CONSTANT SCREACH

[julesandmel]

Here's a stumper.
Mercury 60hp Bigfoot hasn't started in three years. Turn the key and immediate and constant shrill sound is heard. Oil tank is full. Engine is cold. Disconnect oil level sensor wires the alarm stops. Test the sender per manual (no continuity between wires) sender good. Soon as sender inserted into tank alarm sounds again. Changed to new sender, same same.
Can't be overheat sensor as that's a different circuit.
Thoughts?
Jules

 

[Fun Times]

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[julesandmel]

Thank you, Fun Times,
My boat, (24ft Party Barge with 2002 60 Bigfoot) has never emitted a beep at startup though once it did warn me of low oil level which I rectified immediately. I have verified that the oil pump is delivering oil and that the engine is not overheating as the cooling stream warms but does not scald. Thank you for the excellent info you have sent me. I will check all points offered.
Jules

 

[Dave1027]

Hook your ohm meter across the oil level sensors wires. Does the reading change when you insert the sensor into the tank?

 

[julesandmel]

Hook your ohm meter across the oil level sensors wires. Does the reading change when you insert the sensor into the tank?

Thank you Dave. Will do. Have to wait till weekend though. I suspect I'll get a continuity reading.
The service manual states that the oil tank is equipped with a magnetic float that completes the circuit when low oil. Wonder if that float no longer does so or is somehow stuck. I never did look inside the tank!