What's crazy is that it's a 1976 carbureted 454 and while the gas is not fresh it will run but roughly, another vehicle sitting for 2yrs less time will run with my remote tank but not on it's spoiled gas. I'm thinking it had ethanol also, my 1950 Ferguson tractor would not run on it's gas either and it ran 3yrs ago. I have drained the tank and have the oil bath air cleaner soaking in solvent and hope to start it on fresh fuel that I'll test first.
I have a hell of a mess here with too many vehicles to maintain, while my Dad was sick not much got maintained except the Honda I bought to get him and my kids to the doctors, my Suburban still runs but the transmission is going out. I have a good one to go in it now and my Son will probably take it over so he can park his El Camino and fix it up. The one ton will eventually be my daily driver pickup and tow vehicle when needed but the calipers rusted stuck so I spent the other day beating the brakes loose, it will need new calipers and possibly a proportioning valve and lines if the empty master cylinder is any indication because if the fluid was not there to protect the lines they likely rusted shut. Something is leaking in the front brake system. So between bad fuel and brakes I'm busy as hell trying to get these vehicles going again. The one ton makes me money when it's running and I have time to buy and sell cars and equipment.
My buddy said he'd just junk it all and start over but I'm cheap and refuse to let simple to fix stuff keep me from moving forward, that and all this stuff is old like I prefer and it's all paid for. I have had chevy HD trucks with Duramax and Allisons and 454s with standards but they are plagued with problems that I cannot fix easily or cheaply but I never let em sit that long.
Never ending spending is where I'm at right now but I hope to slow that down some eventually, I get a little done every day so I'm heading in the right direction I hope.
My guess is the one ton truck has a sealed system with fuel injection, the rest are vented tanks & carbs. Gas will keep for a long long time in a sealed tank like on your truck, or a sealed gas can. In a vented carb like on small engines and tractors, not so much. 10% Ethanol or 100% Gasoline it all evaporates and leaves behind varnish/sludge. Best to at least run the carburetors dry if it's going to sit for more than a month or so.