1986 Questions for all other cars Gauge is showing no oil pr

Engine Mechanical problem
1986 Questions for all other cars 6 cyl Four Wheel Drive Automatic

My husband just called and his 86 Ford Bronco that he was driving to go deer hunting had started running bad. He said his oil pressure gauge was showning no oil pressure, he pulled over checked there was plenty of oil, the motor was not hot. He said when he took off he heard some noise in the engine, he took it slow and easy for the next 15 miles or so and parked it at a friends. How does one know for sure it is the oil pump. Or do we just change it and hope for the best?