melt a fuse like that. probably the fuse holder itself. But then you have tissue of blowing the fuse too. Possibly turn to turn short in the clutch coil causing higher than normal amp draw.