Some good advice here, any of the above could cause a lack of fuel problem.
With the gas turned on at the tank, remove the pipe plug at the bottome of the fuel bowl on the carb, have a catch can ready, a lot of fuel will come out at first until it has drained the bowl on the carb, give it a minute or two, and then see how much fuel is coming out of it, if the fuel line, sediment bowl , float & needle and tank are in good working order fuel should continue to come out faster than the plug hole can keep up, shut the fuel off at the sediment bowl on the tank, & fuel should continue to run out of the carb bowl for 10 seconds or so. If not, you have to isolate the flow problem, start at the tank, drain it, and check the tank for trash, rust or any obstruction where the sediment bowl screws in, check the sediment bowl while you have it off for any obstructions, re-install the sediment bowl, set a coffe can under it, fill the tank enough to cover the sediment bowl stand pipe and turn the fuel on, turn it back off, re-install the sediment glass bowl & replace the screen, leave the glass loose, turn the fuel on, & it should fill up quickly, turn it back off, install the fuel line, leave the carb end off, turn the gas on, fuel should flow freely at the carb end, coffe can should be about full by now, the only thing left is the needle & seat.
Remove the carb bowl to check the needle & seat on the float, you may have trash in the seat or possibly a needle with a rubber tip, check to see if your needle is completely metal with no rubber tip, the rubber ones are notorius for sticking. Check the pin that the float actually hinges on, make sure it operates freely, with hardly no side play, and no binding or sticking thorugh it's amount of travel.
Attach the fuel line to the carb. Now have your wife turn the gas on the sediment bowl, fuel should flow freely through the needle & seat, now that we are sure the gravity part of the system is functional, re-install the carb bowl with a new gasket.
Loosen the packing nut ( 7/16 wrench) one turn on the main jet needle valve, turn the spring & screw counter clockwise until it is in your hand, suirt a shot or two of carb cleaner into the jet hole, squirt the main jet needle & spring you have in your hand & wipe with a rag, DO NOT use any abasive to clean the tip, only carb cleaner & a rag. Have you wife turn the gas on again and in a minute or two gas will come out of the main jet hole have her turn it back off, re-install the needle & spring into the carb, turn it by hand until it bottoms out, DO NOT overtighten just until it quits turning clockwise, back it out 3 and 1/2 turns, tighten your packing nut snug not tight. When plowing for instance that same needle should be out 4 to 5 turns, this controls the fuel mixture under load.
Another one that I learned the hard way, is remove the fuel line where it attaches to the carb, and remove the fine screen, replace it with a new one, it hardly takes anything to slow the flow of fuel through it. To test to see if that is one of the problem you can remove it & then test run your engine to see if that's the problem.