Yamaha 250 stalls after running fine at 4500 RPM for about a minute. The bulb seems soft, when Its running it sounds fine, same as always. I think It's not getting fuel somehow. I replaced inline water seperator (do that frequently anyway) also repleced screen filter on the engine but that seemed fine, still stalls. Ventilation is not blocked. Where should I be looking? Could It be the bulb itself? any other suggestions would be much appreciated.......AL