Corroded fuel pick up pipe...
 

I had fuel problems, and inspected everything from tank to carbs. Found a crack/corroded pipe in the fuel pickup tube inside the tank, where it threads to the brass elbow on the tank round access plate/cap. I used a clear hose to troubleshoot the system and air was getting picked up from the gas-full tank.
Juan

Can you even purchase them pickup tubes or do you have to make them?
Years ago the same thing would happen to water heaters, the parts were'nt available so you had to make your own. Now they are bunched up on the shelf.

yes you can purchase the pick ups. they usualy sell in a predetermined length. you just have to get the one that is longer and snip it at angle untill to get the desired length.