Thread: Speedo not working properly

Hi all,
I have a 150 yamaha 4 stroke motor on my boat and the speedo is only registering 4 knots max, I know it works on water pressure from a little hole in the front of the gearbox so am assuming that its blocked with debris like sand...sooo, how can I clear it?
Cheers

Take a small drill twist bit and twirl it in the pickup hole. If you fear it may disappear into the works, put tape on your end to prevent same. Usually you’ll hit casting before whole length of drill inserted.
After twist bit twirls freely, look above water intake and you’ll see a clear plastic hose. It should be joined with and internal connector. Simply pop the connector and blow air back down the tube to where water intake is, thus clearing debris.

spray some " 30 seconds, walk away" thru it, you probably have some calcification or crud stuck in it.