Lawn Tractor Main Fuse keeps melting

[WestyFan]

Hi i was wondering if anyone could help me.

I have a Countax diesel lawn tractor model number D1850

The main fuse keeps melting but not blowing every time I start the tractor. Loads of smoke pours out of the dash. When the engine starts it stops smoking. Does anyone know what the common causes are for this problem?

It currently has a 30amp blade fuse in it.

Any help will be greatly appreciated.
I have attached a photo of under the dashboard but it probably won't help much, it's just to show you what it looks like.

Thanks

 

[joester]

What exactly is smoking, the fuse?

I had a similar issue with my Honda Motorcycle and it ended up being that the wire connections to the fuse holder were loose. The heat was caused by current flowing through only a portion of the wire strands..

 

[WestyFan]

What exactly is smoking, the fuse?

I had a similar issue with my Honda Motorcycle and it ended up being that the wire connections to the fuse holder were loose. The heat was caused by current flowing through only a portion of the wire strands..

Thanks for the reply. Yes the fuse gets very hot and the plastic melts but the fuse doesn't actually blow. I even plugged a different fuse holder into there and the same thing happened. The connection seems good that is why I am so confused about this issue.

 

[reynoldston]

So what you have is something drawing more then 30 amps. Short in the wiring, starter system? I would say find the problem before you do some real bad damage. Start with a wiring diagram and follow back from the problem fuse till you find the trouble.

 

[bertsmobile1]

You have a short in the wiring system.
Nothing in the ignition system should draw more the 5 amps.
If it goes away when the engine is running I will hazard a guess ( don't have your wiring diagram ) and say the generator is back feeding .
Disconnect the generator and see if the fuse stays cold.
The only connection that usually changes, engine running to igniton on & ingine not running is the power from the generator

 

[joester]

I disagree with the "short" analysis, or the fuse would blow.

My reference is to where the wire is crimped on the back of the fuse holder. If several strands of wire are not properly crimped or have broken then the current being drawn through the remaining strands will cause them to get hot. Heat transfers through the blade portion of the holder and into the fuse. The fuse, being soft plastic, melts but the fuse does not blow.
You need to remove the fuse holder and inspect the back side of it where the wires are connected. My bet is you will immediately see the suspect wire with melted insulation and careful inspection will reveal what I'm talking about.

 

[bertsmobile1]

I disagree with the "short" analysis, or the fuse would blow.

My reference is to where the wire is crimped on the back of the fuse holder. If several strands of wire are not properly crimped or have broken then the current being drawn through the remaining strands will cause them to get hot. Heat transfers through the blade portion of the holder and into the fuse. The fuse, being soft plastic, melts but the fuse does not blow.
You need to remove the fuse holder and inspect the back side of it where the wires are connected. My bet is you will immediately see the suspect wire with melted insulation and careful inspection will reveal what I'm talking about.

Stand corrected, short was the wrong word .
I am thinking more along the lines of a diode failure and the alternator trying to become a starter motor.
This draws a lot of power while stationary but once rotating it goes back to being an alternator.
Sometimes you can ask get AC back feeding into the loom which will also melt wiring but not blow a fuse.
SO the actual melting can be occuring while the engine is running and when not running the fuse gets hot due to continuious sub critical current draw.

And yes it might be as simple as broken wires at a connector except that there should be no current draw with the ignition in the ON position and the motor not spinning unless there is a diode failure or a short ( partial ) in the loom downstream of the fuse.

 

[joester]

AC backfeeding could be a contributor, but I couldn't help but think that if enough current is being drawn to melt the fuse, that the fuse itself would blow. That's why I lean towards a failing crimp at the fuse block. It wouldn't take much current to generate heat which could melt the softest plastic in that area (the fuse).

I did a little looking into fuses and ratings, and was surprised to find that in one case a 23amp load was sustained through a 10 amp fuse. They had to ramp up the load in a very controlled manner, but it does open up the possibility that a failing fuse, alternator, regulator, ect... can also cause the symptoms the OP is having.

I would start simple and carefully check the wires (look for discolored tabs where the fuse makes contact and/or damage to the insulation on the wires), then look into the alternator. Probably have to take it to the dealer for checking. I doubt Autozone/Advance Auto/ect.. would have the fixture for it.

I hope I'm right and you're wrong... Not for my ego, but in consideration of the cost/ease to repair.