Ford 861 runs like crap!

Ford 861 Powermaster; was running fine then started sputtering. Cleaned sediment bowl and screen then ran fine again. Let it sit for about an hour then started it up again and it was sputtering badly, occasionally puffing black smoke. Has new points; they look fine. Checked and cleaned plug wire contacts. Could it be fouled plugs? (Was converted to 12v years ago and has been running fine). Can send short video of tractor running and sputtering/puffing black smoke.

Do some simple trouble shooting.
#1 check that you have a good blue/white spark that will jump a 1/4 inch gap or more at the center wire of the cap and at all 4 plug wires.
#2 pull the carb drain plug and make sure you have a good steady flow of gas that will fill a pint jar in less then 3 minutes. Yes catch the gas to look for water/dirt.
#3 when was the last time you serviced the air cleaner and dumped the water and mud and fill with fresh oil?

I actually did all that and have good spark, no water/mud and great gas flow.

Black smoke is generally from too rich, as in flooding carb, choke not fully open, clogged air cleaner.

If it was run too rich the plugs may well be fouled. Inspect, clean or replace accordingly.

Disturbing the fuel strainer could have released some trash that found it's way into the needle/seat. It only takes a tiny speck.

Try turning the fuel off, remove the carb drain plug, then open the fuel valve. This will let the needle valve fall open fully, the flow of fuel may wash out anything caught in the needle valve. Catch the flow that comes out the drain in a clean glass, there should be a steady flow, not a drip or no flow. See what is caught, should be clean, free of rust, dirt or cloudy with water.

If it continues to run rich the carb will need to come apart. Don't be afraid of it, they are simple and repairable, better than the new replacement aftermarkets.

Check the float for fuel inside one of the pontoons. Check the float level. Check the needle/seat for a good seal. Turn the upper housing upside down, the weight of the float resting on the needle should seal the flow. Suck on the inlet fitting, put your tongue over the hole. If it won't hold vacuum, it is not sealing.

I just went through something about like this. tractor would start and idle great. wouldn't run very well above idle. cleaned carb, new plugs and points didn't help. what I found was that the weights for distributer advance were sticking. unscrewed the points plate and cleaned them. easy fix. not saying this is your problem, but it fixed my tractor. good luck

Thank you for the info. I replaced plugs, wires, rotor, rotor cap etc. Starts and runs a little better but still sputtering with the black smoke. Carb coming off now for a cleaning...

Sir,
I did everything you recommended and it still runs more or less the same. I did however re-check for spark by removing a plug. Very weak spark. We ve had this tractor for quite. While now and it s had this problem on and off since we ve Owned it. It s at a hunting camp so every backyard mechanic has had their fingers in the mix trying to fix it. It was converted to 12v a long time ago and I have a feeling something isn t wired quite correctly. This weekend I am going to rewire the whole thing. Is there a 12v wiring diagram I can use that s out there somewhere? We have no lights on the tractor so I won t need to wire those up. It also only has a DC volt gauge and no AMPS gauge, and gas gauge doesn t work. Should I replace dc volt gauge with amps gauge, and possibly also put in a new key switch? Thank you so much for all your help and advice. 1960-ish Ford 861 Powermaster.