I'm having the same problem with a 2014 LM500, with 479CC Vanguard engine. I haven't changed the fuel pump yet, the Carb, was repaired a few months ago and was running just fine. It is doing the same thing now as before, I had a guy do some maintenance on it. I think I'll take the advice above and check the fuel lines also, it will only run for a few seconds and then shuts off.