860 backfire and alternator fuse

I was running the tractor today raking some pastures and parked it to do some other tasks. I went back about 6 hrs later to put the tractor up and it started backfiring really bad and then came hard to start, finally, just not starting. It had been running pretty good otherwise, seems like something happened all of a sudden.
On another item, the wire from my alternator to the solenoid that charges the battery has a fuse in it (30 amp) and it keeps blowing. Is that too small or should I use a circuit breaker type fuse or does it need a fuse?
 
Backfire could be a carb problem and running lean or a sticking valve or a valve that needs to be adjusted. Fuse in that circuit should not be there at all. Common rate of charge of an alternator is 35-75 AMP if not higher
 
Check your spark. Often backfiring is caused by unburned fuel from one cylinder being in the exhaust when the next exhaust valve opens which then ignites the unburned fuel. Hard starting followed by not starting is another clue. Put in new points and your problem is likely to go away.
 
It is unusual to have a fuse in the line from the alternator to the battery. Your alternator is likely to be a 60 amp and a 30 amp fuse just cannot handle the current when charging the battery. One of my pieces of equipment with an alternator has a 30 amp gauge and at startup when the battery has been drained a bit from starting the gauge pegs the needle for a minute or 2 as the alternator recharges the battery.
 
It is not clear to me from your post. Did you find the alternator fuse was blown? If so did the back fire go away after replacing/eliminating the fuse? As noted by another poster back fire can be caused by weak spark. Once the fuse blows, the system voltage drops from charging voltage (14.5) to battery voltage (12.6) approximately. As the battery discharges, the voltage continues to drop. As the input voltage to the coil is reduced, at some point, the spark becomes
weak.
 
okay... sounds like the fuse blew.. and the battery got run down and it started misfiring and finally cut off... SO... charge the battery.... fully for a couple of days. Second the alt fuse should be 60 amps or more pending on the alternator you are running. Most tractors DONT have a fuse in this high current line. Since the 860 was a conversion from probably a 11 amp generator, make sure the alternator charge wire.... is sized correctly for a high current alternator,,, so you dont melt this wire and start a fire. Should be a minimum of 10 ga wire. Most generic replacement alternators start at 65 amps now days. Start tractor and as the alternator is now charging the battery again, life is good.
 
I will take the fuse out and charge the battery and report back. Sometimes it wont start in a normal way. What I mean by that is when you have the key in the start position, and the motor is turning over, it doesnt crank until you let go and it goes to the run position. I think, this may be related. It has been converted to 12 volt with the GM alternator.
 
I will take the fuse out and charge the battery and report back. Sometimes it wont start in a normal way. What I mean by that is when you have the key in the start position, and the motor is turning over, it doesnt crank until you let go and it goes to the run position. I think, this may be related. It has been converted to 12 volt with the GM alternator.
 
The 30 Amp fuse is not large enough to carry the alternator current at startup when the battery is run down and the alternator charges heavily to fill it back up.

Having a fuse in the alternator output circuit blow when it's charging heavily is NOT a good thing and may damage the alternator and/or the voltage regulator.

However, having circuit current protection in the charging circuit is NOT a bad idea, in case the alternator ever fails/shorts.

Replacing the fuse with a 4"-6" length of 14GA FUSIBLE LINK WIRE would be a GREAT idea.
 
If I understand correctly you have a key switch that has 3 positions: Off = no power to ignition coil or starter solenoid, Run = power to the ignition coil.
Start = power to the ignition coil plus power to the starter solenoid. From your post it sounds like there is no power to the ignition when the switch is in the start position. You can check this with a test light connected to the battery side coil terminal. The test light should light with the key switch in the run position and remain on in the start position. Or, you could remove a spark plug and lay it against the engine - watch for spark as the starter turns the engine.
 
As someone posted replace the fuse with a fusible link wire. good parts stores sell them with a ring terminal on one end already.
It sounds like your ignition switch might be the problem or at least where I would start looking.
 
I will check that when I am at the tractor again. I need to check the ignition switch wiring definitely. There is something different with it over my NAA.
 
Update: Took battery charger to the tractor today and charged the battery. It was not low as the charger barely registered any amperage, however I left it on for an hour or so. I removed the fuse and replaced it with a 4 fusible link. The 30 amp fuse was blown. I then replaced the fuel filter and cleaned out the glass bowl. It cranked and didnt backfire and was fairly smooth. I noticed the volt meter on the tractor was right at 12 volts at idle until you rev it and then it jumps to 14 volts. When you idle it back down it stays at 14. I thought that was odd. The alternator on it shows Delco-Remy with a K stamped on it if that means anything..
Thanks for the tip about the fusible link. That fuse has really caused me a lot of headache.
 
(quoted from post at 17:42:21 04/30/22) Update: Took battery charger to the tractor today and charged the battery. It was not low as the charger barely registered any amperage, however I left it on for an hour or so. I removed the fuse and replaced it with a 4 fusible link. The 30 amp fuse was blown. I then replaced the fuel filter and cleaned out the glass bowl. It cranked and didnt backfire and was fairly smooth. I noticed the volt meter on the tractor was right at 12 volts at idle until you rev it and then it jumps to 14 volts. When you idle it back down it stays at 14. I thought that was odd. The alternator on it shows Delco-Remy with a K stamped on it if that means anything..
Thanks for the tip about the fusible link. That fuse has really caused me a lot of headache.

THANKS for the report back!

I hope you used a 14ga, fusible link, a 4ga would be awfully large!

Is this a "one-wire" alternator?

That's how they act, the engine needs to be revved a bit to "excite" them, then they will continue charging at a lower engine speed.
 
If this is a duplicate, I apologize.I tried to edit and not text shows on my end.
I used a 14 gauge 4 inch fusible line. It had a ring connection on one end and I attached that directly to the alternator. I then just spliced the other end into the lead wire to the battery. I bet I popped 20 fuses and I never thought about a fusible link! I am glad the old days at the pick and pull were used to pull fuses from the scrappers
 

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