Fuel pump not sending fuel Volvo Penta 4.3

[travelingts]

Going Crazy......boat starts when cold. Runs beautifully. Troll for couple of hours with electric motor. Boat won't start. Or will start, then runs out of fuel. Problem is, doesn't do it all the time. half the time it starts right up, no problem. Replaced fuel pump, relay and new carb. When not starting, no fuel being pumped to carb. Lots of oil pressure. Was told there was an oil pressure switch that cuts fuel to motor if no oil pressure is detected. I can only find one oil pressure sending unit on motor. It is located near oil filter. Does anyone know where the other kill switch would be located? After 5-10 minutes of cranking, motor finally gets fuel and runs great. Been fighting this for almost a year and l'm losing it. ANY help would be appreciated.
Rick