1981 242 non-turbo. I think the humming noise I hear when the engine is running (and the fan motor is disconnected) is the fuel pump. Listening with a stethoscope seems to pinpoint the sound to the main fuel pump in front of the tank. The Bentley says that if noise is the only symtom, the transfer pump should be checked first. The humming noise is loudest through the stethoscope the closer I get to the main pump. It's not as loud at or near the tank. Testing on the tank-to-pump fuel line the noise gets louder the closer I get to the main pump, then tapers off again as I get farther and farther in front of the pump toward the engine. Is this enough to diagnose the problem as the main fuel pump rather than the transfer pump in the tank. They're pretty expensive so I want to be sure. How long do they typically hum before going out completely? Any danger or added expense in waiting a while to repair? Any information or tips about this would be really appreciated.
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Thanks to everyone for the help, Doug C. 81 242 Brick Off Blocks, stock; 86 240, 129K, once in Rolling, now smashed quarter panel thanks to driver of an F150. Daughter safe in her Volvo.