Merc 15 EFI Pro Kicker electrical interference

[man164]

I have a new Mercury 9.9 kicker - I don’t notice interference, but I do have a noticeable whine at certain RPM’s. I might have to try the propeller you mentioned to see if it helps with the whine.

[bloodman]

Originally Posted by man164

I have a new Mercury 9.9 kicker - I don’t notice interference, but I do have a noticeable whine at certain RPM’s. I might have to try the propeller you mentioned to see if it helps with the whine.

The prop will not resolve the whine. That sound is inherent to the alternator/stator on the engine.

[Rick!]

What kinda boat is this 15 hp EFI kicker on to understand the cavitation thing? I've never had cavitation with my 15hp EFI kicker so I'm curious and it may help somebody else if they have the same rig.

[bloodman]

Originally Posted by Rick!

What kinda boat is this 15 hp EFI kicker on to understand the cavitation thing? I've never had cavitation with my 15hp EFI kicker so I'm curious and it may help somebody else if they have the same rig.

Mine is on a Ranger 621 but other have had similar issues. It is caused during high throttle trolling.
I suspect the Merc large hub 4 blade prop allows some of the exhaust to push forward over the gear case and back on the blades causing them to cavitate. This is only under heavy load.