If you have a fuel filter replace it! Dying upon "dumping can mean the little fuel enrichment pump inside the carb is malfunctioning.. However dying after 15 minutes may be other than fuel! It could be a coil or a dist pickup or a spark box (if any).
Does it jump around when dying or simply quit? If it just quits I'd be looking at the spark system.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

professional bovine relocation specialist