Need guidance on why my fuel gauge got scorched

[MA1920]

The ground wire in the picture looks like it has been undisturbed for a long time. Disconnect it from the engine, shine the ring terminal and the metal it contacts, apply a light film of vaseline or dielectric compound and tighten it down. Carefully check the resistance between the battery negative post and the engine. It should ne zero, clean it the same as stated above.
I should have as this at the outset; had the gauge worked before it smoked. What if anything had been done to the tractor just before it smoked. I have doubt that the sender was the cause but it is possible. There may be a gauge voltage regulator just for gauges that is faulty. You did mention that one of your other gauges was inoperative but not burned I believe. I don稚 recall seeing a regulator in your wiring diagram but it would be a good idea to carefully check for one. We will solve this mystery, hang in there.
Smilinjak

I cleaned the terminal, but didn't apply any dielectric grease. I'll do that. The temp gauge also doesn't work, stuck on cold, but doesn't show any sign of electrical overload. The only other "issue" the tractor has is I have to do the ole jiggly-wiggly with the forward-reverse lever to find the sweet spot in neutral, then the tractor will instantly turn over and start. That's probably the neutral safety start switch approaching retirement age and shouldn't affect anything else.

I asked my sons if they can think of anything not working properly. They reminded me of the time a battery charger was connected to the battery backwards. They were charging the battery with a low amp charger, I think it was 6 amps. As soon as the alternator started smoking and stinking "a little" (their words) they disconnected the charger.They said they told me about it, but I don't remember. Sounds like me when I was their age.:shocked:

The voltage regulator is part of the alternator assembly. Could it have been damaged by charging the battery incorrectly for a short time? Could that have damaged the fusible link? We might be approaching a conclusion...?..maybe.

 

[smilinjak]

The alternator voltage regulator is a separate device from the instrument regulator which you may not have.
The reversed charger incident is the key to your electrical woes. The alternator is probably toast. Take it off, take it to O’Rieleys or Autozone and have them test it. They probably won’t have a replacement if you need one but you will know if it is good or not. Yours could be putting out very high voltage. The internal regulator is very suspect. In the future disconnect the ground cable before hoohin up a battery charger to isolate the tractor electrical system from the inadvertent reverse charger hook up. Figure to replace the temp sender and gauge along with the fuel sender and gauge. I’m afraid the incident is going to be a very expensive mistake.
Get back to me on the outcome of the alternator test
Smilinjak

 

[MA1920]

Just got back from Autozone and the alternator is bad. Now, the question is $263 for one from NH or $75 for aftermarket from Amazon www.amazon.com/ALTERNATOR-FITS-TRAC...jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ== Is there a major quality difference between OEM and aftermarket? I would prefer to stick with OEM but that's a substantial difference.

On closer inspection it appears that the back of my original is a little different than the one from Amazon. Is the extra plug in terminal on the right hand side of the Amazon one only used for some tractors? Thanks.

 

[smilinjak]

The after market alternator is most likely chinese and has multiple applications. If you don’t have a wire to plug into it don’t worry about it as long as it has the socket for your 2 wire plug. For the difference in price you can buy a couple of cases of blue paint to make it match. The NH unit is probably made in the same Chinese factory as the after market one. I think you have found the cause of your problem. Get all the gauges, senders and fusible link gathered up and proceed with reassembly. Your fuel sender is probably OK but to be on the safe side replace it. Same for the temperature sender. If the oil pressure gauge is electric replace it’s sender as well. Fuel level accuracy is not critical but oil pressure and temperature are. Keep me updated as you progress please.
Smilinjak

 

[MA1920]

Time for a quick weekly update. The new alternator is in, the new fuel gauge is in and I reassembled the instrument panel. I'll start putting sheet metal back today. I'm getting a fuel sender this week.

 

[smilinjak]

Time for a quick weekly update. The new alternator is in, the new fuel gauge is in and I reassembled the instrument panel. I'll start putting sheet metal back today. I'm getting a fuel sender this week.

Glad to hear that you are making progress.
Smilinjak

 

[ruffdog]

When I see multiple items fried, I immediately check the rectifier for the alternator to see if the diodes are bad. Diodes are one-way switches that change a/c currant to d/c because it can only flow one direction. When a rectifier goes bad, high (maybe 75 a/c v) current goes through anything that is turned on. That would include gauges, ign controllers, lights, radio, regulator, etc.

I have seen people replace hundreds of dollars worth of electrical components, only to fry them again as soon as the engine starts again.

 

[smilinjak]

When I see multiple items fried, I immediately check the rectifier for the alternator to see if the diodes are bad. Diodes are one-way switches that change a/c currant to d/c because it can only flow one direction. When a rectifier goes bad, high (maybe 75 a/c v) current goes through anything that is turned on. That would include gauges, ign controllers, lights, radio, regulator, etc.

I have seen people replace hundreds of dollars worth of electrical components, only to fry them again as soon as the engine starts again.

I think we got that covered with the new alternator. I had you revelation come to mind after stumbling around for a while. Thanks for your input.
Smilinjak

 

[MA1920]

When I see multiple items fried, I immediately check the rectifier for the alternator to see if the diodes are bad. Diodes are one-way switches that change a/c currant to d/c because it can only flow one direction. When a rectifier goes bad, high (maybe 75 a/c v) current goes through anything that is turned on. That would include gauges, ign controllers, lights, radio, regulator, etc.

I have seen people replace hundreds of dollars worth of electrical components, only to fry them again as soon as the engine starts again.

The rectifier is internal to the alternator. Is that normal? When I had the alternator tested it failed every test.

If you're having trouble sleeping you can skim over all five pages of this thread. If you manage to stay awake you'll realize that me and electrical diagnosing have a tumultuous relationship. After reading every comment several times and continued studying of the wiring diagram, we're not quite friends yet, but diagnosing and me are at least approaching being tolerant of each other. The next step may be friendship.:dance1:

I appreciate your comment, it added to my ever increasing knowledge of wiring. Thanks again.

Bob

 

[ruffdog]

Internal rectifier? Yes, normal for a belt driven type alternator. Glad you tested it before more damage was done.