Super mta electrical issues

[Eastern shore farmer]

Finishing up my super mta project today and installed
wiring and alternator. Everything worked fine for a while
until I shut it down and started it back up and only firing
on two cylinders, charging 15.xx volts. Amp gauge is
pinned and will run if I disconnect battery cables. Dont
understand whats happening im obviously over looking
something. This 1 wire alternator has previously been on
this tractor about a year now and no issues until today.
Any idea whats going on?

 

[Janicholson]

It is likely that the regulator in the alternator has failed. Alternators need a battery to correctly judge charging voltage. Never disconnect the battery when running as that can allow radical voltage to be created which then fries the electronics in the regulator. with a charged battery the voltage should never be above 14.6. Pegged amps and high voltage can't be fixed without checking the Alternator in town. I believe in the use of 3 wire (actually 2) with a amp gauge with more amp rating than the alternator, a marker lamp ot 10 ohm resistor, or a diode in the wire going to the ignition switch. #1 terminal connected to the ignition, #2 connected to the output stud (6 inches long), and the main output going to the larger amp gauge. Delco 10SI is very inexpensive.
The misfire may be unrelated, such as the wires in the cap wrong. 1342 from front with #1 at top right looking from the rear, and going clockwise. Jim

 

[Bob M]

I agree with Jim 100%! A couple more points:

NEVER disconnect the battery on alternator-equipped equipped machine with the engine running. Otherwise there's a high probability of frying the internal regulator or destroying the alternator diode pack. (Been there, done that....!)

Also.....if the battery is less than fully charged an ammeter pegged on the + side is of no concern. It simply indicates the battery is charging. Then as the battery approaches full charge the rate will taper to 2 - 4 amps or so.

Re the missfire: Sounds like the plug wires somehow got reversed between the two dead cylinders. Try swapping at the distributor cap and see if they dead cylinders come back.

 

[used red MN]

The other replies covered the alternator issue so let me comment on your misfire. I dont no how familiar you are with these old Farmall 4 cylinders but as a rule they need very little choke when the carb is set right. When starting it pull the choke on and roll it over about 2 or 3 times. Let off the starter and push the choke back in, wait a couple seconds for the gas you pulled in the carb to vaporize a bit. Then hit the starter and she will fire right up. Then idle it a bit and it may want to die off so give it another quick out and in with the choke to keep it running. Then after a bit if you want to move the tractor when you put it in gear and let out the clutch if it wants to die give it another quick out and in of the choke. After two or three minutes of running you will no longer need any choke. If you are one of these guys that likes to run half choke while warming up an engine do not practice that with these old 4 cylinder Farmalls. Now here is the reason, running rich like that fuel fouls the plugs with black soot. Then it is very hard to get the plugs to self clean after that. This is especially true due to the light use most of these tractors see. It was not so much of a problem when you took them out and worked them hard the plugs would then clean off. So after all that, I think if nothing else was messed with on the ignition the above may be a possible cause of your misfire.
What did you find out with the gears in your 450? Maybe your focus has been on this tractor. Super MTAs are nice, I wish I had one.

 

[BarnyardEngineering]

It's really tough to screw up the wiring on a one-wire alternator. There's only one wire, which runs from the terminal on the alternator to the "load" side of the ammeter. That's it.

If the ammeter is pegged the alternator's regulator has probably failed. Unhooking the battery is not a valid test for anything and as others have mentioned, potentially fatal for the alternator. So if it wasn't bad before it's probably toast now.

With the misfire first step is to figure out which cylinders are misfiring. Pull plug wires one at a time. When the engine doesn't change how its running that's the dead cylinder. If it turns out to be 2 and 3, my guess is you swapped the plug wires by mistake.