Sand in carburetor?

[Hattjason]

I have a 74 f250 that starts fine but won't stay running unless your foot is on the gas.
Lost a gas cap awhile back and I ordered a new one. While driving it without the cap It started running rough and dying. I took the fuel filter off and found the gas in the bottom of the filter cup was discolored brown and there was sand in the bottom. Replaced the filter and cleaned the cup. Also took apart and cleaned the glass inline filter. I left the line to the carburetor of and turned the key to check flow and got plenty. Truck started right up and runs smooth but still dies as soon as you let off the gas. Could the sand have made it into the carburetor and clogged things up there?
Also had a couple other questions. In one of the pics below can someone tell me what the arm is that I'm pointing to? I just noticed it wasn't connected and seems to be missing a retainer ring.
The other pic is what looks to be a ground wire coming off the distributor that doesn't look like it's ever been connected. Need to be?

 

[Hattjason]

Sorry. I couldn't find a way to add the pics on the original post

 

[Hattjason]

 

[Hattjason]

 

[Fellro]

That goes to your transmission, helps with shift points. Likely the transmission shifts the same no matter how hard you stomp on it. It has a clip that fits in the groove on that poin beside it to keep it from falling off.

Regarding the sand, it isn't supposed to, but if fine enough, anything is possible. Wire is the tach hookup, the distributor is a GM HEI style aftermarket replacement.

 

[Hattjason]

That goes to your transmission, helps with shift points. Likely the transmission shifts the same no matter how hard you stomp on it. It has a clip that fits in the groove on that poin beside it to keep it from falling off.

Regarding the sand, it isn't supposed to, but if fine enough, anything is possible. Wire is the tach hookup, the distributor is a GM HEI style aftermarket replacement.

Thank you for your reply and info. If not clogged with sand, any idea on what would keep it from running if the gas isn't pressed?
Carb air/gas mixture?

 

[Fellro]

Vacuum leaks will also cause similar issues. I have even seen egr valves stick open, and one pcv valve that had come apart. (plastic version)

 

[CowboyBilly9Mile]

I can't help but wonder if what you are calling sand is actually rust from the inside of the (steel) fuel tank...