Dave, I am not a mechanic, but I do have an older vehicle that has a Carburetor on it and I have been using MMO in my fuel and the carburetor is running great.
My thoughts are that MMO lubes everything in your fuel system.
I am also using MMO in the gas on my lawn mowers and 2 cycle equipment and they all start up on the 1st pull and they seem to be running better.
I used my Dad's Powerwasher a week ago that I had never put MMO in the fuel, it took about 3 pulls to get the thing started.
If you have sometime, visit the MMO Forum, its under " Ask The Mechanics", I believe someone asked a question about Ethanol in the gas, if I see a response then I will post it in this thread.
I have a friend who uses MMO and he has a 20 year old Ford Van that still has the original:
1) Fuel Pump
2) Fuel Injectors
This gentleman has about 200,000 miles on his Ford Van.