I really need help with my Malibu Sportster

Hi I have 1999 Malibu Sportster with a 350 chevy Indmar motor I tried to start it yesturday and it would not start.There was no fuel getting to the carbaurator, so I checked fuel pump and traced it back to the oil pressure sensor.I Replaced oil pressure sensor, now it will start and the fuel pump will run but after about 45 seconds the engine dies. After a couple seconds I can fire the boat up again but same thing happens. I haved checked for corrosion and everything is clean as far as wiring goes. Your help would be Very Appreciated.

fuel pump still running after startup? Hook a test light to it to see. Could be a bad switch, even right out of the box.

Thank you very much for your response. I bought a new upgraded switch now. I haven't tested to see if the pump stays on after startup, I just tested that it came on when the key is on, and it does. Its gotta be just a bad switch. I will update when I install that new switch.

Cheers