Buzzing coming from fuel tank area

[Jgsj96]

I have a 1984 Evinrude 90hp. On the boat I have an accessory switch that the previous owner wired. When I turn it on I hear a buzzing that sounds like it’s coming from the fuel sending unit on the fuel tank. I have no idea what this switch does. Any ideas?

 

[Joe Reeves]

A buzzing noise from the fuel tank area when you throw a switch on? It may simply be a bilge pump running... BUT... I strongly suggest that, unless you've found what that noise is, that you refrain from engaging that buzzing and contact the previous owner to obtain exactly what that switch does.

 

[Faztbullet]

Could be a electric primer or fuel pump.