I have a Yamaha Sterndrive V6 4.3 on my old 1993 Century motorboat. Started it up and ran it for about ten minutes and it stalled out and won't restart. Yes there is gas in it. After messing around with I found that there is no gas getting up to the carburator. I'm thinking it may be the fuel pump. Any thoughts.... Also I'm told that this particular fuel pump is no longer being made. Can I substitute with another pump?. Thanks for your input