Engine shuts down

[Dchunter]

My 140 has been acting up lately. Early spring I took it out and it would run a bit and shut down. I would check the primer bulb and it would not be flat, but it was empty. I would re-prime the engine and it would start and run, but eventually shut down again. I filled the 50 gal tank back up and it ran good until it got to 3/4 of a tank. Now it is doing it again. I can squeeze the primer bulb to keep the engine running, but I am trying to figure out what is wrong. I am going to check and see if it has a anti-siphon valve to make sure it is not the problem, and check to see if there is something internally wrong with the primer bulb. It does not collapse. I am also buying a small plastic tank to make sure it is not the fuel pump although when primed it seems to pull the gas out of the line. It just does not pick up gas on its own. Anyone have any other suggestions on
what could be causing this problem?